Aesthetic 3D Lighting: History, Theory, and Application
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Transcript of Aesthetic 3D Lighting: History, Theory, and Application
Aesthetic 3D Lighting: History, Theory, and Application
Aesthetic 3D Lighting: History, Theory, and Application delves into the history, the theory, and the practical and aesthetic application of lighting in the fine arts and 3D animation.
In this book, animation industry veteran and lighting expert Lee Lanier examines the importance of lighting and its ability to communicate information to the viewer. Lee examines the history of lighting as applied to the fine arts, film, photography, and 3D animation. He discusses the use of light color, light location and direction, and light shadow types to recreate specific locations and to generate moods. He includes guides for successful lighting in 3D animation. Software agnostic examples lead you through useful 3D lighting set-ups. Chap-ter-long case studies step you through more complex 3D lighting projects in Autodesk Maya. An accompany-ing eResource (www.routledge.com/9781138737570) features 3D model files, project files, and texture bitmaps, allowing you to practice the discussed techniques in Autodesk Maya and many other 3D programs.
The lighting techniques covered in this book include:
• History of lighting as used in the fine arts• The scientific mechanisms of light• Light types and light application in 3D programs• Light qualities including shadows variations• Basic and advanced 3D lighting approaches• 1-, 2-, 3-point, naturalistic, stylistic, and character lighting techniques• Replication of real-world lighting scenarios and locations• Overview of advanced 3D lighting and rendering systems
Lee Lanier has worked as a professional computer animator and VFX (visual effects) artist since 1994. He has more than 70 features, shorts, music videos, trailers, and commercials to his credit. Lee has written a doz-en high-end software books that have sold more than 35,000 copies, has authored VFX training videos for LinkedIn and lynda.com, has taught VFX compositing at the Gnomon School of Visual Effects in Hollywood, and is a member of the Visual Effects Society. A strong supporter of the arts, Lee co-founded the Dam Short Film Festival and is an avid painter and illustrator. You can see his work at beezlebugbit.com and diabolica-art.com.
Feedback and questions are always welcome. You can contact Lee at [email protected] or find him on popular social media networks.
Image copyright enki / 123RF Stock Photo. Photo.
Aesthetic 3D Lighting
Lee Lanier
History, Theory, and Application
RoutledgeTaylor & Francis Group
NEW YORK AND LONDON
RO
UTLE
DG
E
First published 2018by Routledge711 Third Avenue, New York, NY 10017
and by Routledge2 Park Square, Milton Park, Abingdon, Oxon OX14 4RN
Routledge is an imprint of the Taylor & Francis Group, an informa business
© 2018 Lee Lanier
The right of Lee Lanier to be identified as author of this work has been asserted by him in accordance with sections 77 and 78 of the Copyright, Designs and Patents Act 1988.
All rights reserved. No part of this book may be reprinted or reproduced or utilised in any form or by any elec-tronic, mechanical, or other means, now known or hereafter invented, including photocopying and recording, or in any information storage or retrieval system, without permission in writing from the publishers.
Trademark notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe.
Library of Congress Cataloging in Publication DataNames: Lanier, Lee, 1966- author.Title: Aesthetic 3D lighting : history, theory, and application / Lee Lanier.Description: New York : Routledge, Taylor & Francis Group, 2018. | Includes index.Identifiers: LCCN 2017057458 | ISBN 9781138737563 (hardback) | ISBN 9781138737570 (pbk.) | ISBN 9781315185279 (e-book)Subjects: LCSH: Cinematography--Lighting. | Animation. | Lighting, Architectural and decorative. | Light in art. | Three-dimensional imaging.Classification: LCC TR891 .L37 2018 | DDC 777/.52--dc23LC record available at https://lccn.loc.gov/2017057458
Publisher’s note: This book has been prepared from camera-ready copy prepared by the author.
Typeset in Myriad Proby BeezleBug Bit, LLC
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Contents
Introduction ----------------------------------------------------------------------------- xi
Chapter 1: The Importance of Light and Lighting ---------------------------- 1 Light and Lighting ----------------------------------------------------------------------------------- 2 Information Communicated by Light---------------------------------------------------------- 2 Time of Day -------------------------------------------------------------------------------- 2 Light Sources and Location ------------------------------------------------------------- 3 Mood ----------------------------------------------------------------------------------------- 4 Sidebar: Point-of-Views ------------------------------------------------------------------- 4 Sidebar: Light Shadowing ---------------------------------------------------------------- 5 Scientific Underpinnings of Light --------------------------------------------------------------- 6 Wavelength, Color, and Temperature ------------------------------------------------ 6 Reflection, Transmission, and Absorption ------------------------------------------- 7 Goals of Lighting ------------------------------------------------------------------------------------ 9 Story Communication ------------------------------------------------------------------ 9 Visual Clarity -------------------------------------------------------------------------------10 Replication of Real World Locations ------------------------------------------------ 11 Aesthetic Stylization -------------------------------------------------------------------- 11
Chapter 2: The History of Lighting in the Arts ----------------------------- 15 Review of Light Categories ---------------------------------------------------------------------- 16 Review of Point Lighting ------------------------------------------------------------------------- 16 0-Point Lighting -------------------------------------------------------------------------------------16 1-Point Lighting ------------------------------------------------------------------------------------ 19 2-Point Lighting ------------------------------------------------------------------------------------ 22 2-Point Lighting in Portraiture ------------------------------------------------------------------ 23 Rembrandt Lighting -------------------------------------------------------------------- 23 Loop Lighting ----------------------------------------------------------------------------- 25 Split Lighting ------------------------------------------------------------------------------ 25 Butterfly Lighting ------------------------------------------------------------------------ 26 Broad and Short Lighting -------------------------------------------------------------- 27 High- and Low-key Lighting ----------------------------------------------------------- 27
Contents
Detail from Portrait of an Old Woman, 1720-1745, by Balthasar Denner. Public
domain photos provided by The Yorck Project: 10.000 Meisterwerke der Malerei.
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Sidebar: Hard and Soft Lighting --------------------------------------------------------- 29 3-Point Lighting ------------------------------------------------------------------------------------ 31 3-Point Lighting with a Background Light --------------------------------------------------- 33 Other Limited Light Variations ------------------------------------------------------------------ 34 Naturalistic Lighting ------------------------------------------------------------------------------- 36 Stylistic Lighting ------------------------------------------------------------------------------------ 39 Sidebar: A Note on Video Games and Stop Motion Animation ---------------------------- 39 Chapter 3: Lighting in 3D ------------------------------------------------------------ 41 3D Lighting Pipelines and Workflow ----------------------------------------------------------- 42 Collecting Light Information -------------------------------------------------------- 42 Lighting Determination Examples -------------------------------------------------- 44 3D Lighting Steps ----------------------------------------------------------------------- 46 Testing 3D Lighting ---------------------------------------------------------------------- 48 Sidebar: Working with Color Calibration --------------------------------------------- 49 Working with 3D Lights --------------------------------------------------------------------------- 50 Common 3D Light Types -------------------------------------------------------------- 50 Spot Light ----------------------------------------------------------------------- 50 Point Light ---------------------------------------------------------------------- 51 Directional Light -------------------------------------------------------------- 52 Ambient Light ----------------------------------------------------------------- 52 Area Light ----------------------------------------------------------------------- 52 Sidebar: Using Light Decay ------------------------------------------------------------- 53 Common 3D Light Properties -------------------------------------------------------- 54 Shadow Variations Among Lights --------------------------------------------------- 56 Shadow Approaches -------------------------------------------------------------------- 58 Specialized 3D Light Types ------------------------------------------------------------ 59 Mesh ------------------------------------------------------------------------------ 59 Cylindrical ----------------------------------------------------------------------- 60 Environment ------------------------------------------------------------------- 60 Photometric -------------------------------------------------------------------- 61 Volume --------------------------------------------------------------------------- 61 Renderer Variations ----------------------------------------------------------- 61 3D Light Interaction with Shaders -------------------------------------------------- 62 Common Shader Properties -----------------------------------------------------------65 Sidebar: Texture Overview -------------------------------------------------------------- 69
Chapter 4: Emulating Specific Light Sources ------------------------------------ 71 Emulating Natural Light Sources ------------------------------------------------------------------ 72 Sidebar: Source Models and Textures --------------------------------------------------- 72 Mid-day Sun ---------------------------------------------------------------------------------- 72 Sidebar: PBR Options --------------------------------------------------------------------- 74
Contents
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Sunset -----------=----------------------------------------------------------------------------- 76 Candle Flame -------------------------------------------------------------------------------- 76 Diffuse Window Light ------------------------------------------------------------------- 78 Emulating Artificial Light Sources ----------------------------------------------------------------- 81 Table Lamp ----------------------------------------------------------------------------------- 81 Sidebar: Selective Shadow Casting ----------------------------------------------------- 84 Neon Sign ------------------------------------------------------------------------------------- 84 Christmas Lights ---------------------------------------------------------------------------- 86 Lighting a Character with Different Light Sources ------------------------------------------- 88 Sidebar: Light and Shadow Linking -------------------------------------------------------------- 93
Chapter 5: Working with PBR Systems ----------------------------------------- 95 Choosing PBR --------------------------------------------------------------------------------------- 96 Review of Common Rendering Systems ----------------------------------------------------- 96 Scanline ------------------------------------------------------------------------------------ 96 Ray Tracing -------------------------------------------------------------------------------- 97 Overview of PBR Systems ------------------------------------------------------------------------ 98 Review of Common PBR Systems ------------------------------------------------------------ 100 GI ------------------------------------------------------------------------------------------- 100 Photon Mapping ------------------------------------------------------------ 100 Final Gather ------------------------------------------------------------------ 102 Radiosity ----------------------------------------------------------------------- 102 Point Cloud ------------------------------------------------------------------- 103 Irradiance Cache ------------------------------------------------------------- 103 Path Tracing / Monte Carlo Ray Tracing ------------------------------- 103 IBL ------------------------------------------------------------------------------------------ 106 Sky Systems ------------------------------------------------------------------------------ 107 Sidebar: Overview of Advanced 3D Renderers ------------------------------------------------- 108 Sidebar: Unbiased vs. Biased Rendering ------------------------------------------------------- 109 An Introduction to Render Passes / AOVs -------------------------------------------------- 109 Sidebar: Lighting Render Passes ---------------------------------------------------------------- 111
Chapter 6: Reproducing Locations and Lighting Characters ------------- 113 Lighting Locations and Characters ----------------------------------------------------------- 116 Reproducing Lighting at Specific Locations ----------------------------------------------- 116 Location #1: Elevator Landing ------------------------------------------------------ 114 Location #2: Bus Interior ------------------------------------------------------------- 120 Location #3: Outer Space ------------------------------------------------------------ 122 Designing Character Lighting ----------------------------------------------------------------- 125 Sidebar: Character Lighting Pitfalls ------------------------------------------------------------ 129 Sidebar: Measuring Light in Stops -------------------------------------------------------------- 131
Contents
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Chapter 7 : Designing Stylistic Lighting -------------------------------------- 133 Stylistic Planning ------------------------------------------------------------------------------------- 134 Generating a Mood ----------------------------------------------------------------------- 134 Creating a Tribute to Other Art Forms ----------------------------------------------- 134 Creating a Visually Unconventional Look ------------------------------------------- 138 Establishing a Parallel World or Timeline ------------------------------------------- 140 Stylized 3D Examples ------------------------------------------------------------------------------- 136 Sidebar: Motion Blur and Other Post-Process Effects --------------------------------------- 145 Case Study 1: Copying a Renaissance Still Life --------------------------- 147 Using Autodesk Maya with the V-Ray Renderer ------------------------------------------ 148 Sidebar: Reloading Missing Texture Bitmaps ------------------------------------------------- 148 Sidebar: Gamma-Corrected Views -------------------------------------------------------------- 150 Switching to the Arnold Renderer ----------------------------------------------------------- 156 Creating a Window Reflection ----------------------------------------------------------------- 159 Adjusting the Render Quality ----------------------------------------------------------------- 162 Sidebar: Determining Values -------------------------------------------------------------------- 164
Case Study 2: Lighting a Complex Night Interior --------------------------- 167 Using Autodesk Maya with the Maya Software Renderer -------------------------- 168 Switching to the V-Ray Renderer and Adding Fog ---------------------------------------- 177 Case Study 3: Lighting an Animated Animal Character ------------------ 185 Using Autodesk Maya with the Maya Software Renderer ----------------------------- 186 Switching to the Arnold Renderer and Adding a Sky Shader ------------------------- 193 Sidebar: Creating Skies in 3D --------------------------------------------------------------------- 197
Epilogue: The Future of 3D Lighting ------------------------------------------- 199
Appendix: Visual Lighting Glossary -------------------------------------------- 203 0-Point Lighting --------------------------------------------------------------------------------------------- 203 1-Point Lighting --------------------------------------------------------------------------------------------- 203 2-Point Lighting --------------------------------------------------------------------------------------------- 203 3-Point Lighting --------------------------------------------------------------------------------------------- 204 Ambient Light ----------------------------------------------------------------------------------------------- 204 Area Light ----------------------------------------------------------------------------------------------------- 204 Back Light ----------------------------------------------------------------------------------------------------- 204 Background Light ------------------------------------------------------------------------------------------- 204 Bounced Light ----------------------------------------------------------------------------------------------- 204 Color Bleed ---------------------------------------------------------------------------------------------------- 205 Color Temperature ------------------------------------------------------------------------------------------ 205 Butterfly Lighting ------------------------------------------------------------------------------------------- 205 Depth Map Shadow --------------------------------------------------------------------------------------- 205 Diffuse --------------------------------------------------------------------------------------------------------- 205 Directional Light ------------------------------------------------------------------------------------------ 206
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Environment Light ---------------------------------------------------------------------------------------- 206 Eye Light ----------------------------------------------------------------------------------------------------- 206 Fill Light ------------------------------------------------------------------------------------------------------ 206 Final Gather (GI) -------------------------------------------------------------------------------------------- 206 Fresnel Reflection ------------------------------------------------------------------------------------------- 207 Glamour Lighting ------------------------------------------------------------------------------------------- 207 Hair Light ------------------------------------------------------------------------------------------------------ 207 Hard Lighting ------------------------------------------------------------------------------------------------ 207 High-key ------------------------------------------------------------------------------------------------------- 207 IBL (Image-based Lighting) ------------------------------------------------------------------------------ 208 Key Light ------------------------------------------------------------------------------------------------------ 208 Kicker (Light) ------------------------------------------------------------------------------------------------- 208 Lighting Ratio ------------------------------------------------------------------------------------------------ 208 Light Ray ------------------------------------------------------------------------------------------------------ 208 Loop Lighting ------------------------------------------------------------------------------------------------ 208 Low-key ------------------------------------------------------------------------------------------------------- 209 Mesh Light --------------------------------------------------------------------------------------------------- 209 Naturalistic Lighting --------------------------------------------------------------------------------------- 209 Path Tracing (GI) -------------------------------------------------------------------------------------------- 209 PBR (Physically-Based Rendering) ---------------------------------------------------------------------- 209 Photometric Light ------------------------------------------------------------------------------------------ 209 Photon -------------------------------------------------------------------------------------------------------- 209 Photon Mapping (GI) -------------------------------------------------------------------------------------- 209 Point Light ---------------------------------------------------------------------------------------------------- 210 Radiosity (GI) ------------------------------------------------------------------------------------------------ 210 Ray Tracing -------------------------------------------------------------------------------------------------- 210 Ray Trace Shadow ----------------------------------------------------------------------------------------- 210 Refraction ---------------------------------------------------------------------------------------------------- 210 Rembrandt Lighting -------------------------------------------------------------------------------------- 210 Renderer ------------------------------------------------------------------------------------------------------- 211 Rim Light ----------------------------------------------------------------------------------------------------- 211 Shader (Material) -------------------------------------------------------------------------------------------- 211 Secondary Diffuse Illumination ------------------------------------------------------------------------- 211 Silhouette Lighting ---------------------------------------------------------------------------------------- 211 Sky System --------------------------------------------------------------------------------------------------- 211 Soft Lighting ------------------------------------------------------------------------------------------------- 211 Specularity ---------------------------------------------------------------------------------------------------- 211 Split Lighting ------------------------------------------------------------------------------------------------ 213 Spot Light ---------------------------------------------------------------------------------------------------- 213 Stylistic Lighting ------------------------------------------------------------------------------------------ 213 Utility Light ------------------------------------------------------------------------------------------------- 213 Volume Light ---------------------------------------------------------------------------------------------- 214
Appendix: Common Question Index ------------------------------------------- 215
Index ------------------------------------------------------------------------------------ 219
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The world around you, as seen through your eyes, comes courtesy of light. The light may arrive from the sun, a flame, or an electric bulb. Hence, when building our own worlds within a 3D program, you must generate light with special tools. While the tools are fairly easy to master, it’s the aesthetic component of lighting that can be mysterious. In this context, an aesthetic is a set of principles that guide the lighting choices. Hence, when we discuss “aesthetic 3D lighting,” we are examining lighting principles developed in the fine arts and in the animation industry.
You, the Reader
Aesthetic 3D Lighting: History, Theory, and Application is aimed at any artist who would like to improve their 3D lighting skills. This book assumes that the reader has a basic mastery of a 3D program—any 3D program that supports lighting. This might include 3D animation programs such as Autodesk Maya, Autodesk 3ds Max, Autodesk Softimage, MAXON Cinema 4d, and Blender. This also applies to 3D programs that are designed for specialty tasks such as sculptural modeling, including Pixologic ZBrush and Autodesk Mudbox, or effects simulation, such as SideFX Houdini. This includes programs designed for industrial design and architectural visualization, such as Autodesk AutoCAD and Lumion. Video game engines, such as Unity, also qualify. In ad-dition, the 3D lighting techniques discussed here apply to 2D compositing programs that offer a 3D environ-ment, such as The Foundry Nuke, Blackmagic Fusion, and Adobe After Effects. It’s assumed that the reader can undertake the basic manipulation of objects, including lights and cameras, and is capable of test rendering in the program of choice.
Topics Covered
Aesthetic 3D Lighting: History, Theory, and Application is broken into seven chapters and three case studies. The topics include:
• History of lighting as used in the fine arts• The scientific mechanisms of light• Light types and light application in 3D programs• Light qualities including shadows variations• Basic and advanced 3D lighting approaches• 1-, 2-, 3-point, naturalistic, stylistic, and character lighting techniques• Replication of real-world lighting scenarios and locations• Overview of advanced 3D lighting and rendering systems
ContentsIntroduction
“Lights down on the main stage” by Edward Simpson licensed under Creative
Commons Attribution-ShareAlike 2.0 Generic (CC BY-SA 2.0).
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Agnostic Approach
The first seven chapters of Aesthetic 3D Lighting: History, Theory, and Application are software agnostic. That is, you can apply the lighting theory and technique within any 3D program that supports lighting. The three case studies at the end of the book include exercises specific to Autodesk Maya. Autodesk Maya is a high-end, pro-fessional 3D program used widely in the visual effects, feature animation, and commercial production indus-tries. If you don’t have access to Maya, you can use the case studies as a guide when using other 3D software.
SoftwareAesthetic 3D Lighting: History, Theory, and Application was written with Autodesk Maya 2017 and Maya 2018. Screen snapshots were captured on a 64-bit Windows 10 system. Educational versions of Autodesk Maya are available at www.autodesk.com.
Exercise Files and Updates
Exercise files and book updates are included at the following website:
www.routledge.com/9781138737570
The exercise files include 500 megabytes of FBX model files, Autodesk Maya 2017 and Maya 2018 project files, and texture bitmaps. The files are organized in the following directory structure:
Project-Files\Models\ 3D models, suitable for importing (.fbx)
Project-Files\Maya\ Maya project files (.ma and .fbx)
Project-Files\Textures\ Bitmap textures (.png and .jpg)
The Maya scene files are saved as student versions and are intended for educational purposes.
Using the Exercise Files
I recommend that you copy the project files, with their current directory structure, directly to your root direc-tory (C: on a Windows system or / on a Mac system).
The 3D models used in Chapter 4 and Chapter 6 are saved in a binary FBX format (version 2014/2015), which you can import into a wide range of 3D programs. The textures are saved as PNG and JPEG bitmaps. If you choose to import an FBX file, you may need to map, link, or reload the texture bitmaps through corresponding shaders. If you are working with a 3D program that is unable to read the shader set-ups properly, you can still apply the lighting techniques with simple shaders that only provide a solid color. Alternatively, you can assign your own unique textures.
Autodesk Maya project files, saved in the ASCII .ma format, are included for the chapter-long case studies at the end of this book. You may need to reload the texture bitmaps for these scenes. Instructions for doing this are included with the first case study. In addition, copies of the scene files are included in binary FBX format (version 2014/2015) should you choose to import them into a different 3D program.
Introduction
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Licensing Information
The 3D models and texture bitmaps included with the exercise files for this book are licensed via Creative Commons. Author and licensing information is included in the model-license.xls and texture-li-cense.xls files in the Project-Files directory. For more information on Creative Commons, visit creativecommons.org. In addition, many of the photos and graphics used for the book’s figures were licensed. Licensing/copyright captions are included with the matching figures. Figures that feature screen snapshots from motion pictures, television shows, and video games are used strictly for educational purposes; the use of these snapshots does not infer any specific transfer of rights.
Naming Conventions
Aesthetic 3D Lighting: History, Theory, and Application uses common conventions when describing mouse oper-ation. For example, LMB-drag refers to pressing the left mouse button, dragging the mouse, and releasing the mouse button. Note that Autodesk Maya is dependent on a three-button mouse.
Program, Lighting, and Filmmaking Terminology
When discussing lighting theory, I’ve tried to follow common scientific conventions. When referring to techniques of 3D lighting, I’ve used terminology often used by 3D animators and support documents of 3D programs.
Visual Glossary and Definitions
A visual glossary defining useful lighting terms is included near the end of this book. The glossary includes terms used in the real-world and in the realm of 3D animation. Additional lighting terms are defined through-out this book—these are indicated with a bold typeface.
Future Thoughts
“The Future of 3D Lighting” is included near the end of this book. This short section contemplates develop-ments in lighting and ways to keep up with lighting trends and techniques.
Lighting Quotes
Sprinkled throughout this book are quotes by artists, writers, filmmakers, actors, and philosophers on the topic of light and lighting. These relate to the subject only loosely. Nevertheless, I hope they inspire contemplation and creativity as you proceed to light.
Introduction
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“I find great lighting and a squint of the eyes makes anyone look better.” —Cat Deeley
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Chapter 1: The Importanceof Light and Lighting
Light is a critical part of human experience. It permits us the sense of sight. It communicates information about our environment. It can alter one’s mood. Light, as a natural phenomena, is complex. Nevertheless, its basic properties can be mastered and applied to the arts.
This chapter includes the following critical information:
• Information communicated by light • Scientific underpinnings of light • Goals of lighting
Photo copyright Rungaroon Taweeapiradeemunkohg / 123RF Stock Photo.hoto.
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Light and Lighting
Light, as a general term, is a natural agent that stimulates sight and makes objects visible. Lighting is the pro-cess of placing and adjusting lights, whether those lights are real, as in stage and film lighting, or virtual, as in 3D lighting. Before we begin the lighting process, however, it’s important to examine the information commu-nicated by light and the natural phenomena that generates light and allows it to interact with the world. It’s also useful to have a specific goal when lighting, which we will discuss at the end of this chapter.
Information Communicated by LightInformation is gained through the presence (or absence) of light. As such, light is able to:
• Indicate the time of day • Reveal light sources • Infer the general location • Instigate a particular mood
Time of DayAs a human living on the planet Earth, we have learned that various lighting scenarios are linked to certain times of day. In the simplest way, we can differentiate between daytime and nighttime. If we examine addi-tional clues, we can identify a sunset, sunrise, or mid-day. Sunrise and sunset generally produce more saturat-ed colors that tend toward reds and yellows (Figure 1.1). Sun light from a sunset or sunrise arrives at a lower angle as the sun nears the horizon. (The only difference between a sunrise and sunset is the sun’s relative direction of travel—whereby it arrives or departs from view.) In contrast, sun light at mid-day arrives from a high angle. Depending on the season and the location, the mid-day sun approaches at a perpendicular angle to the ground. On a clear day, sunlight at mid-day appears more blue.
Figure 1.1 Several frames from a time-lapse video of a city reveal differences in sun light direction, sun light color, and shadow
length. Starting from the top-left and going clockwise, the frames transition from mid-day to afternoon to sunset to twilight.
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Time of day is not limited to natural light sources. If the sole source of light is an artificial source, such as a lamp, one can assume that it is night. Alternately, one can assume that the location is in a closed space that prevents sun light from entering. Examples include a cavern, a theater auditorium, or a room with shuttered windows.
Light Sources and LocationThrough life experiences, humans learn that various lighting qualities are associated with particular light sources. In addition, clues on the location can be taken from the light information. Table 1.1 includes a few common examples.
Table 1.1
Light Quality Light Source and Possible Locations
Strong, overhead light arriving from a single source creating a single distinct shadow (left side of Figure 1.2).
Sun, most likely outdoors.
Strong, overhead light arriving from multiple sources and creating overlapping shadows or a single soft shadow (right side of Figure 1.2).
Banks of artificial lights, such as overhead fluores-cent lights in an office or groups of flood lights in a stadium.
Flickering light with red, orange, and yellow color and soft undulating shadows.
Fire light. Based on the intensity of the light and its relative motion, you can extrapolate how the fire is used (e.g. bonfire, fireplace fire, torch, candle flame, match flame, and so on).
A “wall” of light arriving from one location and travel-ing in one direction.
Light from a television screen or monitor, sun light traveling indoors through a window, or light reflected off a large surface, such as a floor.
Figure 1.2 Left: Woman photographed outdoors with the sun as the light source. There is a single, distinct shadow. Secondary light is reflected off
the ground. Right: A woman is photographed in an office with banks of overhead lights creating soft shadows. In addition, a wall of sun light arrives
from windows at the left side of the frame. Reflected light also arrives from the floor and nearby walls.
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The Importance of Light and Lighting
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Note that moon light is another major source of naturally-occurring light. However, moon light is sun light reflected off the moon’s surface. Hence, moon light can be treated as a weaker source of sun light.
MoodMood is a temporary feeling. Moods are often triggered by particular lighting scenarios. For example, people generally associate happiness with bright sunlight. In an opposite way, people associate unhappiness, dreari-ness, or gloominess with the dim lighting of an overcast sky. The soft, warm illumination of fire light or candle light often enhances beauty or attractiveness and is thus associated with romance. Along the same lines, fashion photography often employs various forms of stylistic lighting to maximize beauty while minimizing the natural defects that all humans carry (such as wrinkles, scars, and so on). When I use the term stylistic, I am referring to light scenarios that generally do not occur in the real world without manipulation.
You can alter mood with artificial light sources. This is a common trick of cinematographers and videogra-phers. For example, to portray a moon lit scene in film, a blue light or blue color balance is sometimes used. To increase tension within a horror film, highly saturated and stylistic lights, such as those with red or green color, may be employed. These lights are sometimes placed at unusual locations so that the lights create exaggerat-ed highlights and shadows (Figure 1.3).
Points-of-view
When discussing lighting, it’s assumed that there is a point-of-view. That is, the lit scene is viewed from a particular point in space. The point-of-view affects how the light is seen. Two different points-of-view may cause the lighting to be perceived differently. When discussing lighting in the arts, the point-of-view is selected by the artist. With classic arts, such as drawing or painting, this view is recorded on paper or canvas. With a stage play, the view is the general view of the audience. With modern arts, such as photography, videography, and 3D animation, the view is the view through the camera lens.
Figure 1.3 Detail from a frame of the motion picture Frankenstein
(1931). The actor is lit from below, creating grotesque shadows
across the face.
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Light ShadowingA shadow is a dark area created when an object comes between a light source and a surface. In this scenario, light is blocked from the surface. Even though a shadow results from the lack of light, it also communicates important information. For example, a shadow indicates the direction of a light source. If a shadow extends a great length away from the object, then the light source arrives at a low angle (parallel to the surface receiving the shadow). Hence, sunset light creates “long” shadows. If the shadow tightly surrounds the object, the light source is above the object. Hence, noon-time sun creates “short” shadows (top of Figure 1.4).
The quality of the shadow can also give clues to the nature of the light source. For example, if the shadow edge is sharp and clearly defined, the light source is generating parallel rays of light. This form of light is most often created by the sun on a clear day. If the shadow is clearly defined near the shadowed object but becomes soft over distance, the light source is most likely close by and is man-made (bottom of Figure 1.4). An incandescent light bulb creates this effect.
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Figure 1.4 Top: Overhead light of the sun causes the shadow of a tree to be “short,” where the
trunk portion of shadow is barely visible. Bottom: An artificial light, placed close to the chess
pieces, creates a shadow that softens over distance and causes the shadows to fan out in a
non-parallel fashion.
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Scientific Underpinnings of LightFrom a scientific perspective, light is electromagnetic radiation that exists within a specific portion of the elec-tromagnetic spectrum. For the purpose of this book, we will limit our discussion of light to visible light, which is perceptible to the human eye. Although a scientific investigation of light may seem unnecessary, an under-standing of the fundamentals will help you make decisions when fine-tuning 3D lights and 3D light systems.
Light is often described as both a wave and as photons. A photon is an elementary particle that represents a quantum of electromagnetic radiation produced by an electromagnetic field. A light wave represents the fluctuating energy state of photons. When discussing light color, wavelength is generally invoked. This is described in more detail in the next section. However, when describing light and its interaction with material surfaces, the concept of photons is often employed. In fact, some 3D lighting and rendering systems use virtu-al photons to replicate light as it reflects off surfaces and transmits through surfaces.
Wavelength, Color, and TemperatureElectromagnetic radiation travels through the vacuum of space in a straight line at a fixed speed (3x108 meters/second). However, the fluctuating energy state of the associated photons can be described with a wave-like pattern with peaks and valleys. Different forms of radiation possesses different wavelengths. A wavelength is the distance of successive peaks of a wave. With electromagnetic radiation, wavelength is mea-sured in nanometers. A nanometer is one billionth of a meter and is written as nm. Different wavelengths are perceived as different colors by the human brain. For example, “long” wavelengths within the visible spectrum are perceived as magenta or red. “Short” wavelengths within the visible spectrum are perceived as blue or violet. Wavelengths within the visible spectrum fall between 400 and 700 nm (Figure 1.5).
700 nm 650 600 550 500 450 400 nm1,000 K 2,800 K 4,800 K 10,000 KFigure 1.5 A simplified chart showing the visible light spectrum. Wavelength is shown as nanometers with longer wavelengths on the left and shorter
wavelengths on the right. Temperatures, written in kelvin, increase from left to right. Thus, as temperature increases, wavelength decreases.
Chapter 1
“Give light, and the darkness will disappear of itself.” —Desederius Erasmus
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A light source, such as the sun or a light bulb, releases electromagnetic radiation as its material is heated. The sun undergoes nuclear fusion due to the extreme pressures at the sun’s core. A light bulb filament is heated when electricity is passed through the filament wire, which possesses high electrical resistance. Hence, heat (which is produced by the vibration of electrons attached to the atoms of the material) is converted to visible light. As such, there is a direct correlation between temperature and the color of visible light (Figure 1.5). For example, the temperature of an incandescent light bulb filament falls between 2800 and 3700 kelvin. A kelvin, written as K, is a unit of measure for temperature based on an absolute scale, where 0 kelvin is the point at which all atomic vibration has ceased (and no heat is generated). The kelvin scale employs an ideal black body radiator, which is a theoretical material that absorbs all incident electromagnetic radiation. As such, the term color temperature refers to a temperature of a black body in kelvin. This scale is used to correlate the visible color of lights. Lower K temperatures appear orange or yellow. Higher K temperatures appear blue. For exam-ple, the sun’s light, when affected by the Earth’s atmosphere, may range from 4800 K (direct sunlight) to 7000 K (cloudy sky) to 9500 K (clear blue sky). Sun light from a sunrise or sunset is closer to 3200 K. Hence, a sunrise or sunset often produces an orange light, much like an incandescent light bulb with a similar color temperature. Some light bulbs, whether they are incandescent, fluorescent, or LED, are labeled “daylight,” indicating their 5000 K to 6500 K color temperature that’s equivalent to sun light on a bright day.
Reflection, Transmission, and AbsorptionLight is described as having a continuous range of wavelengths. However, when light with a specific wave-length reaches a material surface, one of three things happens:
• The light is absorbed and the light energy is converted to heat (left side of Figure 1.6). • The light is absorbed and re-emitted. Hence, the light is reflected (center of Figure 1.6). • The light is absorbed and its energy is transmitted from atom to atom through the material. The light is
re-emitted at the opposite side of the material (right side of Figure 1.6). This occurs with transparent or semi-transparent materials such as glass or water.
If the frequency of the light matches the natural vibrational frequency of the atom’s electrons, the light is absorbed and the light energy is converted into vibrational motion, which in turn is perceived as heat. If the frequency of the light does not match the natural vibrational frequency of the atom’s electrons, the light is re-emitted through reflection or transmission. Frequency refers to the number of occurrences within a particular time frame. Hence, a light wavelength will have a particular number of peaks and valleys over a time frame. The oscillation of an electron’s vibration can also be defined as a wave.
The Importance of Light and Lighting
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Figure 1.6 Left to right: Light absorption, light reflection, and light transmission. Light with a specific wavelength that arrives from a
specific angle is represented as a light ray and is drawn as an arrow. The surface normal is drawn as a red-dotted line and is mathematical-
ly perpendicular to the surface.
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Materials do not contain color. Color is perceived because a material reflects or transmits specific wavelengths. For example, if a ball appears red, it’s because the material of the ball absorbs all the visible wavelengths except for red; the red wavelength thereby is emitted toward the viewer. By the same token, the reflected light may not maintain the original wavelength. Hence, blue sunlight may no longer appear blue when reflected off of a red surface. That said, light color tends to color bleed, whereby the color of one surface affects the color of a second surface. For example, the light reflected off a red backdrop may influence the color of white statues (Figure 1.7). In this case, the statues reflect a pinkish color toward the viewer. Hence, the red of the backdrop and the white of the statues is mixed. If a material appears pure white, it reflects most of the visible wavelengths. If a material appears pure black, it absorbs most of the visible wavelengths (hence, black surfac-es become hot more quickly under a light source).
Reflected light does not travel back on its original trajectory. Instead, the light follows an angle of reflection, which is equal to the angle of incidence but is mirrored on the opposite side of the surface normal. A surface normal is a line drawn perpendicular to the surface (see the center of Figure 1.6). When describing reflections and transmissions, light arriving at a specific angle is often referred to as a light ray. Light rays are also used to discuss ray tracing systems within 3D programs. The angle of incidence is the angle between the arriving light ray and the surface normal. As such, the incident light ray, the surface normal, and the reflection ray all lie in the same plane. Note that a reflection only occurs at a material interface (where two materials meet). For example, an interface may exist between the air and a hard surface, such as a piece of stone or metal. Light rays may be described as vectors. A vector mathematically defines direction and magnitude in 3D space.
When discussing 3D lighting, transmission is often referred to as refraction. This is due to the refraction of light. When light is transmitted through a surface, its speed is affected. The change in light speed causes the apparent light direction to change. Hence, objects refracted by a surface appear bent, warped, or broken. You can see this when you place a straw in a glass of water or if you peer through water drops (Figure 1.8). Due to their atomic makeups, different materials produce different degrees of refraction. The refractiveness is mea-sured as a refractive index, which is a mathematical formula that relates the speed of light in a vacuum to the speed of light through a particular material.
Figure 1.7 A set of white statues pick up a red “bleed” from their close proximity to red fabric.
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9
The Importance of Light and Lighting
Figure 1.8 Refractions visible within drops of
water.
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Goals of LightingWhen an artist lights, and thus creates lighting where lighting did not exist or was not satisfactory, he or she usually pursues one or more common goals. These goals are equally applicable to the modern arts, including photography, cinematography, videography, and 3D animation, as well as the classic arts, including those utilizing drawing, painting, and stage work. You can break these common goals into four main categories:
• Story communication • Visual clarity • Replication of real world locations • Aesthetic stylization
Story CommunicationThis category communicates common information humans have come to expect from light. As discussed earlier in this chapter, this includes the sources of light, general location, and the time of day. Longer time pe-riods can also be inferred with lighting. For example, bright, yellowish sunlight may be associated with warm summer, while dim, blue or gray light may be associated with a cold winter (Figure 1.9).
Figure 1.9 Left: Bright, yellowish light infers that it is a warm day. Right: Dim, gray light infers that it is a cold day.
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When the art is sequential and tells a story over time, such as a stage play, a motion picture, or an animation, changes in lighting can communicate changes in time. For example, if the lighting switches from what looks like afternoon to what looks like night, you can assume that the story has jumped to a point a few hours later.
Aside from time information, lighting may be used to communicate specific story details. For example, lighting can create a focal point that reveals important element of the plot or stresses an important component of the scene (Figure 1.10 and 1.11). A focal point is an area of the composition that naturally draws the viewer’s attention.
Chapter 1
Figure 1.11 Detail of The Third of May 1808, 1814, by Francisco de Goya. The central figure is given the most intense
light from a large lamp set on the ground. The white shirt, expressive face, and open stance further draws attention to
him and the plight of those in front of the firing squad.
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Figure 1.10 Detail of frame from the
motion picture Pulp Fiction (1994). An
unseen object within a suitcase throws
a golden spot of light, enhancing the
object’s desirability and inaccessibility.
The object is never revealed and remains
a MacGuffin, which is an object within
a story that serves merely as a trigger for
the plot.
© 1
994
Mira
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.
11
The Importance of Light and Lighting
Mood can also be established to communicate the mental state of the characters or to instigate a sense of negative foreboding or positive anticipation in the viewer. For example, in Figure 1.12, the extensive use of blue color within the clothing, background, and shadow areas make the subject appear depressed; the blue color, even if it was a stylistic invention, infers the presence of a blue light source. In Figure 1.13, red Christmas lights allude to the violence that will occur as part of a holiday horror plot—this serves as foreshadowing for the audience.
Visual ClarityVisual clarity is quality imparted to a scene, shot, or frame that makes the subject easily identifiable and understandable. The clarity is in reference to the visual quality of the scene, shot, or frame and not necessarily the story. For example, you can light actors or characters so they can be clearly seen against a background. A common example of this is the use of a rim light. A rim light creates a thin line of light on the character edge (Figure 1.14).
Figure 1.14 Detail of frame from the
motion picture Monsters University
(2013). A rim light on the monster’s
head and shoulders prevents him from
blending into the blue-lit background.
The grinning expression of the monster
prevents the blue light from being
construed as depressing or cold.
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Figure 1.13 Detail of frame from the motion picture Black Christmas
(1974). The calm appearance of the actress infers she is unaware of any
potential danger.
Figure 1.12 Detail of Self-Portrait with Grey Felt Hat,
1887, by Vincent van Gogh. The artist’s expression,
combined with the blue lighting, sets the mood.
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Chapter 1
The use of a focal point can also be employed for visual clarity. For example, in Figure 1.15, a potentially clut-tered scene is simplified by allowing parts of the set to remain unlit. As such, there are several focal points: the reflection of the man on the left, the intercom speaker on the right, and the two men in the background.
Along those lines, lighting can help establish a visual hierarchy, which is the arrangement of elements within a composition or setting that establishes importance. For example, if part of a frame is left dark and poorly lit, its importance to the viewer is diminished. When lighting performers on a stage, a bright spot light focused on one performer causes the audience to watch that performer. Other performers might be present—however, if they are lit with weaker lights, they will receive less attention.
Replication of Real World LocationsA common task within the arts is the replication of a real location. With a painting, there may be a desire to capture the lighting present at a real location during a specific time of day. With motion picture or television work, it may be necessary to alter the time of day or apparent time period at a real location or recreate a particular location on a sound stage (Figure 1.16). With 3D animation created for a visual effects job, it is often necessary to match the lighting that’s contained within pre-existing film or video footage; for example, a 3D car must take on the same lighting contained within a live-action shot in order to integrate the 3D car believably.
Aesthetic StylizationAs discussed in the Introduction, an aesthetic is a set of principles that guide the lighting choices. An aesthetic may be rooted in reality, where the lighting attempts to recreate common lighting scenarios in the real world. On the other hand, the lighting may attempt stylization, where there is no direct attempt to mimic the real world. Examples of stylistic lighting include abstract stage and concert lighting (Figure 1.17). We’ll take a closer look at stylization in Chapter 7.
Figure 1.15 Detail of frame from the motion picture Mulholland Drive (2001). Parts of the background curtain and foreground
floor remain unlit, allowing focal points to form around the reflection, speaker, and men.
© 2
001
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13
The Importance of Light and Lighting
Figure 1.17 A small stage is lit with no attempt to recreate a particular location in the real world.
Figure 1.16 Detail of frame from the motion picture North by Northwest (1959). A forest is recreated on a sound stage necessitating that the artificial
lighting recreate a sunlit outdoors.
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15
Chapter 2: The History of Lighting in the ArtsHumans have replicated light within the arts for millennia. As our comprehension of light has increased over time, so has the complexity with which we are able to recreate the lighting. You can trace aesthetic lighting theory and techniques through the traditional arts, such as a painting and stage, to modern forms that include motion pictures. You can use this knowledge to undertake lighting within the newest 3D programs.
This chapter includes the following critical information:
• Overview of 0-, 1-, 2-, 3-point, naturalistic, and stylized lighting • Lighting as used in the traditional arts • Lighting as used in modern and digital art forms
Detail from Yacht Approaching The Coast, c. 1840-1845, by J. M. W. Turner. Public
domain photos provided by The Yorck Project: 10.000 Meisterwerke der Malerei.
16
Review of Light CategoriesWhen examining lighting techniques, it’s often useful to assign categories to light sources. For the purpose of this book, I will use categories generally employed by photographers, cinematographers, videographers, and 3D animators. These include:
Key The brightest light source. This usually illuminates the main subject, such as a person or a character. A location generally requires a single key light, although several equally bright key lights may be needed. Key lights are sometimes referred to as main lights.
Fill A secondary light source. This may be a weaker light, such as a table lamp or television screen, or may represent reflected light. In this situation, reflected light is referred to as bounce light (the light “bounces” off one surface to the next). A location may require multi-ple fill lights to represent additional light sources and light bounce off multiple surfaces.
Utility This is a generic category that includes light sources that fill very specific functions that may be naturally derived or completely stylistic. These lights are often named after their function. For example, the lights include rim lights (with variations known as kickers), hair lights, back lights, eye lights, and background lights.
Review of Point LightingA common method of describing lighting is to refer to the number of required light sources. For example, 3-point lighting is a common lighting set-up with 3 lights: key, fill, and rim. Although 3-point lighting is useful for a limited number of lighting scenarios, you can apply the same naming convention on a wide variety of lighting situations. Hence, I will describe lighting as 0-, 1-, 2-, and 3-point lighting. I will reserve light scenar-ios that require more than four lights for the discussion of naturalistic lighting. I define naturalistic lighting as lighting that attempts to replicate the real-world as closely as possible, regardless of the number of light sources. In contrast, stylistic lighting makes little or no attempt to match the real world.
0-Point Lighting
I will start the lighting discussion with the art of ancient cultures with limited technological development. Although this category is fairly vague, you can identify one common trait of this art, which is 0-point lighting. 0-lighting occurs when art is given no lighting information. This is seen in rock paintings and shallow 2D carv-ings such as petroglyphs. When examining this art, there is no indication of time of day or location based on lighting information (Figure 2.1). By the same token, there are no shadows included in the art.
Chapter 1Chapter 2
161616161666
“We forget just how painfully dim the world was before electricity. A candle, a good candle, barely provides a hundredth of the illumination of a single 100 watt light bulb.” —Bill Bryson
17
In a similar fashion, hieroglyphics fail to carry light information. However, when the hieroglyphics and accom-panying characters were carved deeply into stone, they gained self-shadowing (Figure 2.2). Self-shadowing is a variation in surface brightness caused by the surface blocking the light from portions of itself. With such sculpture, self-shadowing changes when light around the sculpture is altered or when the sculpture is moved. Hence, the self-shadowing was not an intrinsic part of the art. In other words, the self-shadowing does not communicate story information, set a mood, or replicate a particular location. As such, we will limit our discus-sion on lighting to 2D artworks where the contained lighting has been made permanent by the artist.
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Figure 2.1 Top: Rock painting in Manda Guéli Cave in the Ennedi Mountains in Chad. The painting dates from the “Horse Period” (1250
B.C.-c. 950 A.D.). Bottom: Petroglyphs in the Nine Mile Canyon in Utah, created by the Fremont culture, which was active from 700-
1250 A.D.
The History of Lighting in the Arts
1717171717117
18
0-point lighting survives in contemporary art in the form of line illustrations (Figure 2.3). It can also be seen in animation that follows the tradition of hand drawing, cel painting, or 8-bit limited-graphics video games. With these forms, there is often no attempt to indicate lighting.
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Figure 2.3 Left: The ink drawing used for a single panel cartoon does not include lighting information. Right: A series of hand-drawn birds intended
for digital 2D animation does not include lighting information despite the drawing complexity and use of multiple colors.
Figure 2.2 Carved hieroglyphics and
characters from the Temple of Kom Ombo,
Egypt (c. 150 B.C.). Self-shadowing is
evident in the light of the sun, but does
not communicate story information.
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Chapter 1Chapter 2
19
1-Point Lighting1-point lighting is relatively rare, as it involves a single key light and no secondary lights (such as fill lights). This type of lighting is evident in early forms of portraiture, such as Egyptian funerary paintings, which were created from the 1st to 3rd centuries (Figure 2.4). This is also visible in religious icon paintings or stained glass artwork of Europe in the Middle Ages (Medieval Period), which ranged from the 5th to 15th centuries (Figure 2.5). It may be possible to identify a key light used for these artworks, but secondary lights are difficult to locate. Fill lights may be missing or may be arriving from all directions at once. As such, stylistic liberties were most likely taken by the artists.
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Figure 2.4 An Egyptian funerary portrait (“mummy portrait”), c. 100 A.D. Al-
though the portrait includes three-dimensional modeling and shading, it appears
to be lit by a single key light arriving from the painter’s point-of-view. The light
was most likely provided by the sun but may have also been a stylistic invention.
Figure 2.5 Left: Madonna and Child with Two Angels (Crevole Madonna), c. 1283 A.D., by Duccio. Despite the modeling and shading,
it’s difficult to identify multiple light sources. Right: Berner Standesscheibe stained glass panel, 1554 A.D., by Joseph Gösler. Once
again, there is modeling and shading without a strongly defined secondary light. Neither example includes cast shadows.
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The History of Lighting in the Arts
20
With technically accomplished paintings, you are most likely to see this scenario when there is a candle illu-minating a person in an otherwise dark location. As such, non-illuminated surfaces appear black (Figure 2.6). Such high-contrast lighting is a common trait of Renaissance oil paintings (created from the 14th to 17th cen-turies). Michelangelo Caravaggio (1571-1610) and Rembrandt van Rijn (1606-1669) were among the painters instrumental in developing the technique, which is known as chiaroscuro or light-dark.
0- and 1- point lighting appears in modern art, which spans the period from the 1860s to 1970s. As opposed to choosing a particular number of light sources, modern art often embraced the simplicity of ancient arts (Fig-ure 2.7). At the same time, modern artists often broke away from the artistic developments of prior centuries, forgoing technical developments such as perspective. This is particularly evident with early 20th century art that fits within the Cubist and Expressionist art movements. The intent of Cubism is to dissemble the visible world and reassemble it in a stylistic fashion. The intent of Expressionism is to present the world from a subjec-tive viewpoint in opposition to recording the world accurately with the goal of evoking a mood.
Chapter 1Chapter 2
Figure 2.6 Detail of Büßende Maria Magdalena (Magdalena Fabius), 1628-1645, by Georges de La Tour. A single light source, the candle behind the
skull, fails to light the back of the woman.Pu
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20202020200200“To light a candle is to cast a shadow.” —Ursula K. Le Guin
21
1-point lighting is sometimes employed in modern photography, cinematography, and videography and falls into the loose category of glamour lighting. Glamour lighting is used for television commercials, music videos, and fashion photography to impart an extra degree of beauty to the subject. A broad light source, such as a softbox light, light umbrella, or LED ring, is placed near or around the camera; the soft light prevents any significant shadows from forming on the subject’s face (Figure 2.8). In this case, soft light refers to diffuse, scattered, non-directional light.
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Figure 2.7 Left: Rotes und blaues Pferd, 1912, by Franz Marc. Right: Elvira mit weissem Kragen, 1918, by Amedeo Modigliani. Both paintings are con-
nected to the Expressionist movement. Although there is some degree of three-dimensional modeling, the light is stylistic and not intended to match
any particular real-world situation. The left painting may be considered 0-point lighting and shares similarities with ancient cave painting. The right
painting may be considered 1-point lighting, and shares similarities with portraits of the 1st millennium.Ph
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light near the camera. Hence, cast shadows are not visible and
there is little contrast present on the model’s skin.
The History of Lighting in the Arts
22
2-Point Lighting2-point lighting is the most common form of lighting that humans encounter in the natural world. With 2-point lighting, there is a key light and a fill light. The key is a natural source, such as the sun or moon. The fill is the net light from the key that bounces off nearby walls, ground, ceiling, and so on. 2-point lighting is found in the majority of landscape, figurative, and portrait paintings from the Renaissance to contemporary times that were created by artists wishing to capture accuracy in lighting. For example, in Figure 2.10, landscape and figurative paintings feature 2-point lighting.
Chapter 1Chapter 2
Figure 2.9 Top left: Rue de la
Chaussée à Argenteuil / Place
à Argenteuil, 1872, by Alfred
Sisley. Top right: Tulip fields in
Holland, 1886, by Claude Mon-
et. Bottom: Christus am Ölberg,
before 1510, by Jan Gossaert. In
each of these examples, there
is a natural key light, the sun or
the moon, and a fill light that
arrives as bounce light from a
direction opposite the key. The
fill light is visible in the shadow
areas or unlit sides of the
buildings and people.
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2-Point Lighting in PortraitureAs mentioned, 2-point lighting is a common lighting scenario for portraiture. For example, Figure 2.10 features two paintings. Key and fill light direction are roughly indicated with arrows.
Portraiture using 2-point lighting persists to this day and can be seen in photographs, motion picture film, and digital video. Variations in this lighting have been codified by photographers, cinematographers, and videographers. The variations carry names that describe the light set-up. These are described in the following sections.
Rembrandt LightingThis lighting variation is named after Rembrandt van Rijn, who incorporated a distinct lighting and shadow pattern in numerous paintings. With these paintings, a key light is set high and to one side, forming a triangu-lar patch of light on the opposite cheek of the subject (Figure 2.11). The fill light arrives from the side opposite the key and is key light bounced off a nearby wall. In Figure 2.12, a Rembrandt painting is compared to a contemporary portrait photograph, which used the same lighting technique.
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Figure 2.10 Left: Portrait of a Man with a Medal of Cosimo the Elder, c. 1474, Sandro Botticelli. Right: Portrait of François André
Vincent, 1795, Adélaide Labille-Guiard. These two paintings feature similar 2-point lighting despite the differences in the outdoor
and indoor locations and orientations of the subjects’ faces.
Key
Key
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The History of Lighting in the Arts
232323323323232323232223223
“The artist vocation is to send light to the human heart” —George Sand
24
Chapter 1Chapter 2
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Figure 2.12 Left: Detail of Portrait of Jan Harmensz. Krul, c. 1633, Rembrandt van Rijn. Right: Contemporary photograph using the same
lighting technique. The arrow points to the “Rembrandt patches,” which are triangular patches of light that form on the cheek opposite
the key light.
Figure 2.11 Set-up for Rembrandt lighting. The shadow from the nose is dependent on the height of the key
light. The fill light may be bounced key light or a second, weaker artificial light source.
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The History of Lighting in the Arts
Loop LightingLoop lighting is similar to Rembrandt lighting. However, the key light is lower and closer to the subject and thus forms a smaller “loop” shadow under the nose (Figure 2.13). As such, the nose shadow does not touch the lips.
Note that photographers may use more than two lights to create Rembrandt or loop lighting. For example, it may be necessary to add an additional light to the background and not rely solely on bounced key light. Whereas Rembrandt was limited to natural light sources, photographers enjoy the flexibility of artificial lights. Rembrandt and loop lighting are sometimes referred to as 3/4 lighting.
Split LightingThis lighting variation splits the subject’s face so the key light and fill light each illuminates one half with the centerline running down the bridge of the nose (Figure 2.14). Hence, the key and fill lights are opposite each other at roughly the same height.
Figure 2.14 Left: Set-up for split lighting with two lights on opposite sides of the subject. Right: Detail of frame from the motion picture The Color of
Money (1986).
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Figure 2.13 Detail of frame from the motion picture Dirty
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the nose of the actor.
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26
Chapter 1Chapter 2
Butterfly LightingButterfly lighting, which is also known as Paramount lighting, was developed by motion picture cinematog-raphers at Paramount Studios. This lighting variation places the key above and in front of the subject, creating a thin butterfly-shaped shadow under the nose (Figure 2.15). This is a form of glamour lighting that was devel-oped to impart the maximum amount of beauty to movie stars. Butterfly lighting is often paired with a strong secondary light in the form of a rim, hair, or back light.
Lighting that uses a key light that’s placed above the subject, such as Rembrandt and Butterfly lighting, is employed by stage in concert lighting that uses electrical lights (Figure 2.16). In these scenarios, the majority of lights are placed along trestles suspended above the stage.
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Figure 2.15 Left: Set-up for butterfly lighting. Right: Detail of frame from the motion picture Desire (1936). A key light, placed high, creates a butter-
fly-shaped shadow under the nose. The second light is a hair light arriving from behind the actress.
Figure 2.16 Butterfly lighting produced by stage lighting. You can identi-
fy the location of the key lights by examining the shadows.
Key
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The History of Lighting in the Arts
Broad and Short LightingBroad lighting and short lighting do not refer to light placement. These terms indicate which side of the subject’s face receives the key light and whether that side is turned toward the viewer or turned away from the viewer. With short lighting, the side of the face receiving the key light is turned away from the viewer (left side of Figure 2.17). With broad lighting, the side of the face receiving the key light is turned toward the viewer (right side of Figure 2.17). In general, the key light in a broad lighting setup is closer to the viewer or camera than a key light in a short lighting setup.
High- and Low-key LightingHigh-key and low-key lighting refer to the balance of light intensity between the key and fill light. You can describe each of these scenarios with a lighting ratio, which relates the intensity of the key light to the fill light. The lighting ratio is expressed with the formula key intensity: fill intensity. For example, a high-key lighting setup may have a ratio of 1:1 where the key light and fill light is equally intense. Other high-key ratios might be 2:1 or 3:1, where the key light is twice or three times as bright as the fill. With high-key lighting, there is rel-atively little contrast. High-key lighting is a common staple of glamour and fashion photography, stage-bound comedy television series (sit-coms), motion picture musicals, and commercial advertising. In each of these examples, the goal is to create a positive, cheery, uplifting, or wondrous mood (Figure 2.18).
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Figure 2.17 Detail of two frames from the motion picture Dirty Harry (1971). Short lighting is demonstrated in the left frame and broad
lighting is demonstrated in the right frame.
272727272772727272722727727227
“I didn’t know I was doing film noir. I thought they were detective stories with low lighting!” —Marie Windsor
28
Chapter 1Chapter 2
Low-key lighting takes the opposite approach and creates a great deal of contrast. Low-key ratios may range from 4:1 to 8:1. The ratio may be so extreme that the fill light is almost imperceptible. Low-key lighting is used to generate a mood or foreboding, unease, depression, stress, and similar negative feelings (Figure 2.19). Hence, low-key lighting is commonplace with horror films, crime dramas, and film noir (American thriller and detective motion pictures made from the mid-1940s to the mid-1950s).
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Figure 2.19 Left: Detail of frame from the motion picture Halloween (1978). Low-key lighting in a split lighting variation, where two equally strong
key lights arrive from the left and right side of the actor. Right: Detail of frame from the motion picture Double Indemnity (1944). In the classic film noir
style, low-key lighting is used throughout the film. With this frame, the actress is lit with Rembrandt lighting and the actor is lit with split lighting.
Figure 2.18 Detail of frame from the motion picture The
Wizard of Oz (1939). The actors are front-lit, allowing
their expressions of awe to be seen clearly. The lighting
ratio is 2:1, creating high-key lighting.
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The History of Lighting in the Arts
In the world of art, low-key lighting is present in the chiaroscuro works of Georges de La Tour, Jan Gossaert, Rembrandt van Rijn, Michelangelo Caravaggio, and similar Renaissance painters (Figure 2.20). You can see additional examples of low-key lighting in Figure 2.6 and the bottom of Figure 2.9 earlier in this chapter. High-key lighting is seen in a majority of painted portraits when it was important to present the subject in an attractive manner. You can see additional examples of high-key lighting in Figure 2.10.
Figure 2.20 Left: Detail of Head of an Old Man, c. 1629, Rembrandt van Rijn. Right: Detail of Szene: Berufung des Hl. Matthäus, 1599-1600, Michelange-
lo Caravaggio. There are two examples of low-key lighting in painting.
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Hard and Soft Lighting
Hard lighting and soft lighting refers to the type of shadow produced by a light. Soft lighting creates a soft-edged shadow. Hard lighting creates “sharp” or clearly-defined shadow edges. You can use each lighting type to create a stylistic look or to set a particular mood. For example, in Figure 2.21, similar photographs tap into different moods with the help of these shadows.
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“Italian cameramen grow up immersed in an awareness of light. It is part of theirmythology.” —Barbara Steele
30
Chapter 1Chapter 2
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Figure 2.21 Two photos taken by the same photographer generate different moods. Both photos are taken with out-
door lighting. The left photo features hard shadows created by the sun arriving from the top-left of frame. The right
photo features soft shadows, disguising the exact origins of the lighting. The lighting, in combination with facial
expressions, make-up, and costume can make similar subjects appear dark and dangerous or warm and inviting.
Soft shadows are a product of diffuse light. That is, the light either becomes diffuse over dis-tance or is diffuse because the light itself is physically broad. Small artificial light sources, such as light bulbs, are naturally diffuse because they generate light rays in an omni-directional fashion. As such, the softness of the shadow edge increases over distance (Figure 2.22). Broad artificial light sources, such as fluorescent light bulbs, neon tubes, signs consisting of numerous smaller bulbs, and LED televisions or monitors, essentially operate as an array of omni-directional lights, allowing numerous clusters of omni-directional light rays to overlap. In contrast, hard shadows are a product of lights that produce parallel light rays. The light rays that arrive on the Earth from the sun are virtually parallel. Some artificial light fixtures, such as those designed for stage or film lighting, are physically focusable so that their light rays become parallel.
Note that the light rays from a 3D point light or 3D spot light are generated from an infinitely small point in space. In contrast, real-world equivalents have non-0 dimensions due to the light bulb of bulb housing. Hence, the 3D light may need to be given an artificial width or radius so that they create realistic shadows.
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Figure 2.22 A 3D point light with a small radius
creates a shadow that becomes softer over
distance. The arrows represent several light rays
that pass close to the same point on the sphere’s
surface. The rays do not strike the sphere and
thus survive to contribute light to the planar sur-
face. Each ray interferes with the shadow created
by the neighboring ray, thus preventing the sharp
shadow edge from forming.
31
3-Point Lighting3-point lighting adds a third light in the form of rim light (Figure 2.23). Rim lights are also referred to as back lights or hair lights. 3-point lighting is useful for lighting people and is sometimes used for portrait photog-raphy, television interviews, and similar documentary or news gathering projects. By adding a third light to a 2-point lighting set-up, the subject is clearly separated from the background.
3-point lighting is often cited when discussing lighting for 3D animation; however, it has only limited applica-tions and can be difficult to apply to complex scenes that emulate real-world locations. Figure 2.24 and 2.25 illustrate two examples.
The History of Lighting in the Arts
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Figure 2.23 Left: Common 3-point lighting set-up. Right: 3-point lighting seen on television interview. The rim light prevents the man’s jacket from
disappearing against the black background on the left side of frame. Note that the lights have a high elevation and are most likely mounted on an
overhead trestle. As a general rule of thumb for non-stage lighting, the fill light is set to a height opposite the key; if the key is high, the fill is low, and
vice versa.
Key
Fill
Rim
Figure 2.24 Detail of frame from the motion
picture Shrek (2001). Close-up of Shrek lit by the
author. The blue rim light is very subtle and can
be seen on the wings of the vest, the top of the
head as a blue highlight, and the top edge of the
frame-right shoulder. The rim is stylistic and does
not match similar real-world daylight. The key and
the fill light form Rembrandt lighting.
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3-point lighting is rarely seen in traditional art. If the art features a rim light, it usually emulates light arriving from the sun or moon (Figure 2.26). In the real-world, we generally see a rim light as part of a 2-point light set-up. For example, the sun arriving from behind the subject forms a rim and serves as the key light; the fill light, arriving from the front, is bounced key light (Figure 2.27) .
Chapter 1Chapter 2
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Figure 2.26 Left: Detail of Christus am Ölberg, before 1510, by Jan Gossaert (you can see the full size version in Figure
2.9). A rim light appears on the wings of the angel and edges of the clouds, courtesy of the moon. Right: Detail of
Herkules vernichtet den Löwen von Nemea, 1634, Francisco de Zurbarán. A rim light appears along the back and tail
of the lion, courtesy of the sun or moon arriving from the background sky.
Figure 2.25 Frame from the motion picture Brave (2012). A red key light arrives from frame left. A blue fill light arrives
from frame right. A distinct rim light appears along the edges of the characters and is motivated by an unseen fire
that sits in the center of the character group. In a similar real-world location, the rim would not be as clearly defined.
In particular, a fire light would not produce lit edges along the front folds of the heroine’s dress or the back edge of the
bear.
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3-Point Lighting with a Background LightA common variation of 3-point lighting replaces the rim light with a light placed on the background. This is a common lighting scenario in traditional painting and serves the purpose of separating the subject from the background. For example, in Figure 2.28, a bright background sky and a bright background curtain help to define the edge of each subject.
The History of Lighting in the Arts
Figure 2.27 A rim light appears as a thin, bright line
along the legs, hair, hat, and left arm of the woman.
The rim is created by the sun setting behind the wom-
an on the left side of the frame. The second light, a
strong fill arriving from the front, is sun light bounced
off the surrounding ground and bench. Note that
the green of the bench is reflected onto the woman’s
outfit, which is a result of color bleed.
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Figure 2.28 Left: Detail of The Blue Boy, Portrait of Jonathan Buttall, c. 1770, Thomas Gainsborough. The bright patch of sky prevents the man’s
torso from blending into the background. Right: Detail of Portrait of Mrs. Sarah Siddons (1755-1831), 1785, Thomas Gainsborough. The bright
patch of red curtain is the only element defining the shape of the woman’s hat.
34
You can also see this lighting variation in photography, cinematography, and videography (Figure 2.29). With a painting, the light on a background may be an artifact of the key light. In contrast, modern art forms may require that separate, physical lights be aimed at the set or background behind the subject.
Other Limited Light VariationsA set-up that employs key, fill, rim, and background lights is sometimes referred to as 4-point lighting. In con-trast, the use of a background light and no other light leads to 1-point, silhouette lighting (Figure 2.30).
Figure 2.29 Detail of two frames from the television series Better
Call Saul (2015- ). The actors are separated from the background
by adding light to the background set. This serves as a variation of
3-point lighting. In both examples, the fill light is extremely weak,
creating low-key lighting,.
© 2
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Figure 2.30 Detail of frame from the motion picture Big Combo (1955). A background light illuminates smoke, silhou-
etting the actors and creating 1-point lighting.
© 1
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Chapter 1Chapter 2
35
Another light variation uses a kicker. A kicker is similar to a rim light; however, a kicker is often allowed to extend farther across the subject’s visible side (Figure 2.31).
A key light may be restricted to a small area. When used on a subject’s face, this becomes an eye light. Although verging on stylistic, this lighting technique accentuates the actor’s eyes and may be considered light arriving from a small window or similarly restricted source (left side of Figure 2.32). A restricted light that creates a streak, on a subject or on a background, is sometimes called a slash light. On the other hand, a catch light is a light intended to create specular reflections within a subject’s eye but not necessarily light the subject. A key light may also be given a pattern by aiming it through Venetian blinds, gates, fences, tree leaves, and other varied obstacles (right side of Figure 2.32). (A gobo, cucoloris, or cookie is a piece of stage equip-ment designed to block light with cut-out patterns.) A light may be aimed at a particular part of a background or set as a stylistic highlight; I will refer to this type of light as pool light as it creates a “pool” of light.
Figure 2.31 A kicker illuminates the frame right side of a man’s
neck and chin. Unlike a traditional rim light, the kicker is not
limited to a narrow strip of light.
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Figure 2.32 Left: Detail of frame from the motion picture Dracula (1931). A key light is restricted to the area of the eyes. Right: Detail of
frame from the motion picture I Wake Up Screaming (1941). The key light is aimed through a decorative grate.
Left
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The History of Lighting in the Arts
36
Naturalistic LightingComplex lighting may require more than four lights. This is particularly true when you are attempting to light a vast or intricate real-world space or recreate the pre-existing lighting of such a space. These lighting scenarios often require a naturalistic approach. As such, the goal of naturalistic lighting is to light realistically so that the subject appears in its natural state. In the traditional arts, naturalism, realism, and photorealism styles attempt naturalistic lighting. In terms of painting, Jan van Eyck was an early adopter of naturalistically-painted lighting (Figure 2.33).
In the realm of videography and cinematography, naturalistic lighting can present a challenge. The limitations of the camera technology may require the addition of lights to the location or set to capture a usable expo-sure. The addition of lights may lead to unwanted shadows, reflections, or highlights. A common example is a light source that unrealistically casts multiple shadows of itself (Figure 2.34). (This is less of a problem with 3D animation, where you can disable shadows for particular lights).
Figure 2.33 Detail of Madonna des Kanzlers Nicholas Rolin, 1435, by Jan van Eyck. The painter went to great lengths to
capture naturalistic lighting with soft day-lit shadows.
Figure 2.34 Detail of frame from the motion picture
North by Northwest (1959). Arrows point to two
shadows of the lamp that are unmotivated (lack a
clear origin). Such overlapping shadows are common
on sets used for 20th century motion pictures and
are a result of additional lighting required to properly
expose the film frames.
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Chapter 1Chapter 2
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The advent of modern camera and light equipment and digital capture technology has made the use of natural lighting (lighting already present at the real-world location) more feasible. For example, Stanley Kubrick made extensive use of natural lighting, which included sunlight, reflected sunlight, and light fixtures appropriate for the location, such as candles and lamps (top of Figure 2.35). More recently, Alejandro González Iñárritu used the wide exposure range available to digital cinema cameras to shoot at outdoor locations with a minimum of artificial lighting (bottom of Figure 2.35).
Figure 2.35 Top: Detail of frame from the motion picture Barry Lyndon (1975). This scene was shot with candle light
as its only light source, appropriate for a historical drama set in the 1700s. Bottom: Detail of frame from the motion
picture The Revenant (2015). Despite the dim light of an overcast sunset, the actors are clearly seen.
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The History of Lighting in the Arts
3337373737373737
“Throughout my pictures I employ lighting which is not naturalistic.” —Douglas Sirk
38
Chapter 1Chapter 2
Even with modern technology, the sole use of natural lighting may not be technically feasible or aesthetically desirable. Hence, there may be a necessity to use complex lighting set-ups. For example, in Figure 2.36, a room with natural sun light is lit with additional light rigs. Reflectors, flags (light blockers), and diffusion (translu-cent surfaces used to create soft light) are also employed to further control and accentuate the natural light. Artificial lights may even be placed outside the windows to make the arriving sun light appear even stronger. Despite the additional lights and rigging, the goal of the lighting is to produce a naturalistic look, whereby the room appears to be lit solely by the sun. This particular lighting set-up does not match any standard lighting scenarios discussed thus far, such as 2- or 3-point lighting. Hence, it’s not unusual for the lighting set-ups to vary greatly with each location, and even each shot, for feature films, television series, and commercials.
The use of natural lighting is intrinsic to cinematography and videography used for documentaries, television news gathering, and reality shows. With such projects, the crew and equipment is kept to a minimum as not to interfere with the real-life activities of the subjects. The exception with such cases is lighting used for sit-down interviews, where 2- and 3-point lighting is often used. In contrast, lighting used for stage plays and concerts is rarely naturalistic. The technical nature of stage lighting generally creates a stylistic look with overlapping key lights and overlapping shadows. In addition, stage lights often produce a rapid intensity falloff (Figure 2.37). Hence, spot lights earn their name by creating “spots” of light.
3D animation does not use natural lighting (high-dynamic range, photo-based light rigs providing an excep-tion). Nevertheless, the lighting set-ups for animated scenes and shots may carry the same complexity and variations as their real-world counterparts.
Figure 2.36 A real-world location utilizes a mixture of natural light, artificial lights, and light rigging.
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Figure 2.37 Stage lighting with overlapping
spots of light.
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39
The History of Lighting in the Arts
Stylistic LightingStylistic lighting employs aesthetic stylization. As discussed in Chapter 1, the stylization has no desire to match the natural lighting of the real-world and is therefore the opposite of naturalistic lighting. As discussed in this chapter, stylistic lighting is often seen with stage and concert lighting. In addition, stylistic lighting is often present in horror, science fiction, and fantasy projects, which includes film, television, animation, and video games (Figure 2.38). The goal of stylistic lighting may be to generate a particular mood or create a fantastic, dream-like, or surreal look.
Stylistic lighting within the traditional arts would include any art that shies away from realism, including Cub-ism and abstract art. Stylistic lighting may match the complexity of naturalistic lighting and is dependent on the particular location of the story or the aesthetic goals of the production team. Stylistic lighting is discussed in greater detail in Chapter 7.
Figure 2.38 Detail of frame from the motion picture Suspiria (1977). The saturated yellow and red lighting lends a sense of dread and
unease to this horror film.
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A Note on Video Games and Stop Motion AnimationVideo games and stop motion animation presents two unique types of lighting. Many video games al-low the user to move through a pre-lit environment or an environment that uses real-time simulation of site-specific lighting. As such, the point-of-view is constantly changing. Hence, the lighting often appears similar to documentary footage, where the viewer is immersed within a location. In terms of execution, video game lighting is similar to television or stage lighting where a large set or location must be lit in advance. The exception to this rule is the presence of video game cinematics. Cinemat-ics use pre-determined points-of-view and animations. Hence, the lighting of cinematics is similar to motion picture lighting.
Stop motion animation, on the other hand, necessitates the use of real-world lights on a miniature stage. Therefore, lighting for stop motion can be discussed as it would for motion picture, television, or stage lighting.
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Chapter 3: Lighting in 3D
When it comes time to light in a 3D program, it can be useful to follow organized steps to achieve aesthet-ic lighting in an efficient manner. The steps include determining what lights are needed and what types of shadows are necessary. It’s also useful to be familiar with common 3D shaders and how their basic properties function.
This chapter includes the following critical information:
• Suggested 3D lighting workflow • Common 3D light types, shadow types, and properties • Common shaders and properties
Photo copyright Rungaroon Taweeapiradeemunkohg / 123RF Stock Photo.hoto.
42
3D Lighting Pipelines and WorkflowAlthough lighting in a 3D program shares many similarities to lighting for the fine arts, stage, film, video, and photography, it requires its own unique workflow. When the workflow is handled by a team of animators, it’s often referred to as a pipeline. A pipeline is a standardized system of producing complex animations using teams of artists and an array of equipment and software.
For example, a pipeline created for an animated feature or extensive visual effects project generally follows these production pipeline steps:
1. Concept art: Characters, props, environments, and color guides are designed.2. Storyboarding: The story is broken into specific shots with specific camera placements using 2D drawings or simplified 3D animations. If the 2D drawings are animated and edited into a video, the result is referred to as an animatic.3. 3D modeling: Characters, props, and environments are constructed in 3D.4. Texturing: Models are textured.5. Rigging: Models that require animation are rigged so they can be moved or deformed.6. Layout: The storyboards are translated to 3D set-ups using the 3D models.7. Animation: Characters, props, and effects (such as fire and water) are animated.8. Lighting: Animated shots are lit and rendered.9. Compositing: If required, shots are composited in 2D to combine and/or fine tune the renders.
Depending on the studio and the scope of the production, some of these steps may overlap or happen simul-taneously. In addition, all of these steps require testing and revisions. Compositing may be the domain of the lighter or it may be handled by a separate compositing department.
If an animation is small in scope, one animator may handle multiple tasks. For example, on an independent animation or a commercial production with a limited number of shots, one animator may model, texture, rig, animate, light, render, and composite everything needed for one shot.
Whether or not an animation is part of a large or small project, it pays to follow certain steps when lighting. These include the collection of light information, an organized approach to placing and adjusting 3D lights, and an efficient method of test rendering. To help facilitate lighting, it helps to understand the difference between light and shadow types and basic shader functionality.
Collecting Light InformationThe first step to 3D lighting is to determine how many lights you need, where the lights should be located, and what properties the lights should possess. To derive this information, ask yourself these questions:
What is the context of the lighting? Are you lighting a single, standalone shot or are you lighting one shot of a multi-shot scene? Are you lighting all the shots in the scene or do you need to match your work to other lighters who are undertaking surrounding shots? The answer to these questions determines what reference is required and if any precedents have been set for the lighting you are working on. For example, on a feature animation, you may need to match shots lit by other lighters and follow general guidelines set by the art department through concept art and color guides.
Are there any special considerations? Is there an impetus to light stylistically? Is there a need to light in a special way to communicate story information or establish a mood? These considerations may affect the answers of additional questions.
Chapter 3
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What is the location of the lighting? Is the location on Earth? If so, the lighting should follow basic qualities of light in Earth’s atmosphere. If not, light may react differently. For example, if you are lighting a scene in space, the lack of air molecules or particulate matter, such as water vapor, prevents a light beam from forming through light scatter (Figure 3.1). This is not to say that lighting should always be scientifically accurate, but lighting generally needs to be perceived as appropriate for a particular location. If the plan is to light stylistically, the precision of the light sources may not be critical. For example, numerous science-fiction films show laser beams and terrestrial explosions occurring in space. Nevertheless, stylistic lighting has its own aesthetic concerns, which are discussed later in this book.
What is the location more specifically? Is the location inside? For example, the location may be in a bedroom, a car, or a cavern. Conversely, is the location outside? The specific location affects what lights are available and expected to be present by the viewer.
Does the location exist? Does your lighting need to replicate a real location? As such, do you possess reference in the form of photos or video? If your location does not exist, does it need to match a similar location?
What is the time of day? Is it sunrise, noon, afternoon, sunset, evening, or nighttime? If you combine this information with the location, you can determine what light sources would be generally available at the location in the real world. For example, if the location is a city street, the main source of light during the day is the sun (Figure 3.2). At night, the source of light may be the moon, street lamps, car headlights, electric signs, and so on.
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Figure 3.2 One location with two times of
day, necessitating different light sources.
Note that the nighttime lighting includes
lens flares (light scattering through the
optical components of the camera lens) and
light trails (created by long exposures of
moving car headlights and tail lights).
Lighting in 3D
Figure 3.1 The red light of a laser illuminates a
lab. The beam itself is visible due to particulate
matter in the air, which would otherwise be
missing in a vacuum.
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What is the time period? Does the lighting scenario take place in the present? If not, what is the historical time period in which the lighting occurs? The year in which the scene takes place affects the list of available lights. For example, a pre-20th century setting prevents the existence of incandescent light bulbs and requires more extensive use of fire-based lights, such as candles, oil lamps, torches, and so on. Because each type of light has distinct properties, this affects the way in which you light within the 3D program. If the time period has no historical basis or is derived from an imaginary alter-native history, you can mix and match light types. For example, you may insert artificial light sources into a location where they would otherwise be historically unavailable. By the same token, you can invent light sources if historical accuracy is not needed. For example, light may arrive from the magic staff of a wizard.
What are the properties of the light sources? After you’ve determined what light sources exist, you can define the lights’ specific properties. For example, the lights may be natural or artificial. Natural light may include the sun, sunlight reflected off the moon, a fire, or a candle. Artificial lights come in many forms, such as incandescent light bulbs, fluorescent light fixtures, neon signs, LED light arrays, and amplified bulbs contained in flashlights or headlamps. Each of these light types possess a real-world color (courtesy of a specific wavelength), intensity (brightness), focus (parallel, oblique, or random light rays), and shadow type (hard-edged, soft-edged, or hard-to-soft over distance).
Lighting Determination ExamplesTo practice the technique of determining light sources, you can study existing photographs, film and video stills, or paintings. For example, Figure 3.3 represents an example of simple, real-world 2-point lighting. Ques-tions and answers are included.
What is the location? An office.
What is the location more specifically? The center of a window-lit room.
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Figure 3.3 A man in an office is
lit with 2-point lighting. Letters
indicate locations of different
light sources.
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Does the location exist? Yes.
What is the time of day? Daytime. The time may be mid-morning or mid-afternoon based on the longish shadows cast by the people in the background. A time closer to noon would create shorter shadows. A time closer to sunrise or sunset would create longer shadows with dimmer, more saturated light.
What is the time period? We can assume this is present day as there are no obvious anachronisms.
What are the properties of the light sources? The light sources are as follows:
A) The sun as a key light. This light arrives from the bank or large windows at the left of frame. The sunlight arrives at a roughly 45 degree angle, creating longish shadows. The sunlight is also angled toward the man so that the light reaches the front of his face, forming split lighting. The light, by the time it reaches the man, is a soft light that does not cast a strong shadow on the man himself. The softness may be a result of the sunlight scattering through curtains or multiple, semi-obscured windows.
B) Fill light. The weaker, secondary light source arrives from the lower-right side of the frame. This is sunlight that has bounced off the floor and surrounding walls. There are no other visible light sources, so we can safely assume that the bounced sunlight is the sole secondary source.
As a second example, we’ll look at a complex, fantastic, multi-point lighting (Figure 3.4).
Figure 3.4 Detail of
Antoniusaltar, Triptychon,
Mitteltafel: Versuchung
des Hl. Antonius,1505-06,
by Hieronymus Bosch. A
fantastic scene nevertheless
gives clues to lighting. Letters
indicate locations of different
light sources.
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What is the location? Outdoors, near the outskirts of a city.
What is the location more specifically? Near the ruins of a church.
Does the location exist and what is the time period? Possibly. This may represent the Flemish home-land of the painter as it may have typically looked in the late Medieval time period (minus the mon-sters and conflagrations).
What is the time of day? Daytime, as indicated by the sky at the upper-right of the painting. However, the raging fire in the background has created so much smoke that part of the landscape is thrust into virtual night.
What are the properties of the light sources? The light sources are as follows:
A) The sun as a key light. A broad, generic light arrives from the center-left of the painting. This is indicated by shadows underneath and around the central characters as well as the general shading of the humans and monsters (where the upper-left side of many characters receive the most light).
B) Fill light. The weaker, secondary light source arrives from the lower-right side of the frame. Lack-ing other identifiable source, this is sunlight that has bounced off the ground and other nearby surfaces. You can see this light on the characters that are painted with greater contrast.
C) Background fire as a utility light. Although the fire does not affect the lighting of the foreground, it illuminates (and silhouettes) background buildings.
D) A light beam as a utility light. The narrow beam appears in the interior of a church. Although this could be the focused light of the sun, it seems out of place in this scene and is therefore stylistic.
E) Interior lights as utility lights. The open doors and windows of the background buildings appear illuminated from within. Keeping the time period in mind, you can assume the light is generated by fireplace fires, torches, or oil lamps. Alternatively, the raging fire that plagues the city may have reached the building interiors.
3D Lighting StepsAfter you’ve determined how many lights you need, where the lights should be located, and what basic prop-erties the lights possess, you can add them to your 3D scene. Regardless of which 3D program you are using and the exact method by which to create and manipulate the 3D lights, I suggest following these basic steps:
1. Add and position the key light. The key should serve as the most intense light source. Adjust the light intensity so that it does not overexpose the subject (left side of Figure 3.5). Overexposure will cause detail loss on the surface and may cause areas to appear pure white. Activate shadows for the light and adjust the show quality to match the type of light source. Adjust the light position to make the shadows fall in an aesthetic manner (right side of Figure 3.6). If a scene requires more than one key light, add and adjust these. Multiple key lights may be necessary if there are several intense lights in a scene, such as overhead light fixtures that are equally strong and distinctly separate.
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2. Add and position the fill light. A fill light may or may not require its own shadows (left side of Figure 3.6). For example, if the fill light emulates a light that bounces off a wall, a shadow may be so soft that it is not necessary to activate it. If the fill light emulates the bulb of a shaded table lamp, a distinct shadow is appropriate. If a scene requires multiple fill lights, add and adjust these. Note that the addition of each new light may require the adjustment of the previous lights. You may need to readjust all the light inten-sities so you don’t run into overexposure. To judge the contribution of a new light, consider toggling the light’s on/off property. Alternatively, you can assign lights to different 3D layers (if available) and toggle the layer visibility on and off.
Lighting in 3D
Figure 3.5 Left: A key light is positioned to illuminate a model. Right: Shadows are activated for the key
light. The addition of shadows often requires the repositioning of the shadow-producing light in order to
achieve an aesthetic result. With this example, the end result is loop lighting.
Figure 3.6 Left: A fill light is added so that it arrives from the lower-left side of frame at an intensity 1/4 that of the
key light, creating a 4:1 lighting ratio. Right: A spot light is added to strike the background to better define the edges
of the model. This serves as a variation of 3-point lighting with key, fill, and background lights.
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3. Add and adjust any utility lights. Add these lights to improve the overall aesthetic quality or to emulate specific light sources that are not as intense as the key or fill lights. For example, you might add a rim, kicker, hair, or background light to separate the face of a character from the background (right side of Figure 3.6). Alternatively, you might add lights to emulate a non-key, non-fill real-world light source, such as a flickering candle on a background shelf or a waning moon in a background sky.
Keep in mind that this is a general guideline and may not work in every lighting situation. Here are a few caveats:
• Lighting a model that is untextured may lead to different results when compared to lighting a model that is textured. An untextured model is one that remains assigned to a default shader. A textured model is one that has been assigned to a custom shader that has been mapped with texture bit-maps or procedural textures. Lighting an untextured model may necessitate lighting changes when the model is finally textured. This is due to light intensities appearing different on surfaces that possess dif-ferent colors, different levels of detail, and different shader qualities such as specularity or reflectivity. For example, the model seen in Figure 3.5 is assigned to a gray-colored default Lambert material. If the model was textured so that it possesses a skin-like quality, the light intensity values would require adjustment. For more information on shaders and the process of texturing, see the remaining sections of this chapter.
• The lights and shadows you are able to use are dependent on the 3D renderer you choose. Thus, as you go through this lighting process, you must consider which renderer and which renderer settings are the most appropriate for your lighting task. We will discuss this issue further in Chapter 5.
• Occasionally, it may be prudent to start lighting with fill lights or utility lights. For example, if you are lighting a character in the center of a large environment, it may be wise to light the environment first; this will help establish the overall look of the scene, which will help determine what light reaches the character.
Testing 3D LightingAn important part of the 3D animation process is rendering. When it comes to 3D lighting, you must render to create a final version of the frame or frames. You also have to render to test and adjust your lighting set-up. Although each 3D program offers its own set of features for rendering, here are a few things to keep in mind as you work:
• Light with the final composition. Light your scene based on the view of the rendering camera. In other words, don’t light while looking at the view of an arbitrary camera or a camera that has not been posi-tioned with a final composition in mind. If you fail to follow this rule, you may waste time concentrating on surfaces or shadows that are otherwise hidden or out of frame.
• If you are lighting an animation with motion, test the lighting on different frames. You may need to adjust the lights based on the motion. For example, if a character is moving about rapidly, you may need to reposition the lights to avoid unattractive shadows or add additional lights to ensure the character remains lit despite his or her movement across the frame.
• If possible, light with final shaders and textures. As discussed in the previous section, it may be diffi-cult to gauge the success of a lighting set-up if the models in the scene have not been textured. Ultimate-ly, 3D lights are dependent on the surface qualities provided by shaders. Shaders are discussed in more detail throughout the remainder of this chapter.
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• Use lighting shortcuts where available. 3D programs often provide various tools and functions to speed up the lighting process. For example, the 3D viewports may support shaded views with approxima-tions of the lighting and shadowing. Although the quality may not be as high as a final render, it can help you place lights more quickly. When it comes time to render a frame, either through a 3D viewport or a dedicated render window, you often have the option to render small regions. Regions allow you to con-centrate on areas that are affected by your lighting adjustments without having to calculate the lighting and shadowing for the entire frame. Some render windows or frame buffers support IPR (Interactive Pho-torealistic Rendering), where the render automatically updates as you adjust lights, shaders, or textures.
• Use lower render quality settings when you start. If you are roughing in the positions, intensities, and shadows of your primary lights, consider using a lower resolution or lower render quality to render test frames. This will help speed up the lighting process. As you approach a final lighting setup, you can return the resolution and quality to the requirements of the final output. If you are using a 2D compositing program with a 3D environment, such as Adobe After Effects, you can use a lower proxy resolution in the viewport to speed up the lighting calculations.
• Consider fine-tuning the shader properties yourself. If you are working on your own 3D project, it may be useful to adjust the shader properties along with the light qualities to create the best possible lighting result. If you are working with a team at a studio, this may not be possible due to the shared ani-mation pipeline. Nevertheless, it always pays to be familiar with the ways that shaders work in the presence of lights.
Working with Color Calibration
In the realm of digital imaging, color calibration is an important consideration. Digital imaging includes digital video, photography, art, graphic design, and 3D animation. All of these digital art forms are reliant on an RGB color model that combines different intensities of red, green, and blue to represent the full range of colors. When a digital image is created, it’s created within a color space, which is a range of colors the image can potentially store. When the image is displayed, however, it may encounter a device that utilizes a different color space. To complicate matters, different devices use different color spaces, which may lead to the image looking differ-ent on each device (devices will have a limited color range for one or more of the color channels within the color model). For example, a rendered 3D animation may look one way on a computer monitor and another way on a broadcast television. Color calibration attempts to neutralize this problem by adjusting the various devices to make the image appear consistent.
Color calibration can occur on the device level. For example, you can color calibrate your com-puter monitor using the operating system or specialized calibration software. It’s also possible to apply color calibration within the software creating the digital images. For example, some 3D programs allow you to activate color calibration so that your work is suitable for output to a par-ticular device (such as a television screen or theater projector). There are generally two different ways to apply calibration in a 3D program:
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Working with 3D LightsMuch like their real-world counterparts, you can position and aim 3D lights in a 3D program that supports lighting. In addition, you can adjust basic properties such as intensity, color, and shadow quality. Although each 3D program represents its 3D lights in a slightly different way (Figure 3.7), lights within these programs share many common traits, which are discussed in this chapter. Hence, you can apply this knowledge to a broad array of programs, including Autodesk Maya, Autodesk 3ds Max, Autodesk Softimage, MAXON Cine-ma 4d, and Blender. This also applies to 3D programs that are designed for specialty tasks such as sculptural modeling, effects simulation, industrial design, architectural visualization, and video game design. In addition, the common traits are carried over into 2D compositing programs that offer a 3D environment, such as The Foundry Nuke, Blackmagic Fusion, and Adobe After Effects.
Common 3D Light Types3D programs generally include a set of common lights that include the following:
Spot light This type of light is named after the real-world counterpart used in film, video, and stage lighting. Its light emanates from a point in space but quickly diverges over distance. The light rays are oblique (neither parallel or perpendicular), creating a light cone. The cone indicates the outermost vectors of the light rays. At the cone edge, the light intensity drops to 0. When the light hits a surface, it forms a circular or oval spot of light (Figure 3.8).
View Transform Allows you to activate a color space transform in a render viewport, win-dow, or buffer. Activating a view transform does not affect the render’s inherent RGB values. Instead the transform temporarily converts the native color space to a different color space. For example, most computer systems operate within a sRGB color space. The view transform can convert sRGB to Rec. 709, which is the color space of HDTV (High-Definition Television). Note that some view transforms include a gamma adjustment. Gamma, in the realm of digi-tal imaging, is a power function that adjusts displayed images so that they appear correct for human vision. Gamma-adjusted images appear to have greater contrast and a greater range of values.
Renderer Transform As opposed to temporarily applying a view transform to the render viewport, window, or buffer, you can choose to apply a color space transform at the point of render so that the rendered images are created within the new color space. This option is suitable if you are rendering for a particular set of devices, such as theater projectors.
When discussing color calibration, it’s also important to consider linear color space. Linear color space is a color space where gamma adjustment is not applied. Working in a linear color space allows for a more accurate representation of image values. Although not mandatory for successful lighting, linear color space may be required for accurate results when working with PBR (Physically Based Rendering) systems. Many 3D programs support a linear color space work environment. Switching to such a work environment generally affects the way in which texture bitmaps are interpreted and the way in which renders are displayed and exported. That said, the linear color space provided by a 3D program does not affect the color space used by the display device. Hence, using linear color space demands careful set-up and consideration. Using linear color space incorrectly may lead to inaccurate-ly-lit renders that will require additional manipulation outside the 3D program.
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You can adjust the cone width to increase or decrease the lit area. Additional spot light properties, such as penumbra angle, control the rapidity with which the light transitions from a non-0 to 0 intensi-ty. For example, a large penumbra value causes the spot of the light to have a soft edge. A 0 penumbra value causes the spot to have a hard (non-soft) edge. The cone of a spot light is usually included as part of the 3D light icon (Figure 3.8). The position and rotation of a spot light icon affects the quality of the light. (Note that position is generally referred to as translation within 3D programs).
Point light The light of this type emanates from a point in space. The light is omni-directional; that is, the light rays fan out in all directions (Figure 3.9). You can use this type to emulate position-specific artificial light sources like light bulbs or position-specific natural light sources like candles. The trans-lation of the point light icon affects the light quality but light’s rotation has no impact. Point lights are sometimes called omni lights. Note that some renderers treat point lights like emissive spheres, where they have a distinct size in XYZ space; this variation is more realistic and more accurately matches similar real-world light sources.
Directional light This type creates parallel rays of light as if arriving from an infinitely distant light source. You can use this light to emulate the sun or moon. The rotation of a directional light affects its light quality but its translation has no impact. The light icon indicates the direction the light rays are traveling through the use of arrows or directional lines (Figure 3.10). Directional lights are sometimes referred to as sun, infinite, or direct lights.
Figure 3.7 Left: Light icons in Autodesk Maya. Right: Light icons in Blender (the area light gains a rectangular icon when scaled).
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Figure 3.8 Left: A spot light illuminates a model. Yellow arrows indicate the direction of the light rays. The light’s cone angle is set to 20 (degrees).
Middle: The cone angle is set to 60. Right: The cone angle is set to 5 while the penumbra angle is set to 20. The positive penumbra angle value adds a
soft transition from the edge set by the cone angle in an outwards direction. Note that shadows have not been activated.
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Ambient light This light type produces an intensity that is equal at all points in the scene (Figure 3.11). Hence, the light’s translation does not affect the light quality (in fact, some programs do not bother to create an ambient light icon). Ambient lights are sometimes used as weak fill lights. Ambient lights are sometimes called radial or flat lights. In general, ambient lights have technical limitations, such as the inability to cast shadows or interact with specific shader functions, such as bump mapping.
Area light This light type is defined by a rectangular shape and acts like an array of diverging direc-tional lights or a cluster of point lights generating rays in a 180 degree sphere. Area lights don’t create rectangle spots or light pools due to the overlapping of light rays (Figure 3.12). That said, the larger the area light, the softer the edge of the light pool. You can use area lights to emulate broad light sources that are nevertheless confined by a shape. For example, you might use an area light to recreate the light arriving through a window, light arriving from a theater marquee, or light generated by a comput-er monitor. This is one of the few light types that is affected by scale changes. For example, you can use an area light to emulate a neon tube by making the light icon long and narrow. (In general, only X and Z scale changes alter the light.) Area lights are also referred to as light boxes. Note that some renderers support area lights with different shapes including discs and spheres.
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Figure 3.10 A directional light illuminates a model. The
light icon is drawn as a cluster of arrows with the arrow
heads indicating the direction the light rays travel. The
light reaches all points within the scene along a specific
vector. Hence, the rectangular ground plane is completely
lit. However, the side of the sculpture that is opposite the
light direction remains unlit.
Figure 3.9 A point light illuminates a model. The light is placed
in front of the model. Because no other lights are present, the
back side of the model is dark. Note that shadows have not been
activated.
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Figure 3.12 An area light creates a soft light pool. The icon “tail” indicates
the light direction. The yellow arrows represent a small portion of the
overlapping light rays generated by the light.
Figure 3.11 An ambient light equally illuminates all parts of a
model surface. Although useful as a fill, ambient lights are unable to
function as a key due to their lack of directionality.
Using Light Decay
Thus far, descriptions of lights assume that there is no light decay. Light decay represents the rapidity with which the light transitions from maximum intensity to 0 intensity over distance. This is also known as light falloff or light attenuation. These terms are somewhat confusing as real-world light does not lose energy or disappear as it travels through a vacuum. Instead, light and other electromagnetic radiation diverges from its source and thus, over distance, causes there to be less radiation in any given point in space as the radiation is spread out over a greater and greater area.
If light decay is not activated for a 3D light, the light’s intensity fails to change over distance and is as strong at 10 units as it is at 1,000,000 units. If light decay is activated, there is generally a way to control the decay rapidity. For example, you might switch to a mathematical decay formula such as quadratic. Quadratic decay uses an inverse square law, which describes light and other electromagnetic radiation in the real-world whereby the radiation intensity is inversely propor-tional to the square of the distance from the radiation source (left side of Figure 3.13). The law uses the formula light intensity = 1/distance2. In contrast, a linear or constant decay may be con-sidered stylized as its formula is intensity = 1/distance (right side of Figure 3.13). More aggressive decay may use a cubic formula where intensity = 1/distance3.
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Common 3D Light PropertiesAlthough the properties that control 3D lights in various 3D programs may have different names, their basic functionality remains the same (Figure 3.14).
Figure 3.13 Left: Graphic representation of the inverse square law. Light rays diverge over a greater and greater area. Right: Three
identical spot lights illuminate a plane. The top light has no decay, keeping light intensity consistent over distance. The middle and
bottom lights lose intensity over distance due to the application of light decay formulas.
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Figure 3.14 Clockwise, from top left:
A partial set of spot light properties,
as seen in Autodesk Maya, Blender,
Blackmagic Fusion, and Adobe After
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The most useful properties follow:
Transforms Lights generally carry transforms that include translation (position), rotation, and scale. Depending on the light type, some of these transforms have no impact on the light quality. For exam-ple, translation affects a point light while rotation affects a directional light. See the previous section for additional examples.
Intensity / Energy Lights include a property to control the light’s brightness. If this property is set to 0, the light is essentially turned off. Some programs, such as Autodesk Maya and Blender, support negative light values that reduce the strength of other, overlapping lights.
Color Lights include a place to change the light color, which allows the light to mimic real-world light sources with different wavelengths. For example, you might change the light color of a key to orange to mimic a sunset. Light color is generally multiplied by the light intensity, so that both properties affect the overall light strength. For example, if the light intensity is 1.0 but the light color is set to 0.5 gray, the end strength is 0.5 (1.0 x 0.5). Light color properties are usually defined in RGB, where there is a value for red, green, and blue. Some lights accept color temperature values measured in kelvin.
Shadows Many lights can cast shadows and offer a means to activate the shadows. There are several different methods of generating shadows in 3D programs—these are discussed in the next section.
Decay Rate / Decay Type / Attenuation Some lights support light decay and different methods to control the rate of decay (see the previous sidebar). In addition, a Falloff Distance / Distance property may be included so you can set the distance at which the decay begins.
Emit Specular / Emit Diffuse Some lights allow you to turn on or off the lighting functions for diffuse lighting calculations and specular lighting calculations. In this situation, diffuse refers to diffuse reflectivity, where light reflects from the surface, thus making the surface color visible. Specular refers to specular reflections that create specular highlights, which are cohesive reflections of bright light sources. Specular calculations are necessary to create reflections when ray tracing.
Different light types may carry different sets of properties. For example, spot lights include additional proper-ties to control their light cones:
Cone Angle / Hotspot This sets the width of the cone.
Penumbra Angle / Cone Feather This sets the width of the transition for maximum intensity to 0 in-tensity at the cone edge, as seen on surfaces the light strikes. In general, if this property is positive the softness extends outwards; if this property is negative, the softness extends inwards.
Cone Falloff / Dropoff Some spot lights include properties to control the light decay from the light center to the cone edge. This functions independently of the penumbra angle.
Barn Doors / Square Some spot lights carry the option to turn the circular cone into a rectangular one. This is apparent when the light creates a rectangular light pool on surfaces it strikes.
Note that some terms may have different connotations in different programs. For example, in 3ds Max, Falloff sets the size of the penumbra angle while in After Effects, Radius set the penumbra angle and Falloff controls the light decay.
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Shadow Variations Among LightsShadows are a critical part of lighting. Every real-world light source produces shadows when encountering opaque or semi-opaque objects. As discussed, a shadow is an area that receives no light. In fact, the shadowed area is a three-dimensional volume behind the object opposite the direction the light is traveling. That said, we usually encounter two-dimensional shadows on surfaces as the atmosphere is transparent (left side of Fig-ure 3.15). However, if fog, smoke, haze, or similar participating media (suspended particles that reflect light) is present in the air, you can see the three-dimensional shadow form (middle and right side of Figure 3.15).
The quality of a shadow varies with the type of shadowing light. This is true whether the light is in the real world or in a 3D program. For example, the real-world sun and 3D directional lights produce parallel shadows (Figure 3.16). Note that the parallel quality may be difficult to detect in the real-world due to perspective (as is the case with the middle photo in Figure 3.15). Technically speaking, the sun is an omni-directional light source, sending light rays in all directions out into space; however, only a narrow band of rays reach earth, making them, for practical purposes, parallel.
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Figure 3.15 Left: A clearly-defined two-dimensional shadow is cast on the ground by the sun. Middle: Three-dimensional shadows are revealed as
the sun casts shadows through haze surrounding trees. The shadows appear as dark streaked lines. Right: A three-dimensional shadow is formed
underneath a sphere when 3D fog and a shadow-casting spot light is used.
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Real-world spot lights and unfocused light bulbs produce oblique (non-parallel and non-perpendicular) shad-ows, as do their 3D spot light and point light counterparts (Figure 3.17). Note that the resulting 3D shadows may be hard-edged unless special steps are taken. The hard edge quality is a result of the spot or point light producing light rays from a single point in space. This prevents the overlapping of rays at the shadow edge. To create shadows with soft edges or edges that degrade over distance, you must use a broad light. If you are using ray trace shadows, you can emulate this by increasing the light’s width or radius property.
Alternatively, to create shadows that soften over distance, you can use an area light. Area lights, due to their ar-ray-like structure with myriad light rays that overlap, produce soft-edged shadows by default. The edge quality changes based on the size of the area light and its distance from the point being shadowed (Figure 3.18).
Lighting in 3D
Figure 3.17 Left: Oblique shadows cast by a spot light with a wide cone. Middle: The same ray trace shadows are given a large radius property value,
allowing the shadows to become softer over distance. Right: The spot light’s cone angle is reduced and the light is moved farther away from the
cylinders, thus creating longer and less oblique shadows.
Figure 3.18 An area light, set close to
the cylindrical objects, creates shadows
that soften over distance. Note the
degree to which the shadows diverge
from each other. If the area light was
placed farther away, the shadows
would become more parallel.
58
Chapter 3
Shadow ApproachesWhen it comes to generating shadows, there are several methods employed by 3D programs:
Depth Map This shadow type renders a depth map from the point-of-view of the shadow-producing light. The distances of objects from the light are encoded as scalar values and appear in grayscale (Figure 3.19). The depth map is used by the renderer to determine what lies in shadow and what does not. Depth map shadows have the advantage of being efficient; however, they have quality limitations as they are dependent on a rendered map with a fixed resolution. They also allow for less control of the shadow edge, where the shadow edge is equally hard or soft along its entire length. Many light types are able to produce depth map shadows as the shadows are perhaps the most common shadowing method provided by 3D programs. Depth maps are also referred to as depth buffers or Z-buffers. Depth map shadows generally have two main properties: resolution, which sets the depth map bitmap size, and a second property to filter the shadow edge and control its hardness or softness. The name of the second property has many variations—for example, filter size, sample range, and softness.
Ray Trace This shadow type is supported by ray tracing renderers. Ray tracing traces the path of rays through a camera image plane until they intersect 3D surfaces. The rays reflect off the surfaces, trans-mit through surfaces, or are absorbed by the surfaces (the ray killed off), based on the properties of the shaders assigned to the surfaces. Hence, ray tracing is able to create accurate reflections and refrac-tions. Ray trace shadows are generated by shooting shadow rays from the point of a surface intersec-tion to a shadow-casting light. If the shadow ray encounters a surface on the way to the light, then the original surface point is known to be within a shadow (Figure 3.20). Ray trace shadows are more com-putationally expensive than depth map shadows, but are generally more accurate. In addition, they are not dependent on an arbitrary pixel resolution. Note that ray trace renderers work in a direction opposite the real-world. In the real-world, photons are generated by a light, reflect off surfaces, and eventually reach the camera sensor or viewer’s eye. Nevertheless, the backwards ray tracing method is mathematically efficient as it does not waste energy on light rays that reflect off surfaces and never reach the camera due to their unique vectors. For an example of 3D ray trace shadows, see Figures 3.16 and 3.17 in the previous section. Ray trace shadow functions generally include properties to control the virtual width or radius of the shadow-casting light (sometimes called radius, angle, spread, or soft size) and overall quality (sometimes called shadows rays, samples, or quality).
Figure 3.19 A depth map of a latticed cube, which is a grayscale
view from a shadow-casting light. With this variation, surface
points closer to the light are rendered darker.
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Figure 3.20 A simplified representation of ray trace rendering and ray trace shadowing.
PBR (Physically Based Rendering) I’ll use this category to describe advanced lighting and rendering systems that take into account light bounce and color bleed. These systems produce shadows auto-matically as light rays and/or virtual photons are traced through a scene, accounting for reflections, transmissions, and absorptions when encountering surfaces. As such, specific shadow-casting lights are not required (although the systems also support depth map and ray trace shadows). However, if photon-tracing is necessary, 3D lights that can generate photons are required. These rendering sys-tems are discussed in more detail in Chapter 5.
Renderer Variations 3D renderers often offer specific variations of common shadow types with additional controls to add more flexibility, efficiency, or render quality. For example, Solid Angle Arnold provides extra light controls that define shadow quality. The host 3D programs include documentation for using these variations.
Specialized 3D Light Types
In addition to spot, point, ambient, directional, and area lights, other specialized 3D lights may be provided by a 3D program. A few of these are discussed here:
Mesh Some 3D renderers are able to convert user-defined geometry into a light source. This may be useful for emulating a frosted light bulb, translucent lamp sconce, a fluorescent bulb formed into a ring, or a complex neon tube (Figure 3.21). In this situation, light rays are shot out from the geometry surface at perpendicular angles (along the surface normals).
Camera
View Plane
View Rays
3D Surface
Shadow Ray
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Light Origin
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Cylindrical This light type takes on the form of its namesake. It’s related to a mesh light in that it acts like an array of directional lights aligned to the cylinder surface normals. You might use this light to emulate a straight fluorescent bulb.
Environment This light type is presented as a 180 or 360 degree sphere. The sphere acts as an array of directional lights that point inward. You can use the light to emulate a daytime sky. The light may be considered to exist infinitely far away or, if the option is present, can be used with specific scale and translation within the 3D scene. If you are employing an advanced lighting or rendering system, you can base the light intensity and color on a bitmap texture that is mapped to the sphere. Environment lights may be included with the standard light set or may be provided by the renderer as a special shader (Figure 3.22). 180 degree environment lights are also known as hemi, dome, skydome, or sky-light lights. This light type is demonstrated in Chapter 5.
Chapter 3
Figure 3.21 A curly, polygonal tube is converted to
a light source by the Arnold renderer in Autodesk
Maya. By default, quadratic light decay is used. Soft
shadowing is intrinsic to the geometric light source
due to a multitude of overlapping light rays.
Figure 3.22 Left: An NVIDIA Iray IBL (Image-Based Lighting) sphere surrounds a primitive cube. The IBL shape is provided by a light shader and is
designed to derive intensity and color information from a mapped bitmap image. The sphere is designed to surround the scene to be lit. Middle:
Same IBL sphere with viewport shading turned on, revealing the mapped bitmap image. Right: A hemi light icon appears above a primitive cube
in Blender. The light illuminates anything below its umbrella-like half-sphere shape. The hemi light is one of the standard Blender light types.
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Photometric This light type is designed to be physically accurate by using data from real-world lights (Figure 3.23). Photometric lights reproduce light intensity over distance and light spread, which is the light pattern a specific light bulb makes when housed in a particular enclosure (e.g. wall sconce, flashlight housing, lamp housing, and so on). Photometric lights receive their data from imported IES (Illuminating Engineering Society) profile text files. The files are made available to the public by light bulb and light housing manufacturers. Photometric lights are useful when recreating real-world loca-tions or as part of an architectural design process.
Volume These lights are similar to environment lights in that they illuminate any surface within their volume shape (Figure 3.24). The most common volume shape is a sphere. Volume lights offer an alter-native to using light decay to control where the light’s illumination reaches within a scene. Note that volume lights and volumetric lighting are not strictly the same. Volumetric lighting allows light to be seen within a 3D volume. You can create volumetric lighting by activating light log, environmental fog, or environmental light scattering, which simulates participating media. These options may be available through a particular light type, such as a spot light, with a specialized shader, or through a renderer.
Renderer Variations Some renderers offer their own sets of lights. Although the lights often take the form of common light types (area lights, spot lights, and so on), they are designed to create more accurate lighting results. Some of these light types support PBR techniques. PBR is discussed in detail in Chapter 5.
Figure 3.23 Three side-by-side photomet-
ric lights using three different IES profiles
create three distinct light spreads. The
IES files carry data derived from specific
real-world light bulbs and housings.
Figure 3.24 Left: A volume light intersects a
primitive sphere and sits above a primitive plane.
Right: With the resulting render, only the part
of the sphere that intersects the volume light
receives illumination. The plane remains unlit
because it does not intersect the light.
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Chapter 3
3D Light Interaction with Shaders3D lighting is dependent on 3D surfaces. The surfaces are provided by 3D geometry that has been assigned to shaders. Shaders mathematically define surface qualities, which include the surface’s color and whether the surface is matte-like, glossy, reflective, refractive, smooth, and/or bumpy (Figure 3.25). When lighting, it’s im-portant to understand how the assigned shaders are functioning. In fact, it may be necessary to adjust shader properties to produce the best lighting results.
Any given 3D program provides a number of different shaders, each with different strengths, weaknesses, and different sets of properties. Brief descriptions of common shaders follow. Note that shaders are sometimes referred to as materials.
Lambert This shader type is simple, offering a diffuse color property (left side of Figure 3.26). Lam-bert shaders are designed to mimic matte surfaces, where light is scattered diffusely—that is, in a random fashion due to tiny surface imperfections. Real-world Lambertian surfaces include paper and cardboard. Note that Lambert shaders are unable to support reflectivity due to the lack of specularity. Lambert shaders are named after Johann Heinrich Lambert (1728-1777), who studied light diffusion. Oren-Nayer shaders are also designed for diffuse surfaces but increase the resulting accuracy and are ideal for creating powdery surfaces.
Figure 3.26 Left: Model assigned to Lambert shader. Middle: Model assigned to Phong shader. Right: Model assigned to
Blinn shader. You can adjust Phong and Blinn shaders so they are virtually identical. Note that the reflectivity for the Phong
and Blinn shaders has been set to 0.
Figure 3.25 Icons for shaders discussed in this section, as seen in Autodesk Maya.
63
Phong / Binn Phong shaders combine several basic surface properties, including diffuse color and specularity (middle of Figure 3.26). The shader creates specular highlights, which appear as bright “hot spots” that mimic the intense reflections of bright light sources. Ray tracing is not required to create the specular highlights, as they are only an approximation of specular reflectivity. Blinn (or Blinn-Phong) shaders build upon the Phong model with increased mathematical efficiency and their own variation of specular highlight controls (right side of Figure 3.26). Phong and Blinn shaders can emulate a wide range of real-world materials; however, they are not physically accurate. Phong shaders are named after Bùi Tường Phong and Blinn shaders are named after Jim Blinn, both 3D researchers and programmers.
Cook-Torrance This shader type increases the realism of specular highlights by adding a Rough-ness property that represents microfacets on a surface. Microfacets are tiny surface imperfections. If microfacets are aligned, a surface appears shiny. If the microfacets are randomly oriented, the surface appears diffuse and matte-like. The shader type is named after Robert L. Cook and Kenneth E. Torrance.
Fresnel This shader type employs more accurate reflections by taking into account the Fresnel effect. The effect occurs in the real world, whereby the strength of a reflection is dependent on the viewing angle (Figure 3.27). The effect is particularly evident with transparent surfaces. If the viewing angle is large, the reflection is strong. You can see this phenomena when looking across a lake (Figure 3.28). If the viewing angle is small, the reflection is weak. You can see this phenomena when looking down at the edge of the same lake. Where the reflection is weak, you can see the lake bottom due to light trans-mission and refraction through the water (see the next section for information on refractive indexes). Note that a reflected light ray shares the same angle between the surface normal as does the incom-ing, incident light ray (Figure 3.29). Hence, when reflections occur on smooth surfaces such as mirrors or calm water, the reflections are not distorted and do not change in scale. See Figure 3.34 in the next section for an example of a 3D Fresnel render.
Lighting in 3D
Figure 3.28 Fresnel reflections
appear on a calm lake.
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Reflective Surface
θ
Surface Normal
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the surface normal and a vector drawn from the viewer
to the surface.
64
A shader that supports Fresnel reflections is not necessarily named Fresnel. However, a shader that supports such reflections will carry several properties that determine if Fresnel reflections are off or on and what the reflectance strength is when the viewing angle is perpendicular to the surface normal (90 degree) and/or parallel to the surface normal (0 degrees). Fresnel shaders are useful for emulating transparent surfaces such as glass or water. This shader type is named after physicist Augustin-Jean Fresnel (1788-1827), whose mathematical work on light has become known as Fresnel equations.
Ward / BRDF A Ward shader uses BRDF (Bidirectional Reflectance Distribution Function) to determine how much light energy is reflected off a surface. In the real world, the amount of light energy reflected from a surface is equal to or less than the energy carried by the incident light ray (this is known as the conservation of energy). A Ward shader generally includes a Slope property that emulates microfac-ets and determines if the surface appears matte-like or shiny. The Slope property allows for extremely small and sharp-edged specular highlights. Note that BRDF creates its own form of view-dependent reflectivity, much like a Fresnel shader. BRDF and Fresnel properties may be included within the same shader, although they are generally not used together. The Ward shader is named after Gregory J. Ward. See Figure 3.34 in the next section for an example of a BRDF 3D render.
Anisotropic When the Ward shading method is included in a complex shader, it’s often the isotropic variation. As such, the rotation of the surface in reference to the camera does not change the shape of the specular highlight. However, when the Ward anisotropic variation is employed, the surface rotation changes the highlight shape. This shader type adds X and Y properties to control the orientation of the highlight. Anisotropic shaders can produce elongated highlights and are suitable for surfaces such as brushed metal, grooved plastic, hair, feathers, and rippled water (Figure 3.30).
Chapter 3
Reflective Surface
θr
Surface Normal Incident RayReflected Ray
θi
Figure 3.29 The angle between the arriving, incident
light ray and the surface normal is identical to the angle
between the surface normal and reflected light ray.
Figure 3.30 Left: Anisotropic specular highlights appear as light bands in dark hair. Right: A 3D render creates anisotropic highlights
appropriate for a grooved metal disc. Note that the highlights are perpendicular to the direction of hairs and grooves.
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Lighting in 3D
SSS (Sub-Surface Scattering) SSS shaders create translucence by diffusely scattering light through a surface. In contrast, transparency allows light to pass through a surface without scattering (although there is a change in light speed, which is discussed in the next section).You can see translucence when you place a light behind skin, soap, wax, plastic, and paper (Figure 3.31). SSS shaders replace the diffuse color component of a render with averaged surface values from a light map. A light map is a special bitmap texture that stores surface brightness information.
Monolithic and Layered Monolithic shaders combine a set of basic shader algorithms within a single shader structure. For example, the Arnold Ai Standard Surface shader utilizes Cook-Torrance, Ward anisotropic, and SSS shader functions (among others). The goal of a monolithic shader is to provide the maximum amount of control to produce physically-accurate shading results. A layered shader, such as the NVIDIA mental ray MILA, is monolithic but allows the user to pick and choose which shader functions are available; for example, the user can choose to ignore refractivity or select between direct and indirect (bounced) diffuse lighting contributions. Note that some 3D programs allow you to choose different shaders to define the diffuse color and specular highlight. For example, in Blender you can choose an Oren-Nayer, Fresnel, or Lambert shader to define the diffuse color and a Blinn, Phong, Cook-Torrance, or Ward isotropic shader to define the specular highlight.
Common Shader PropertiesDespite the wide array of available shaders, many shaders share common properties. These are described here.
Diffuse Color Sets the base color of the surface. The base color is the color of the surface without re-flections under white light. You can map this property with a bitmap texture to create color variations across the surface. The property controlling diffuse color is often named Color. However, some shaders carry a separate Diffuse property that controls the degree of diffuse light scattering, where some scattered light does not return to the camera or viewer. The lower the Diffuse value, the more light is randomly reflected away from the camera and the darker the surface appears. The higher the Diffuse value, the less light is randomly reflected away from the camera and the brighter the surface appears. Diffuse color is referred to as albedo with PBR systems; albedo does not include lighting information.
Ambient Color Determines the color of the surface when lit by ambient light but no direct light. In other words, this is the color of the surface that is in shadow. This property is usually black by default, which equates to ambient light with 0 intensity. However, you can change the color to non-black color to emulate ambient light arriving from all points in a scene.
Figure 3.31 Left: A rice paper screen is
translucent, allowing light to scatter
diffusely through its surface. A shadow of
a tree blocks some of the light. Right: A 3D
render of a soap bar uses a SSS shader. The
only light lies behind the geometry out of
view of the camera.Le
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Specularity / Glossiness / Metal Shaders that support specularity provide a set of specular properties that control the size, intensity, and color of the specular highlights or specular reflections. Alternatively, the shader may provide a glossiness set of properties. Glossiness defines the blurriness or sharpness of reflections based on the smoothness or roughness of the reflecting surface (Figure 3.32). Glossiness properties provide more realism than specular properties but are dependent on ray tracing. In addi-tion, some shaders provide a Metal or Metalness property that uses the diffuse color or a special metal color map to tint reflections—this simulates reflective qualities common to metallic surfaces.
Transparency Controls the opacity of the surface. In general, a value of 1.0 or a white color is 100 percent transparent and a value of 0 or a black color is 100 percent opaque. Transparency is necessary for transmission and refractivity but does not activate those functions.
Reflectivity This property sets the degree to which the surface reflects light. A high reflectivity value creates a bright reflection. For this property to function, the scene must be ray traced by the renderer. Note that PBR systems may use the term diffuse reflectivity to refer to scattered, refracted light, some of which re-emerges from the surface. As such, specular reflectivity refers to all reflections occurring when light reflects off a surface but does not penetrate it, whether the reflection is glossy or non-glossy.
Refractivity Controls light transmission for transparent and semi-transparent surfaces. The property, which is sometimes called refractions, is usually combined with a Refractive Index or IOR (Index Of Re-fraction) property. As discussed in Chapter 1, a refractive index is a numerical value that represents the change in speed of a light ray as the ray crosses an interface (boundary) between two materials (Figure 3.33). The materials may be air and water, air and glass, and so on. The change in light speed creates the illusion that the objects behind the transparent surface are distorted (Figures 3.34 and 3.35). The refractive index of a vacuum is 1.0, which indicates no change in speed. Air is close to 1.0 and is often rounded down to 1.0. Water has an index of 1.33 and glass has an index that varies between 1.2 and 1.4. Ray tracing is required for refractivity. For both refractivity and reflectivity, there are renderer prop-erties to control the number of times that light rays are permitted to reflect off and/or transmit/refract through surfaces. Note that a refractive index property is equally useful for opaque surfaces that use Fresnel reflections. In this case, the refractive index value affects the percentage of light energy reflect-ed back toward the camera or viewer.
Chapter 3
Figure 3.32 Left: A dark, reflective surface is given a high glossy value, creating a coherent reflection. Middle:
The same surface is given a medium glossy value, blurring the reflection. Right: The same surface is given a low
glossy value, making the reflected object unrecognizable.
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Lighting in 3D
Figure 3.33 When a light ray crosses a material interface
and is transmitted through the second material, the light
speed is altered and the ray is thus refracted.
Material Interface
θr
Surface Normal Incident RayReflected Ray
θi
Refracted Ray θt
Material 1
Material 2
Figure 3.35 Real-life reflections and refractions seen on a pair of wine glasses.
Note that the glass of the glasses and the liquid of the wine each has its own
unique refractive index. In reality, we only see transparent glass due to the
reflections and refractions.
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. Figure 3.34 Left: 3D render of spheres assigned to a reflective, refractive shader. The shader uses BRDF, allowing faint reflections of the blue sky to re-
main on the forward faces of the spheres. Right: The same shader is assigned but a Fresnel function is activated, preventing reflections from appearing
on the forward faces. Due to the spherical shapes and a refractive index value of 1.4, the blue sky is flipped upside-down in the refractions. In order to
produce semi-transparent cast shadows, you must use ray trace shadows or a specialized depth map shadow format that understands transparency.
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Chapter 3
Incandescence / Emissive Treats the surface as a light source. The illumination may be used to light other geometry if the function is supported by the renderer. For example, Iray, Chaos Group V-Ray, and Arnold renderers can use an emissive shader to light a scene (see Chapter 6).
Translucence Approximates sub-surface scattering but is not as computationally expensive as a SSS shader. In general, there are several properties that control the strength, focus, and virtual depth of the scattered light. A separate but related property is Backlighting, which assumes light has traveled through a surface from a side unseen by the camera to the side facing the camera. Backlighting creates the appearance of translucence but does not include additional controls to adjust the result.
Bump Mapping / Normal Mapping Create the illusion that a surface is rough or bumpy by per-turbing surface normals at the point of render (Figure 3.36). Bump mapping uses a scalar (grayscale) bitmap texture to determine the locations of peaks and valleys of the bump. Normal mapping uses a special normal map texture to do the same. (Normal maps are often generated by comparing a high-resolution model and low-resolution model and encoding the difference of surface vertex po-sitions as vector values in RGB.) For more information on texturing, see the sidebar at the end of this chapter.
Displacement Mapping / Parallax Mapping The goal of displacement mapping is similar to bump of normal mapping. However, displacement mapping distorts the surface at the time of render (Figure 3.37). Whereas a bump or normal map cannot affect the silhouette edge of an object, displacement mapping can change the shape of an object to a great degree. Displacement mapping uses a grayscale displacement or height map to determine how far to push or pull surface vertices. Parallax mapping, also known as offset mapping or virtual displacement mapping, is a more advanced form of bump and normal mapping that approximates the effect of displacement mapping without the cost of distorting geometry.
Note that some properties of shaders are intended to create special render passes to be used in 2D composit-ing programs. Render passes are discussed in Chapter 5.
Figure 3.36 Left: Raised letters are added to an otherwise smooth piece of 3D geometry with a bump map. Note that the letters react appropriately
to light direction and gain their own specular highlights and self-shadowing areas. Right: The square texture bitmap used as a bump map. Only the
white area of the letters appears as a bump. The location of the letters is based on the geometry’s UV layout, which controls how textures are applied
to the surface.
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“Look beneath the surface let not the several quality of a thing nor its worth escape thee.”—Marcus Aurelius Antoninus
Texture Overview
Textures are an important part of the 3D process. Textures, which are procedurally generated by the 3D software or imported as a bitmap, add color variation and detail to otherwise solid-color shaders. In addition, you can link textures to a wide variety of shader properties to lend even more complexity to a surface. Texturing, as a phrase, refers to the process of assigning shaders to geometry and adding texture maps to the shaders. Bitmap and map refer to a 2D digital image. Mapping refers to the process of linking maps to shader properties.
Many of the 3D models illustrated in this book have texture maps assigned to the color proper-ties of the assigned shaders. With the exception of bump maps, no other properties have been mapped. Although this limits the realism of the renders, it makes it easier to share the exercise files across a wide variety of 3D programs.
SID
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R
Figure 3.37 Left: A primitive polygon sphere is assigned to a shader with a bump map. The edges and
shadow are unaffected. Right: An identical sphere is assigned a shader with a displacement map, which
alters the geometry edges and affects the shadow.
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Chapter 4: Emulating SpecificLight Sources
Each light source, whether it’s natural or artificial, has unique properties. You can emulate each light source type by carefully choosing a 3D light or lights and selecting appropriate translations, rotations, intensities, colors, shadow types, and shadow qualities. This is equally true when lighting locations or lighting characters.
This chapter includes the following critical information:
• Recreating natural light sources, including the sun at different times of the day • Recreating artificial light sources, such as various forms of light bulbs • Applying lighting techniques to characters
“Light Painting, domes, on the banks of the Swan River Perth Western
Australia.“ by Gnangarra licensed via Creative Commons Attribution 2.5
Australia (CC BY 2.5 AU).
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Chapter 4
Emulating Natural Light SourcesIn previous chapters, we discussed the basic approach to lighting a 3D scene. We’ve also reviewed common 3D lights types, light properties, shadow variations, and shader categories. In this chapter, we’ll put that knowledge to use by replicating specific light sources within 3D scenes. We’ll begin by recreating natural light sources, including the sun at different times of day and candle flames.
Mid-day SunOur first task is to light the model of a modern house, as seen in Figure 4.1. The green camera icon indicates the rendering camera placement. This model is saved as house.fbx with the exercise files. The rendering camera is named renderCamera.
Source Models and Textures
The 3D models and textures used in this chapter are included with the book’s exercise material, which you can find at: www.routledge.com/9781138737570
The models are saved in a binary FBX format (2014/2015 version), which can be imported into a wide range of 3D programs. The textures are saved as PNG and JPEG bitmaps. The models and textures are licensed via Creative Commons. Licensing information for the models is included with the captions of the figures in this chapter. In addition, model-license.xls and tex-ture-license.xls are included with the exercise files. See the Introduction for more informa-tion.
If you choose to import an FBX file, you may need to relink, reload, or map the texture bitmaps through their corresponding shaders. If you are working with a 3D program that is unable to read the shader set-ups properly, you can still apply the lighting techniques with simple shaders that only provide a solid color. Alternatively, you can assign your own unique textures.
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Emulating Specific Light Sources
We’ll begin this exercise by answering the lighting questions introduced in Chapter 3:
What is the context of the lighting? This is a lighting exercise, so we are not concerned with matching any other project.
What is the location of the lighting? Exterior.
Does the location exist? The model is based on a real location but we are not concerned with match-ing it in a photorealistic way. However, we do want the lighting to look natural.
What is the time of day? Mid-day.
What is the time period? The present.
What are the properties of the light sources? This will be 2-point lighting:
A) Sun light as the key light. This will be hard lighting with clearly defined shadow edges.
B) Net reflected sun light serving as fill. The light bounces off the concrete, marble, and stucco surfaces, working its way inside the unlit interior.
Before we begin lighting, we should examine the model to see if there are any caveats—any unique features, constraints, or requirements that will affect our lighting. There is two features we will have to work with:
Reflective surfaces The house windows and top surface of the pool water are assigned to shaders that are 100 percent transparent as well as reflective. In addition, the pool surface is assigned to a shader that is refractive. As such, we will need to use a renderer that supports ray tracing. Without ray tracing, the windows and pool surface will be invisible.
Sky plane A large plane is placed in the background to serve as a sky. This is assigned to a self-illumi-nated shader that does not react to lights within the scene. You can also use an incandescent shader for this purpose. Without this plane, the empty area will render as black, which will make the lighting more difficult to judge.
A directional light is suitable for sun light and a key light. The directional light’s translation is not important. However, its rotation is. The light’s intensity should be high enough to make the exterior of the house appear bright without overexposing it so that the textures lose detail. We want to create shadows that are relatively short to indicate the sun’s high position. The shadows should be hard-edged. That said, there can be a slight softness as natural sun light is never as hard-edged as what’s produced by 3D lights. If you are using ray trace shadows, you can increase the light’s virtual radius by a small amount (the radius property name varies in each 3D program). If you are using depth map shadows, you can adjust the shadow edge. Because the mid-day sun produces light in the blue part of the visible spectrum, we can make the light color a desaturated blue. (Too much saturation and the scene will become heavily tinted.) We can adjust the directional light until it forms an aesthetic shadow pattern and appears a suitable brightness (Figure 4.2)
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When it comes to adding a second light as fill, there are several options:
Ambient light This is easy to add as the light reaches all parts of the scene equally. However, this will illuminate parts of the model that should remain fairly dark, such as the interior ceiling or bottoms of the bench and chairs.
Directional light or spot light You can aim either of these lights to emulate bounced fill light. How-ever, with these lights, you will have to experiment with the light rotation and translation to represent the net sum of all the light bouncing off walls and walkways.
Area light This light has the advantage of creating a soft wall of light from a particular direction. Much like directional lights and spot lights, you will have to experiment with the light rotation and transla-tion. In addition, the scale of the light has a dramatic effect on the resulting lighting.
Figure 4.2 Left: Approximate rotation of directional light, which is roughly –50, –24, –32 in XYZ. Right: Resulting render. Note the reflections on the
pool surface and glass windows and doors.
PBR Options
When lighting, there is always the option to use a PBR (Physically Based Rendering) lighting or rendering system. Such a system can automatically calculate bounced light, light decay, and soft shadows with a minimal effort by the lighter. However, such systems are not always practical due to lengthy rendering times. While PBR systems may produce more photorealistic results, photo-realistic results may not always be the end goal of a lighting project. Hence, it is advantageous to know how to light with simpler, non-physically-based systems. We’ll discuss PBR in more detail in Chapter 5.
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It’s not necessary to limit yourself to two 3D lights when recreating 2-point lighting. For example, you can use an area light and an ambient light to represent the net bounced fill light in the scene. That said, the more lights you have added to a scene, the more adjustments you will need to make to all the lights’ intensities to pro-duce a good result. For example, adding an area light and an ambient light to the house scene requires a lower intensity for the key directional light (Figure 4.3 and 4.4). With this example, the key directional has an intensity of 2.5, the fill area light has an intensity of 1.5, and the fill ambient light has an intensity of 0.1. This creates a lighting ratio of approximately 1.6:1. With this example, shadows are also activated for the area light, although its shadow is made extremely soft.
Figure 4.4 Final render using three lights to emulate 2-point sun-lit lighting.
Figure 4.3 Approximate translation and scale of the area light, which is pointing toward the house and rotated roughly 4, –74, 0 in
XYZ. The ambient light is not shown as it reaches all points in the scene equally.
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SunsetWe’ll use the house model once again to light a sunset scene. An outdoor sunset continues to use 2-point lighting; however, different light angles, light colors, light intensities, and shadow edge qualities will help create the dim, orange-red lighting scenario we normally associate with that time of day. We can re-use the previous lights. For example, in Figure 4.5 the key directional light is rotated so that it creates longer shadows (with the rotation roughly -41, 7, -65 in XYZ). The light color is changed to a pale orange and the light intensity is reduced. The directional light shadow continues to use ray trace shadows but the light’s radius is raised to 5 world units, creating a soft shadow that degrades along the edge. The area light, serving as fill, is left in the same position; its intensity is reduced and its color is changed to pale orange. The ambient light is deactivated; due to the lower angle of the directional light, the ambient light’s contribution is no longer needed.
Candle FlameThe next scene we’ll light features a table top with a candle, as seen in Figure 4.6. The green camera icon indi-cates the rendering camera placement. This model is saved as candle.fbx with the exercise files.
Figure 4.5 The mid-day lights are adjusted to create sunset lighting. The shader assigned to the sky plane is also set to orange.
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Figure 4.6 The candle model.
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We’ll begin this exercise by answering the lighting questions introduced in Chapter 3. We’ll skip to the most relevant questions:
What is the location of the lighting? Interior.
What is the time of day? Night. Aside from the candle, there are no apparent light sources.
What are the properties of the light sources? This will be 1-point lighting:
A) Candle light as a key.
Before we begin lighting, we should examine the model to see if there are any caveats:
Candle shader Candle wax is translucent, allowing light to scatter through its surface. Hence, the shader assigned to the candle supports translucency. The intensity, focus, and depth of the translucen-cy is set by the shader properties; that said, the intensity is also dependent on the light intensity.
Flame effect To create a visible candle flame, special geometry or an effects simulation is necessary. With this scene, a piece of flame geometry is animated deforming over time. The geometry is assigned to an incandescent shader to make it appear as if it is a light source. An effects simulation, such as one that uses particles, would produce more realistic results.
A candle flame is an omni-directional light source emanating from the small area in space. The flame itself un-dulates and changes intensity over time. This produces flickering and soft-edged shadows that change shape. We can use a single point light to create this light. For example, in Figure 4.7, a point light is placed above the candle wick. The light color is set to pale orange and depth map shadows are activated and given a soft edge. To create light falloff, light decay is activated. However, instead of using a more physically-accurate quadratic equation, a linear equation is used. This allows the candle light to reach the back wall while maintaining a fairly low intensity. (For more information on light decay and decay formulas, see Chapter 3.)
Figure 4.7 A point light emulates a candle flame. A soft-edge depth map shadow and a linear light decay further
recreate this type of natural light. The candle geometry is assigned to a translucent shader.
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In order to create a virtual flicker, the light intensity is animated randomly increasing and decreasing over time. In addition, you can animate the light icon moving a small, random distance in XYZ. This causes the shadows to shift over time (Figure 4.8).
Once again, it’s not necessary to limit the number of lights you are using to light a particular scene. With this example, a second, low-intensity ambient light is added. The ambient light contributes a small amount of brightness to areas of the frame in deep shadow, such as the base of the candle holder.
Diffuse Window Light
The next model we’ll light is an interior room, as seen in Figure 4.9. The green camera icon indicates the ren-dering camera placement. This model is saved as room.fbx with the exercise files. The rendering camera is named renderCamera.
Figure 4.8 Top: Frame 10 of a short animation. Bottom: Frame 20 of the same animation. Note the subtle
changes to the shape of the shadow and the intensity of the translucency on the candle.
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Here are answers to basic questions about the scene:
What is the location of the lighting? Interior.
What is the time of day? Daytime.
What are the properties of the light sources? This will be 2-point lighting:
A) Sun light scattering through an unseen window at the left side of frame serves as key.
B) Fill light in the form of sun light bounced off floors, walls, ceiling, and furniture.
Here is the caveat for the scene:
Reflectivity Several shaders include reflectivity, requiring a renderer that supports ray tracing.
Area lights are well-suited to recreate sun light scattering through a window. Although sun light is virtually parallel when reaching Earth and when unobstructed, a restriction such as a door or window causes the light to scatter. The exception is the occasion when light rays are able to penetrate the room with no obstructions along the way. We’ll assume that is not the case with this exercise. The window glass, window sills, curtains, and similar obstacles cause additional scattering. As an example, an area light is placed at the left side of the model and scaled to be roughly the size of a floor-to-ceiling window (Figure 4.10). Linear light decay is acti-vated. Once again, quadratic maybe more physically accurate, but the falloff can appear too rapid and drastic. Note that the use of light decay requires higher light intensity values than may otherwise be used. Ray trace shadows are activated. Due to the basic functionality of the area light, the shadows are soft-edged by default.
Figure 4.9 The room model.
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“If a window of opportunity appears, don’t pull down the shade.”—Thomas Peters
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Once again, there are several routes you can take to add a secondary fill light. You can add a different light for each “wall” of bounce light. For example, you can add one light for the right-hand wall, one light for the floor, one light for the ceiling, and so on. The lights might be area lights or directional lights. Alternatively, you can add an ambient light, which reaches all points within the scene equally. A third option requires the addition of one light that represents the average of all bounced light. As such, you must find a translation and rotation that can represent the general fill light that might be present. For example, in Figure 4.11 and 4.12, a second area light is placed at the right foreground corner of the room (behind the camera). The light is pointed toward the room and is given linear light decay, ray trace shadows, and a lower intensity.
Figure 4.10 Left: Approximate translation and scale of area light, which is rotated roughly 2, –78, –10 in XYZ. Right: The resulting render.
Figure 4.11 Approximate translation and scale of sec-
ond area light serving as fill. The light is rotated roughly
8,37, 0 in XYZ.
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Emulating Artificial Light SourcesArtificial light sources come in many different varieties due to the technology that provides them. There are different light bulbs, such as incandescent, fluorescent, halogen, neon, HID (High Intensity Discharge), and LED. There are innumerable artificial light housings and light arrangements. Nevertheless, you can follow the same basic 3D lighting steps when tackling a scene lit by artificial lights.
Table LampThe first artificial light source we’ll emulate is a common table lamp, as seen in Figure 4.13. The green camera icon indicates the rendering camera placement. This model is saved as lamp.fbx with the exercise files.
Figure 4.12 Final render after the addition of a second area light serving as fill. The darkest corners receive a small amount of illumination and are no
longer pure black.O
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Figure 4.13 The lamp model.
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Here are answers to basic questions about the scene:
What is the location of the lighting? Interior.
What is the time of day? Nighttime. The only visible light source is the table lamp.
What are the properties of the light sources? This will be 2-point lighting:
A) A light bulb mounted in the lamp serves as the key light. It escapes through the top and bottom of the lamp shade, forming two distinct pools of light.
B) Light scattering through the translucent shade provides fill light.
Here is the caveat for the 3D scene:
Incandescent shade The lamp shade is assigned to a shader that supports incandescence. Without incandescence, the shade would appear solid and the lamp’s illumination would appear dimmer. Alternatively and more accurately, you can use a shader that supports translucency or sub-surface scattering.
There are several options for placing and adjusting a key light:
Point light A point light is similar to a light bulb in that it is omni-directional. If shadows are activated, you can create shadow shapes that are appropriate for the lamp shade.
Mesh light If you use a renderer that supports custom lights based on user-selected geometry, you can create a light bulb shaped surface and have it illuminate the scene. However, mesh lights are com-putationally expensive to render.
Spot lights If you use two spot lights—one pointing up and one pointing down, you can quickly recreate the light pools created by a lamp shade. By using two lights, you will have greater control over their radius and orientation. In addition, the resulting shadows may be easier to refine and less render-intensive.
As seen in Figure 4.14, two spot lights are positioned within the lamp shade. The cone sizes are adjusted to glance the top and bottom openings of the shade.
The spot lights cast depth map shadows with a soft edge setting. Although depth map shadows are efficient, they may not create believable shadows at the bases of small objects, particularly when they are soft-edged. As seen in Figure 4.14, the shadows cast by the small bowl and plate are not well-defined. As an alternative, you can use ray trace shadows. In order to get a soft edge with such shadows, you must increase the light’s vir-tual radius (Figure 4.15). For example, when using spot lights in Autodesk Maya, you can raise the Light Radius property value. In Blender, you can raise the Soft Size value.
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To create fill light scattering through the lamp shade, we can use a point light with no shadows. For example, in Figure 4.16, a point light is placed in the center of the shade. The point light is given quadratic decay with a high intensity. To prevent pure black from appearing at the lamp base and at the edges of the frame, an am-bient light is also added with a low intensity. As a final step, each light is given a pale yellow color to emulate light bulbs that have a 2500 K to 2700 K color temperature, which is often found in households.
Figure 4.14 Left: Placement of two spot lights. Right: Resulting render. Depth map shadows with soft edges are used.
Figure 4.15 The bottom spot light’s shadow type is switched to ray trace with a large radius value. The resulting shadows form
better connections to the object bases.
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Neon Sign
We’ll move on to a unique form of light—the neon tube, as seen in Figure 4.17. The green camera icon indi-cates the rendering camera placement. This model is saved as neon.fbx with the exercise files. The render-ing camera is named renderCamera.
Selective Shadow Casting
Many 3D programs allow you to selectively choose what objects cast and receive shadows. In general, it’s desirable to have all surfaces in the scene cast shadows. However, in some situations, you can produce more aesthetic results by using this option. For example, with the lamp scene in this section, shadows were deactivated for the internal socket structure of the lamp model. This prevents odd-shaped shadows from appearing. Activating and deactivating shadows per surface may be less physically accurate but it can produce more attractive results.
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Figure 4.16 Final render with the addition of a point light placed in the center of the shade and a low-intensity fill light. The light colors are changed
to pale yellow to emulate common household light bulbs.
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Here are answers to basic questions about the scene:
What is the location of the lighting? Interior.
What is the time of day? Nighttime. The only visible light source is the neon tube.
What are the properties of the light sources? This will be 1-point lighting:
A) A twisted neon tube serves as the key light.
Here is the caveat for the 3D scene:
Incandescent tube The neon tube is assigned to a shader that carries a moderate amount of incan-descence. The incandescent color is red.
If you use a renderer that supports a custom mesh light, you can convert the neon tube geometry into a light source. However, it’s not always necessary to create physically-accurate lighting to generate aesthetic results. As a more efficient alternative, you can use an area light with a very soft shadow edge. For example, in Figure 4.18, an area light is placed close to the neon with a scale that’s slightly larger than the neon. Depth map shadows are activated and given an extremely soft edge. With depth map shadows, this requires a small map resolution and a large edge filter property value. The edge filter property has different names in different pro-grams, such as Filter Size in Maya, Sample Range in 3ds Max, and Softness in Blender. The light color is set to red.
One element that is lacking is a glow. Bright light sources often appear to be glowing, whether due to light scattering through participating media such as smoke or haze or by light scattering through the optical elements of a camera. Adding a glow as an effect is a common task for 2D digital compositing. In fact, most renders created for large animation projects are processed in a compositing program as a final step, either by the lighter or by a specialized team of compositors. Some 3D programs provide shaders or shader options that create a post-process glow (a glow that’s applied on top of a rendered frame). Figure 4.19 features one such glow.
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Christmas Lights
The next artificial lighting set-up we’ll work with is a string of Christmas lights, as seen in Figure 4.20. The green camera icon indicates the rendering camera placement. This model is saved as tree.fbx with the exercise files. The rendering camera is named renderCamera.
Figure 4.18 Approximate translation and scale of area light. Right: resulting render. The light is given a red color. The neon tube is assigned to a shader
with a moderate amount of red incandescence.
Figure 4.19 A post-process red glow is added courtesy of a shader.
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Here are answers to basic questions about the scene:
What is the location of the lighting? Interior.
What is the time of day? Nighttime. The only visible source of light is a string of Christmas lights.
What are the properties of the light sources? This will be 1-point lighting with multiple keys:
A) Numerous small bulbs serve as an array of key lights. Each bulb, on its own, is fairly dim.
Here is the caveat for the 3D scene:
No geometry There is no geometry to represent the string of Christmas lights. However, due to the stylized nature of the tree, this is not a limitation.
To create an individual Christmas light bulb, you have several options:
Point light This light type is similar to a small light bulb in that they are both omni-directional. How-ever, the light itself will not be visible in renders. You can limit the intensity of the light by using light decay.
Volume light This light type has a specific volume (generally spherical) and a specific scale that you can set. It has a natural decay due to the limits of the volume shape. With some renderers, you can make the volume of the shape visible by activating light fog, which simulates participating media.
Advanced area light Some renderers, such as Arnold and V-Ray, support an advanced form of area light that can be made into different shapes that include discs, rectangles, and volumetric spheres. In addition, you may have the option to make the light visible in the final render.
Figure 4.20 The Christmas tree model.
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Figure 4.21 uses a set of visible, sphere-shaped area lights. The lights use quadratic light decay and are given one of three colors. Despite the light decay, the combined light reaches the back walls. Because there is a large number of lights in the scene, depth map shadows are used with a small resolution and a soft edge quality.
Lighting a Character with Different Light SourcesCharacter lighting is a large portion of all 3D lighting. Hence, it’s important to emulate different light sources and make the light aesthetic when falling on a character. This applies to a wide range of characters, including photoreal, cartoon-like, human, alien, monster, and animal.
For example, we can use a cartoon-like model of a girl to emulate different natural and artificial light sources (Figure 4.22). Although the girl is not realistic, we can still apply realistic forms of lighting to help communi-cate the time of day and general location. We’ll begin with sun light. Here, 2-point lighting is suitable. You can place the key light to form Rembrandt, loop, butterfly, or split lighting. As demonstrated earlier, a directional light is appropriate for emulating the sun (and moon). Establishing the time of day is a matter of selecting an appropriate light rotation, light intensity, light color, and shadow edge quality (Figure 4.23, 4.24, and 4.25). The girl model is saved as girl.fbx with the exercise files. The rendering camera is named renderCamera. For additional examples of character lighting, see Chapter 6.
Figure 4.21 Two dozen area lights with spherical shapes and three different colors are placed throughout the
tree.
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“Light in Nature creates the movement of colors.” —Robert Delaunay
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Figure 4.22 The girl model.
Figure 4.23 Two directional lights are used for 2-point lighting. The high angle of the key and pale blue color suggests a time that is
late morning or early afternoon The lighting is a form of loop lighting that produces small shadow under the girl’s nose on the right
side of frame. The fill has lower intensity and produces no shadows. The lighting ratio is approximately 6:1.
Key
Fill
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Figure 4.24 To create a sunset/sunrise look, the key light is rotated parallel to the virtual ground, given an orange color, and
a lower intensity. In addition, the key light’s shadows are switched to depth maps with soft shadow edges. Sunset/sunrise
shadows tend to be softer due to the sun light scattering through the atmosphere and cloud cover. The fill light is rotated
to arrive from the opposite direction and given an orange color. This lighting is a form of split lighting with a low contrast
between the left and right side of the face. The lighting ratio is 4:1. Note that a more expansive 3D environment may require
adjustments to the key light; for example, a different rotation may be required to illuminate the ground as well as the girl.
KeyFill
Sunset / Sunrise
Figure 4.25 To create the look of night, as if the scene is lit by moon light, the key light is rotated to make it relatively
perpendicular to the virtual ground. The key is given a medium blue color, a lower intensity, and an extremely soft depth
map shadow. The fill light is rotated to arrive from the opposite direction. The fill also received a blue color and a lower
intensity. The Emit Specular option, a common property among 3D lights, is turned off for the fill light, preventing specular
highlights from forming on the fill side of the girl. Specular highlights are associated with intense light sources, which are
not present in this lighting scenario. (An alternative option would be to reduce the specularity of the assigned shaders). The
light placement mimics Rembrandt lighting, although the soft shadows prevent a distinct nose shadow from forming. The
lighting ratio is 4:1.
Key
Fill
Moon-lit Night
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Moon light is sun light bounced from the moon’s surface. Although a blue-ish color is sometimes associated with nighttime, human vision becomes less sensitive to color at night due to the shut down of color cones in the eye. Hence, night appears desaturated and somewhat gray if there is little light.
In contrast to sun lit scenes, you can generally recreate a fire-lit scene with point lights (Figure 4.26).
In contrast to natural light sources, artificial light sources have a wider range of properties due to the many variations of artificial light design and manufacture. Nevertheless, if you can derive the light’s scale, color, focus, and shadow type, you can find a way to emulate it in 3D. For example, Figures 4.27, 4.28, 4.29, and 4.30 recreate car headlights, flashlights, flood lights, taillights, traffic lights, neon signs, and smart phone screens.
Figure 4.26 To emulate illumination from a small fire, such as a fireplace fire, gas lamp, or a set of candles, three point lights are
placed low in the scene. Each light is given a different translation, a different intensity, and a different yellow-orange color. The lights
use depth map shadows with different degrees of edge softening so that the shadows they cast overlap in a random fashion. This is
1-point lighting with three key lights and no weaker fill light. A low light position is often used to create tension in horror films and
other psychological dramas, although it doesn’t match any particular style of portrait lighting. If this lighting was intended for ani-
mation, you can animate each light’s translation and intensity changing in a random fashion. All lights use a quadratic light decay.
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“Some of the best conversations I’ve had are sitting around a camp fire.” —Robyn Davidson
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To make the headlight or floodlight scene more realistic, you can replace the standard spot light with a pho-tometric light that has an IES file loaded. The IES file would ensure that a specific intensity and light spread appears within the light pool. IES files emulate specific light bulbs in specific bulb housings. For example, you can use an IES file for a particular type of LED flood light. For more information on IES files, see Chapter 3.
Figure 4.27 To recreate light cast by a car
headlight or a flashlight, a spot light is pointed
directly towards the girl’s face. The light is given
a large penumbra angle value. Shadows are set
to depth map with a soft edge. This is 1-point
lighting with no fill. This can be combined with
moon-lit night time lighting in order to avoid
the pure blacks from appearing outside the
spot’s light pool. This type of high-contrast, low
key lighting is similar to lighting used in the
film noir or horror genres. It’s also similar to
lighting used on stage for a dramatic effect to
isolate a single performer.
Figure 4.28 To recreate an overhead light, such
as a wall-mounted floodlight, you can reuse
the spot light employed as a car headlight and
place it above the girl pointing downwards.
However, with such an extreme angle, there
will be no light on the front of the girl’s face. As
a workaround, a second point light is added as a
fill light with no shadows. To prevent the point
light from brightening the spot light’s shadow,
you can use light decay or light linking (see the
next sidebar for linking information). To avoid
the intense specular spot on the girl’s head,
you can adjust the specularity of the shader
assigned to the girl’s body.
Headlight / Flashlight
Floodlight
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Light and Shadow Linking
Many 3D programs offer the ability to make or break links between surfaces, lights, and shadows. Hence, you can choose what surfaces a light illuminates and what surfaces a light ignores. You can also choose what surfaces receive shadows and/or cast shadows. This is a convenient means to achieve aesthetic lighting without being bound to physically accurate techniques such as light decay and light bounce.
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Figure 4.29 To recreate the red taillights of an automobile, four identical point lights are arranged horizontally as
if housed along the back end of the vehicle. They are given soft depth map shadows, red color, and quadratic light
decay. A similar lighting setup would work for an off-screen neon sign or traffic light.
Taillights /Neon Sign
Figure 4.30 To recreate the screen illumination of a
smart phone, an area light is scaled to the same size
as the phone. With a scale adjustment, you can use
area lights to emulate any screen, including tablets,
televisions, and monitors. To emulate the color of the
screen graphics, you can map a bitmap texture or
bitmap image sequence to the light color property.
Smart Phone
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Chapter 5: Working with PBR Systems
Although you can light a 3D scene with basic lights and shadows to create a render that looks realistic, there are advanced lighting and rendering systems that take the realism much further. These systems pay close attention to the physical realities of light and how it interacts with our environments.
This chapter includes the following critical information:
• Overview of scanline and ray trace rendering • Overview of PBR systems and their unique features • Introduction to render passes and AOVs
“An image rendered using path tracing, demonstrating notable features
of the technique.“ by Qutorial licensed via Creative Commons Attribu-
tion-ShareAlike 4.0 International (CC BY-SA 4.0).
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Choosing PBRIn this book, I use the terms PBR and Physically Based Rendering to refer to 3D lighting systems, 3D shaders, and 3D rendering systems that strive for physical accuracy in order to create renders that look photoreal or that approach photorealism. When you light a 3D scene, PBR may be an option. However, there are several considerations to take into account:
Is physical accuracy in your lighting necessary? If the scene you are lighting does not benefit from light bounce, color bleed, or accurate shadow decay, then it might not be necessary to use PBR. This decision may be based on aesthetic criteria alone—for example, if the lighting project is stylistic, then it might not require excessive realism.
Can you achieve a realistic look without a PBR system? It’s possible to use non-PBR shaders, lights, and rendering systems to light a scene and produce a render that looks fairly realistic. Such a set up may never achieve the degree of realism of a PBR render, but it may be aesthetically suitable for some projects. (Note that the 3D scenes featured in earlier chapters did not employ PBR.)
Does your lighting schedule allow you enough time to use PBR? In general, PBR systems take more time to set up, adjust, and render than non-PBR systems.
Note that rendering systems, as a term, refers to a specific approach to rendering that uses particular algo-rithms. An algorithm is a set of rules followed during problem-solving operations. Renderers refer to specific rendering systems provided by software companies.
Review of Common Rendering SystemsBefore discussing PBR in more detail, it pays to be familiar with two of the most common rendering systems: scanline and ray tracing. Note that all the rendering systems are dependent on rasterization, whereby 2D shapes are converted to raster images, which are composed of rows of pixels (scanlines). With a 3D program, 3D polygonal shapes are converted to 2D via the view plane of the 3D camera.
ScanlineA scanline rendering system works on a row-by-row basis. For each scanline, the system follows these basic steps:
1. Identify intersections between polygon edges and the current scanline (Figure 5.1).2. Sort the intersections along the scanline from left to right.3. Fill in all pixels between pairs of intersections.
x
yFigure 5.1 A simplified representation of a
scanline rendering system. A scanline is shown
in red. A polygon shape, flattened into 2D by
the camera’s view plane, is colored gray. Edge
intersections are indicated with white dots. Filled
in pixels are drawn as yellow dots.
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Scanline rendering systems determine the color of the fill area by taking into account the properties of the shader assigned to the polygon and any present lights and shadows. Some 3D programs offer a scanline renderer as an option. For example, Autodesk Maya, Autodesk 3ds Max, and Blender include optional scanline renderers. Scanline functions may be included as a base component of advanced renderers. For example, you can force mental ray to scanline render and forgo ray tracing. A scanline rendering system is very efficient. However, the systems have the following limitations:
• No reflections • No transmissions / refractions • Creates approximated specular highlights instead of specular reflections
For example, in Figure 5.2, a transparent surface is rendered with a scanline renderer but appears like thin plastic due to the lack of proper reflections or refractions.
Ray Tracing
As discussed in Chapter 3, ray tracing rendering systems trace rays through a scene (Figure 5.3). The rays reflect off the surfaces, transmit through surfaces, or are absorbed by the surfaces (the ray is killed off). Ray tracing systems are able to offer the following:
• Reflections (see Figure 5.4) • Transmissions / refractions • Ray trace shadows (with transparency) • Absorption (light rays have a limited number of bounces)
These features, in and of themselves, do not create a PBR render. However, ray tracing is often a critical compo-nent of PBR rendering systems. Ray tracing systems may require a great deal of processor time due to the po-tentially high number of light rays and ray/surface intersections. As such, the systems generally offer controls for limiting the number of times an individual ray is permitted to reflect or transmit.
Figure 5.2 Left: An ornate bottle is rendered with a
scanline renderer. Right: The same bottle is given 100
percent transparency through the assigned Blinn shader.
The resulting bottle appears like thin plastic due to the
lack of reflections or refractions. Note that the depth map
shadow also fails to take into account the transparency.
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Overview of PBR SystemsIn general, the physical accuracy of a PBR system is dependent on the following calculations:
• Diffusion (Including microfacet scattering) • Reflectivity (including Fresnel reflectivity and metallic specularity) • Transmission / refraction (including translucency) • BRDF (including conservation of energy)
Figure 5.3 A simplified representation of ray trace rendering. The brightness of a surface point is determined by comparing the vector between the
camera and surface point to the vector between the surface point and the light.
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Figure 5.4 Left: Bottle rendered with a ray trace renderer
and ray trace shadows, allowing for reflections, refractions,
and semitransparent shadows. Right: Same bottle with
75 percent transparency, allowing the purple diffuse color
to show. Note that the specular highlights generated
by the Blinn shader are only approximations of specular
reflections of light sources.
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Here are a few things to keep in mind when it comes to PBR shaders, PBR lighting systems, and PBR rendering systems/renderers:
• Linear Calculations For a PBR renderer to function in a physically accurate way, it must operate in a lin-ear color space (a color space with no gamma correction). As such, texture bitmaps with sRGB color space must be converted to linear color space. If color space management tools are provided by a 3D program, there will be an opportunity to interpret the color space of imported bitmaps. See Chapter 3 for more information on linear color space and color space management.
• Shader Properties A PBR shader may support all of the properties listed at the start of this section. PBR shaders are often used by video game engines, requiring the use of specially prepared PBR texture bit-maps. The maps may cover such properties as albedo (diffuse color without lighting), metalness (metallic specularity), glossiness/roughness (degree of diffusion for reflections), and AO (Ambient Occlusion)/micro-occlusions (light absorption in nooks and crannies). One hallmark of a PBR shader is the ability to create specular reflections of light sources. For example, in Figure 5.5, a PBR shader is assigned to the bottle and ground plane. Note that the shaders discussed here are sometimes said to use PBS (Physically Based Shading).
• Lighting Requirements PBR lighting systems may not require PBR shaders to function. As long as the shaders have basic properties such as diffuse color and reflectivity, the lighting systems will generally work (although some shader functions, like bump mapping, may be ignored). That said, PBR shaders will provide more accurate results for PBR lighting and rendering systems.
• Renderer Requirements PBR rendering systems may not require PBR shaders or PBR-based lights to function. That said, PBR shaders and PBR-based lights will provide more accurate results. For example, area lights are more physically accurate than 0-width point lights or non-positional ambient lights.
• Light Variations Some PBR renderers provide their own light variations, such as specialized area lights or spot lights. In general, these are not required to make the PBR setup function; however, such lights often include additional properties to increase the accuracy of the resulting PBR render.
Key
Fill
Figure 5.5 The bottle and ground plane are assigned
to PBR shaders. The specular highlights become
more accurate specular reflections of the lights in
the scene. Even though the point lights do not have
a specific width in world space, both non-PBR and
PBR shaders recognize the different intensities of
the lights when calculating the specular highlights/
specular reflections.
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Microfacets are tiny surface imperfections. When randomly oriented, microfacets create diffuse, matte-like surfaces that create non-glossy reflections. When oriented in the same directions, microfacets create glossy, coherent, mirror-like reflections. Fresnel reflectivity alters the strength of the reflection based on the view-ing angle. Metallic specularity bases the color of the specular reflection on the diffuse color. Non-metallic specularity bases the specular reflection color or the color of the incoming light ray. BRDF undertakes energy conservation by ensuring that the light energy reflected off a surface is equal to or less than the energy carried by the incident light ray. For more detail on these shader properties, see the sections “3D Light Interaction with Shaders” and “Common Shader Properties” in Chapter 3.
Review of Common PBR Systems
In this section, we’ll review common rendering and lighting systems that use PBR. This is by no means an ex-haustive list, but it does include systems that are commonly used. Each system has strengths and weaknesses, which are discussed here.
GI
GI (Global Illumination), as a term, has come to refer to any rendering system that simulates light bounce (more accurately known as indirect illumination, intersurface reflections, or secondary diffuse illumina-tion). There are several forms of GI that are available:
Photon mapping This form of GI emits virtual photons from lights and traces the photons as they bounce through the scene. Based on shader qualities, photons reflect off surfaces, transmit through surfaces, or are absorbed (killed off). Photon mapping follows BRDF by altering the energies of reflect-ed and transmitted photons. The energies are stored as red, green, and blue color values; hence, the resulting secondary diffuse illumination takes on the color of encountered surfaces and color bleed occurs. Secondary surface intersections and photon energies are stored in special photon maps. The maps are combined with more traditional scanline and ray trace renderers to create the final image. Photon mapping can be time-intensive due to the large number of photons that need to be traced through the scene. Photon mapping may also suffer from a graininess as the photon intersections must be averaged and each intersection may cover a fairly small area in world space (although the radius of photon intersections is generally adjustable). Hence, photon mapping is often combined with final gather. A simple example of photon mapping is demonstrated by Figure 5.6.
As a more complex example of photon mapping, we can return to the interior model we lit in Chapter 4. Instead of using two area lights, we can employ a single area light placed within the window area (Figure 5.7). All of the secondary diffuse illumination comes courtesy of the photon mapping.
Photon mapping is often used to generate caustics, which are focused specular highlights created by reflection or refraction. Caustics are often seen when light refracts through or reflects off glass, crystal, water, or shiny metal (Figure 5.8).
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“A rainbow is the product of physics working for your appreciation of beauty.” —Kyle Hill
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Figure 5.6 Left: A cyan plane hovers over a gray plane, lit by a point light. Middle: GI with photon mapping is activated. The cyan dots on the lower
plane are produced by photon intersections. The photons are generated by the point light and bounce off the surfaces in the scene. The diffuse color of
the surfaces the photons bounce off affects the photon color and intensity. The photon count, in this case, is too low and the photon intersections do
not blend smoothly. Right: The photon count is increased and the radius of the photon intersections is adjusted until the photon contribution blends
smoothly, forming cyan light bounce on the gray plane.
Figure 5.7 The interior room is rendered with photon mapping. A single area light, placed just beyond the left side of frame, is set to emit a total of
75,000 photons. In general, the higher the photon count, the more accurate the render but the longer the render times.
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Final gather You can use this GI system, also known as final gathering, by itself or in conjunction with another GI system, such as photon mapping. Final gather calculates light contribution by creat-ing final gather points where a camera view ray (also known as an eye ray) intersects a surface. The final gather point sends out secondary final gather rays in a hemispherical cloud (Figure 5.9). If the final gather rays encounter other surfaces, then the light intensities of the encountered surfaces are averaged with the intensity of the original intersection point. Much like ray tracing, final gather offers a means to limit the number of bounces a secondary ray is permitted. It’s also possible to limit the dis-tance the final gather rays travel through the scene. When compared to photon mapping, final gather tends to produce smoother results with less set up time and render time. However, the light bleed created by final gather tends to be more subtle than the bleed produced by photon mapping (Figure 5.10). Final gather is provided by renderers such as mental ray and is available in programs that include Maya, 3ds Max, AutoCAD, and Unity.
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Figure 5.8 Bright white caustic rings created with photon mapping and final gather.
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Figure 5.9 A simplified representation of the final gather process. The cyan dot represents potential color bleed.
Gray plane
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Camera eye rays
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Radiosity This type of GI calculates the intensity (brightness) of all surfaces in the 3D scene. The system does this by determining the amount of light reflected off each surface and how much of that light reaches every other surface (Figure 5.11). The results are stored by each unit of each surface, where each surface is broken into smaller units (sometimes called patches or elements, these do not necessarily follow the polygon face layout). The radiosity information is combined with the output of other render systems, such as ray tracing (Figure 5.12). Radiosity is view-independent and not reliant on a particular camera setup. However, conventional radiosity systems are unable to take into account specular reflectivity or transparency. In addition, the system is dependent on the number of units that the surfaces have been divided into and can suffer from graininess of poorly-defined shadow areas. However, recent developments of radiosity systems have optimized the process, making radiosity more viable. Programs such as 3ds Max and renderers such as Pixar RenderMan continue to support radiosity.
Point cloud This form of GI approximates light bounce by creating a point cloud out of all the geometry in the scene. The point cloud simplifies the scene by only including a limited number of micropolygons. Each micropolygon is approximated with a disc. The system tests for disc intersections to determine if there are intersurface reflections. Hence, ray tracing is not needed to determine those reflections. Point cloud GI is currently available with RenderMan and 3Delight renderers.
Working with PBR Systems
Figure 5.11 A simplified representation of the radios-
ity process. The dots represent light bounce.
Figure 5.10 The cyan plane is rendered with final gather.
Compare this to the photon mapping render in Figure 5.6
earlier in this section.
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Irradiance cache Another GI approximation that uses a sparse representation of surfaces visible to the camera to reduce the number of surface intersections necessary to calculate light bounce. The system assumes that the secondary illumination changes gradually over flat surfaces and that those surfaces require fewer GI calculations. Irradiance caches are available to such 3D programs as Cinema 4D and 3D renderers such as Redshift. Irradiance, in this case, refers to the amount of light energy a surface receives.
Path tracing / Monte Carlo ray tracing This form of ray tracing is considered the most physically accurate 3D rendering method at the time of writing. It is able to generate soft shadows, depth of field, motion blur, caustics, indirect illumination, and ambient occlusion without specialized shaders or post-processing steps. (Ambient occlusion calculates how any given point on a surface is exposed to ambient light.) As such, the use of path tracing supplants the need to employ GI systems such as final gather or photon mapping. The opening figure for this chapter was created with path tracing. In Figure 5.13, the room model is rendered with path tracing. The location of a single area light is indicated by Figure 5.14. As an additional example, the lamp scene first seen in Chapter 4 is revised with a path tracing renderer (Figure 5.15). The point light serving as fill is deleted and the two spot lights are left in their original positions. The spot light decays are set to linear and the light intensities are increased. The shadows are switched from standard ray trace to path-tracing supported shadows provided by the renderer.
Path tracing is built on the following principles:
1) In an indoor setting, all surfaces contribute illumination to all other surfaces.2) Light emitted from a light source and reflected from a surface is considered the same.3) Reflected light scatters in a way related to the incident angle of the arriving illumination.
Along with these principles is the assumption that “everything is shiny”—that is, all surfaces offer some degree of specular reflectivity and that no surface is 100 percent diffuse. As such, path tracing renderers do not rely on the reflectivity properties of non-PBR shaders. Instead, path tracing uses specular properties and creates specular reflections that accurately take into account the size, shape, and intensity of light sources.
These principles place some limitations on path tracing. For example, path tracing may not produce accurate subsurface scattering or incandescence. However, recent iterations of path tracing renderers have overcome many of the limitations. Path tracing serves as the core for the Arnold, Octane Render, Blender Cycles, and Corona renderers.
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Figure 5.12 Left: A render without radiosity. Right: A render with radiosity. Note the color bleed on the
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Figure 5.13 The interior room is rendered with a path tracing renderer. With path tracing, a single area light is required with no need of
additional fill lights. Note that the specular reflections, seen on the edge of the table and on the face of the vase, reveal the rectangular
shape of the area light. The light is set to cast shadows. In general, path tracing takes significantly more time to render than a standard ray
tracing renderer.
Figure 5.14 Approximate location of the key area light.
Additional walls and a ceiling are added to present additional
surfaces for light bounce. A vertical opening is left as a virtual
window for the light to pass through.
10101055“Color is my day-long obsession, joy and torment.” —Claude Monet
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IBL
IBL (Image-Based Lighting) is a 3D lighting system that uses a bitmap image to determine light intensity and color with the aid of a spherical projection (see Figure 3.22 in Chapter 3 of an example of the projection sphere). Because IBL relies on an image to determine lighting information, it’s often used for visual effects, architectural visualization, and other areas where it’s necessary to replicate a real-world location accurately. In fact, the images are usually sourced from digital photos of real locations. As such, photos used for IBL are often HDR (High-Dynamic Range). HDR photos combine multiple exposures within a single image with a high bit-depth, floating-point accuracy to ensure that all parts of the image are properly exposed. LDR (Low-Dynamic Range) images, such as an 8-bit PNG or Targa, are unable to store such large value ranges. Nevertheless, you can use an LDR image with IBL. For example, in Figure 5.16, an IBL setup is used to light the bottle and ground plane. Note that the image mapped to the IBL sphere appears in the background unless you adjust the IBL sphere visibility. The IBL image also appears in reflections.
Figure 5.15 The lamp scene is rendered with path tracing. A fill light is not necessary. Note the more accurate specular reflections in the lamp base
and on the various objects on the table. Also note the shadow decay over distance; where the shadow is distant from the shadow-casting object, it is
soft.
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Because the IBL projection is spherical, it requires an image with a special mapping. Equirectangular (also known as spherical or lat/long) mappings are common as 360 virtual reality cameras are able to produce photos with that mapping (Figure 5.17). However, IBL systems may also accept probe/angular style mappings (which appear like a reflection in chrome ball) or cubic crosses (where six views are unfolded into a cross-like pattern). The IBL sphere essentially shoots directional light rays from the sphere surface to the center of the sphere; the light color and relative intensity of each ray is taken from the nearest pixel of the mapped image.
Working with PBR Systems
Figure 5.16 Left: The bottle and ground plane are assigned to a non-reflective shader. The light color,
light intensity, and soft, overlapping shadows are generated by an IBL system using the image featured
in Figure 5.17. Right: The same bottle is assigned to a reflective shader. The IBL system provides the
reflections.
Figure 5.17 An equirectangular-mapped photo of a back yard from the view of an iron bench. Although this is an LDR image, it was
used to light the model in Figure 5.16. This image is included as 360casa.png in the Textures folder included with the exercise files.
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Sky Systems
Some 3D programs and 3D renderers provide a complete sky lighting system that emulates outdoor, sun-lit lighting. With these systems, the lighter is able to select the angle of the sun to mimic a particular time of day, choose a sun intensity, and set the sun color. The color of the empty 3D space is altered to match the sun color and thus create a sky. To add light bounce, you can combine the sky system with other GI systems. For example, Figure 5.18 features renders created with mental ray’s Physical Sun & Sky system in combination with final gather. As for other programs and renderers, 3ds Max includes Sunlight and Daylight lighting systems. The Arnold renderer offers a sky shader. Next Limit Technologies Maxwell Render, Glare Technologies Indigo, and V-Ray renderers offer their own sun and sky systems.
Figure 5.18 Top: Building lit with mental ray’s Physical Sun & Sky system. The direction of the virtual sun is indicated by the
arrows. Bottom: Same system with the lower sun angle and a sun color shifted towards red. The light bounce is provided by
a final gather.
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Overview of Advanced 3D RenderersThe following list highlights advanced 3D renderers that support various PBR functions. This is by no means a complete list. Advances in 3D rendering occur fairly swiftly, so this list will no doubt evolve over the years following the book’s publication. These renderers are available as plug-ins for a wide range of popular 3D programs.
3Delight (www.3delight.com) Supports path tracing and non-tracing rendering tech-niques and is based on the RenderMan rendering standard.
Arnold (Solid Angle, www.solidangle.com) Uses path tracing while supporting fur, hair, SSS, volumetric effects, custom channel render passes, and geometry instancing.
Corona (Render Legion s.r.o., corona-renderer.com) Uses path tracing, but supports “reality hacks” to override PBR functions and make the renderer more efficient.
Indigo (Glare Technologies, www.indigorenderer.com) Supports SSS, volumetric ef-fects, photometric lights, and physically-based cameras. Is able to operate with spectral color values (single wavelength color values), as opposed to RGB.
Iray (NVIDIA, www.nvidia.com ) A GI system that supports PBR lights, PBR shaders, SSS, volumetric effects, and virtual reality mapping and rendering formats. Keyshot (Luxion, www.keyshot.com) Serves as a real-timer renderer with support of rela-time ray tracing, PBR lights, and PBR shaders.
mental ray (NVIDIA, wwww.nvidia.com) A renderer with a long history and support for photon tracing, final gather, and IBL. Includes a large library of PBR lights and PBR shaders. As of November 2017, NVIDIA has announced that it is retiring mental ray in favor of new renderers, such as Iray.
Lumion (Act-3D, lumion3d.com) Designed for architectural visualization, places a prece-dence on PBR shaders that can render accurate building materials.
Maxwell Render (Next Limit Technologies, www.maxwellrender.com) Designed for architectural visualization and industrial design. Uses path tracing techniques and supports photometric lights, HDR workflow, hair, volumetric effects, and physically-based cameras.
Redshift (Redshift Rendering Technologies, www.redshift3d.com) Supports various GI techniques, including point cloud and irradiance maps, hair, PBR shaders, mesh lights, IBL, virtual reality formats, custom channel render passes, and physically-based cameras.
RenderMan (Pixar, renderman.pixar.com) RenderMan was developed by Pixar over 25 years ago but has been modernized with path tracing techniques.
V-Ray (Chaos Group, www.chaosgroup.com) Offers various hybrid GI systems, IBL, PBR lights, PBR shaders, volumetric effects, fur, hair, and virtual reality formats. V-Ray is demon-strated in the case studies at the end of this book.
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Unbiased vs. Biased Rendering
3D renderers are sometimes referred to as biased or unbiased. Theoretically, unbiased renderers do not take any shortcuts when calculating a render. For example, if ray tracing, an unbiased renderer would let every ray bounce until it has bounced out of the scene or has been completely absorbed. In contrast, a biased renderer takes shortcuts or uses approximations to save render time but still produces a quality render. A biased renderer would allow you to limit the number of times a ray can reflect or refract. An unbiased renderer is more precise than an unbiased one. However, both biased and unbiased renderers are capable of producing a render that appears physically accurate.
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An Introduction to Render Passes / AOVsWhen it comes time to render a 3D scene, one option is to break the render into render passes. A render pass breaks a single shot into multiple renders with separate objects or separate shading qualities. The passes are then recombined in a 2D compositing program. The recombination may fall to the lighter or to a specialized compositing team or department. The use of render passes is common for visual effects and feature animation work. Although working with render passes is not mandatory for successful 3D lighting, it pays to be familiar with the types of passes that are rendered. AOVs are a subset of render passes. AOV stands for Arbitrary Out-put Variable, where the Arbitrary refers to custom channels that are used above and beyond standard RGBA (Red Green Blue Alpha). AOVs separate and output specific shading qualities but don’t necessarily separate objects and don’t require multiple renders. For example, an AOV may render specular reflections in a custom channel beside the standard RGBA channels. Another term for a render pass is multi-pass. AOVs may have program-specific names such as render outputs or render elements.
Working with render passes or AOVs can be more efficient than rendering out a standard beauty pass (the default render produced by the renderer with all the shading qualities present). Here are a few reasons why:
• Individual renders are faster because only a portion of the objects or surface qualities are included with each render pass.
• Render passes allow you to re-render individual objects or surface qualities without forcing you to re-ren-der the entire frame with all its objects and surface qualities.
• If shading qualities are split into different render passes or separated into different AOVs, you can adjust them individually in a 2D compositing program. For example, if the specular reflections are rendered sep-arately from the diffuse color, you can adjust the brightness of the specular reflection in the compositing program without returning to the 3D program.
Descriptions of common render passes and AOVs that isolate shading qualities follow. 3D renderers generally give you the option to set up, manage, and render a 3D scene as passes or AOVs.
Diffuse Includes diffuse color but does not include specularity or reflectivity (left side of Figure 5.19). Diffuse may also lack cast shadows. Some renderers differentiate between direct diffuse and indirect diffuse passes.
Albedo Captures the surface color but does not include lighting, specularity, or self-shadowing infor-mation.
Specular / Glossy Isolates specular highlights (right side of Figure 5.19).
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Reflection / Refraction Isolates reflections or refractions.
Shadow Isolates cast shadows (left side of Figure 5.20). Shadow passes may be stored in RGB or in the alpha channel.
When diffuse, specular, and shadow passes are recombined, they are equivalent to original beauty pass (right side of Figure 5.20). Some render passes, known as utility passes, are designed for specialized 2D compositing tasks and are not intended to be used as-is:
Depth Also known as depth buffer or Z-buffer, this pass encodes the distance objects are from the camera (left side of Figure 5.21). You can use this pass in a compositing program to simulate depth effects such as depth-of-field or atmospheric fog. The result is similar to the depth maps created for shadow-casting lights.
AO (Ambient Occlusion) This pass captures the soft, subtle shadows that form in small cracks, crev-ices, and folds (right side of Figure 5.21). This type of shadowing is missed by standard depth map and ray trace shadows.
Figure 5.19 Left: Diffuse pass without cast shadows. Right: Specular pass. The assigned shader is a Blinn.
Figure 5.20 Left: Shadow pass. Right: Resulting recombination of diffuse, specular, and shadow passes.
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Matte Also known as a holdout pass, this type renders the objects in silhouette. This pass is used as a cutout matte in compositing programs (left side of Figure 5.22).
Normal Encodes the surface normal vectors in RGB (right side of Figure 5.23). This pass is useful for creating mattes or applying effects in certain areas of a render, such as the sides of objects not facing the camera. A curavture or pointiness render pass encodes the relative curvature of the assigned sur-face and is also useful for applying effects in particular areas, such as concave parts of the geometry.A position render pass is similar to a normal pass in that it encodes the XYZ positions of rendered points.
Motion Blur Captures the vectors of moving objects and encodes the information in the first two channels of RGB. This pass allows you to create motion blur streaks as part of the composite (as op-posed to the 3D render).
Figure 5.21 Left: Depth pass. Right: AO pass.
Figure 5.22 Left: Matte pass. Right: Normal pass.
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Lighting Render Passes
Through various means, it’s possible to break 3D lighting into different render passes. This allows the light colors, intensities, and shadows to be adjusted during the compositing phase. One approach to making a lighting render pass is to assign each light to a different pass with any geometry that requires illumination. A more practical approach requires the use of a Raw Lighting render pass, wherein direct illumination is encoded as a grayscale render that can be used as a matte during compositing; within the matted area of a beauty render, you can apply color correction effects to adjust the brightness, contrast, color balance, and so on.
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“Sometimes I’ll use four or five different photo apps on one photo just to get it where I want it to be.” —Tyra Banks
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Chapter 6: ReproducingLocations and LightingCharacters
Each location in the real world has unique properties which affect your lighting approach in 3D. This becomes more complicated when a character must also be lit. Once again, lighting in each situation can be made more smooth by proper planning.
This chapter includes the following critical information:
• Choosing between multiple light options for the same scene • Determining when to use PBR lighting systems • Designing lighting for characters and locations
Photo copyright Antonino Ruggeri / 123RF Stock Photo.hoto.
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Lighting Locations and CharactersWhen it comes to lighting, two of the most common subjects are locations and characters. Locations may con-sist of exteriors or interiors. Characters may range from cartoon-like to photoreal. With this chapter, we’ll have a chance to light those subjects using the techniques discussed in earlier chapters.
Reproducing Lighting at Specific LocationsIn this section, we’ll reproduce the lighting specific to real-world locations. This may appear similar to Chapter 4. However, we are not trying to emulate a specific light type with each example. Instead, we are trying to reproduce whatever lighting exists at the location. Nevertheless, we can use the techniques discussed in the previous chapters to determine what light sources exist, what 3D lights type we can use to replicate the real lights, and what, if any, PBR lighting systems or renderers we might use.
Location #1: Elevator Landing
For the first location, we’ll reproduce an elevator landing (Figure 6.1).
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As a first step, we’ll ask basic questions about the location:
What is the location of the lighting? Interior with a large opening off to frame right.
What is the time of day? Daytime, based on the overall light quality.
What are the properties of the light sources? This will be 2-point lighting:
A) Sun light as a key, arriving from frame right.
B) The net sum of bounced sun light acting as fill. The light reflects off the concrete floor, the red wall, and other walls unseen behind the camera and to the left of frame.
The next step is to determine what 3D lights to use within the 3D program and if any specialized PBR light-ing or rendering systems are to be used. A 3D mock-up of the scene is illustrated by Figure 6.2. Materials are assigned with textures derived from the photograph. This 3D scene is included with the exercise files as landing.fbx. The rendering camera is named renderCamera. The textures are also included in the Textures folder. (See the Introduction for more detail on the available files.) The 3D model is not an exact reproduction of the location but it should serve to demonstrate lighting approaches.
There are two lights that may make suitable key lights: directional and area. Either light is able to emulate sun light. However, due to the directional light’s lack of true position and scale, it does not work well as a portal light. A portal light is one that is designed to pass through an opening, such as a window or doorway. With this scene, the sun light has a limited area with which to pass through to the landing. Hence, the area light’s position and scale transform options makes it advantageous. You can place the area light on the right side of the frame just out of view. Determining the best translation, rotation, scale, intensity, and light color requires test rendering and adjustment until the results match the photo in a satisfactory way. You can derive clues for the light’s translation and rotation by examining shadows in the photograph. Figure 6.3 points out shadow an-gles. At the same time, you can note what areas of the floor and walls are the brightest and therefore closer to the light source. With these clues, we can determine that the shadow edges should remain fairly sharp. Hence, the area light scale should be relatively small (Figure 6.4) (The larger the area light, the softer the shadow edg-es.) Because the light intensity varies from the frame right to frame left side of the photo, we can also activate light decay. In this case, quadratic works well, although it requires a high light intensity value. (Note that the required light intensity is partially dependent on the scale of the model, with a large-scale model requiring higher intensity values.)
Figure 6.2 3D recreation of landing. Walls
and a ceiling have been added off-screen to
facilitate light bounce and reflections.
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Depth map or ray trace shadows can produce soft shadows, although ray trace shadows allow the shadow edge to change quality over distance (Figure 6.5). Selecting a ray tracing render also allows for reflections to appear in the metal elevator doors. However, in order to produce blurred reflections, it’s necessary to use a shader that supports glossy reflections. Many PBR shaders offer a glossy function.
When it comes to adding fill light, we have two basic choices:
1. Add one or more lights to simulate light bounce. These might be directional lights, area lights, or an ambient light.
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Figure 6.3 White line indicates edge of a shadow, which in
turn indicates the angle of the incoming sun light. Arrows
point to bright spots, which give additional clues.
Figure 6.4 Approximate translation, rotation, and scale of key area light.
Figure 6.5 Initial render with key area light and ray trace shadows.
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2. Activate a PBR lighting or rendering system that bounces light.
You can also combine these two techniques. For example, in Figure 6.6 and 6.7, a second area light is added as fill. Its intensity is significantly lower than the key. Final gather is activated to add an additional degree of sec-ondary diffuse illumination. Alternatively, you can use another form of GI, such as photon mapping. Replacing the ray trace renderer with a path tracing renderer would produce similar results. The addition of GI adds light bounce to the corners and edges surrounding the elevator doors. In addition, GI raises the overall brightness of the image, bringing it closer to the original photo. Note that additional improvements can be made by refin-ing the shaders and textures; for example, adding bump or normal maps can help increase the realism.
Figure 6.6 A second area light is added as fill
light.
Figure 6.7 Final render. Although improvements can be made to the texturing, the lighting mimics the original photo.
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Location #2: Bus Interior
For the second location, we’ll reproduce the interior of a bus (Figure 6.8).
As a first step, we’ll ask basic questions about the location:
What is the location of the lighting? Interior of a bus with large bank of windows on all sides.
What is the time of day? Daytime.
What are the properties of the light sources? This will be 2-point lighting:
A) Sun light as a key, arriving from frame right.
B) The net sum of bounced sun light as a fill. The light reflects off the seats, floor, and ceiling.
The next step is to determine what 3D lights to use within the 3D program and if any specialized PBR lighting or rendering systems are to be used. A 3D model of a bus is illustrated by Figure 6.9. Materials are assigned with textures derived from the photograph. This 3D scene is included with the exercise files as bus.fbx. The rendering camera is named renderCamera. The textures are also included in the Textures folder. (See the Intro-duction for more detail on the available files.) The 3D model is not an exact copy of the bus but it should serve to demonstrate lighting approaches.
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Figure 6.8 Photo of bus interior.
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There are several paths we can take when lighting this scene:
• Light with standard lights, such as a directional as a key and a second directional as a fill. • Use an IBL environment light with a photo of the real outdoor location in combination with GI. • Use a sky system that emulates sun light in combination with GI.
The advantage of using a sky system or IBL environment light and GI is the relative ease of set-up. However, such setups generally require longer render times than standard lights. As an example, Figure 6.10, the mental ray Physical Sun & Sky system is activated, along with final gather. Like many sky systems, the Physical Sun & Sky system provides the option to choose the angle of the sun and relative time of day. This, in turn, affects the sun color. The sky color is also provided by the system, along with a virtual horizon line (although this is hidden below the bus).
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Figure 6.10 The initial render with a sky system. The light bounce is weak, creating darkness in much of the bus. The arrows
indicate the approximate direction of the sun.
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One potential problem, as seen in Figure 6.10, is the relative weakness of bounced light. This is due to the compact and cluttered interior of the bus which limits the amount of sun light entering through the window and limits the amount of light reflecting back to the camera. In this situation, you can add additional lights to provide extra fill. For example, you can add an ambient light with a low intensity. (Sky systems generally work with standard lights.) Another solution calls for the artificial increase in light bounce or, more precise-ly, secondary diffuse illumination weight. For example, you can multiply the intensity of secondary diffuse illumination by an arbitrary value. Final gather, as provided by mental ray, includes a Secondary Diffuse Scale attribute for this purpose (Figure 6.11). It’s not possible to increase the primary illumination via the sky system sun intensity as it will overexpose the right side of the frame.
Location #3: Outer Space
For the third location, we’ll replicate outer space. In this case, a space shuttle is orbiting the Earth (Figure 6.12). As a first step, we’ll ask basic questions about the location:
What is the location of the lighting? Outer space.
What is the time of day? There is no “time of day” beyond the surface of the Earth. However, we do know that sunlight is reaching the camera.
What are the properties of the light sources? This will be 2-point lighting:
A) Sun light as a key, arriving from the top of frame so that the shuttle is lit from behind.
Figure 6.11 Final render with an increased Secondary Diffuse Illumination scale.
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B) Fill light in the form of sun light reflected off the surface of the earth. If the spaceship was travel-ing between planets, the shadow side would receive virtually no light and would appear black.
The next step is to determine what 3D lights to use within the 3D program and if any specialized PBR lighting or rendering systems are to be used. A 3D model of the scene is illustrated by Figure 6.13. Basic materials are assigned with custom bitmap textures. A simplified version of this 3D scene is included with the exercise files as shuttle.fbx (this FBX includes a model created by Jafit, licensed via Creative Commons Attribution 3.0 Unported). The rendering camera is named renderCamera.
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With this scene, we can use directional lights to represent the sun and bounced sunlight. This is an ideal place to use directional lights as they have direction without position while representing a light source that is infinitely far away (or sufficiently far away to create parallel rays). You can determine the sun light direction by examining shadows within the photo (Figure 6.14).
Figure 6.15 includes an initial render with two directional lights. The key light casts depth map shadows. The key light intensity is ten times stronger than the fill light, creating a 10:1 lighting ratio.
Figure 6.14 White line indicates edge of a shadow created
by the shuttle tail and engine pod. Red arrow points to
light bounce.
Figure 6.15 The lighting is copied using two
directional lights.
Key
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At this point, there is missing light bounce. In particular, the light reflected off the shuttle’s tail fails to add light to the engine pod area (see Figure 6.14). Once again, we have the option of adding an additional fill light, acti-vating a PBR system with light bounce, or doing both of those things. For example, in Figure 6.16, GI is added with photon mapping. The key light is made to emit photons. Note that the activation of a GI system may necessitate the readjustment of existing lights. With this example, the key light intensity was reduced slightly. In addition, photon mapping systems often allow you to adjust the intensity of the secondary diffuse illumina-tion contribution. For example, with the mental ray renderer, the Global Illumination Scale attribute allows you to increase or decrease the secondary diffuse illumination contribution. For Figure 6.16, the contribution was lowered to 0.25 or 25 percent.
Designing Character LightingIn this section, we’ll light a character in an interior space. This will give us the opportunity to light a location without the presence of sunlight. The character is a devil woman. The interior space is a dungeon (Figure 6.17).
Because character lighting is a unique subset of lighting, you can ask unique questions:
Is the goal to make the character handsome or beautiful? If so, consider using glamour lighting. For example, apply 1-point soft lighting or 2-point butterfly lighting.
Is the goal to make the character unattractive or hideous? If so, you can apply stylistic lighting com-mon to horror or science fiction films, such as placing lights at unusual angles, allowing shadows to lie in an ugly fashion, or using unusual light colors.
Figure 6.16 Photon mapping adds light bounce
to engine area, as indicated by the red arrow.
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Is the goal to light the character aesthetically without exaggerating the beauty of hideousness? If so, use one of the common lighting techniques developed for painting, photography, or cinematogra-phy. For example, employ Rembrandt lighting, loop lighting, or split lighting.
Is the goal to communicate the character’s mental state or evoke a particular mood? If so, consider altering the light color and light intensity to match the mood. For example, if the character is happy, use a warm, bright light. If the character is sad, use a dim, blue light. Light placement can also affect the result. Placing the key light so the eyes are shadowed will strengthen the feeling of sadness or gloom.
The answers to the character questions produce the following goal:
To light the devil woman in an aesthetic manner without any specific desire to communicate information. The location itself and the associated lighting will provide the general mood of spookiness.
After you’ve answered the character questions and developed a goal, you can ask standard questions about the location. Ultimately, you must weigh your desire to light the location with your desire to light the charac-ter. To make the character appear as he or she is at the location, and not pasted on top, the character lighting must relate to the location lighting.
Here are the first two location questions with answers:
What is the location of the lighting? A dungeon without windows.
What is the time of day? There is no way to tell the time of day. It’s assumed the space is lit solely by torch light. One torch model is visible in the far background. If there are other torches, they are out of frame.
To determine the light sources and their properties, it’s necessary to return to the character answers. In order to light the girl in aesthetic manner, we can experiment with Rembrandt, loop, and split lighting. For example, in Figure 6.18, a directional light is used as a key to represent an unseen torch that rests somewhere out of frame to the left. The dungeon model is temporarily hidden to concentrate on the character lighting.
Figure 6.17 The devil woman and dungeon model.
The rendering camera is indicated by the green icon.
This model is not included with the exercise files
due to licensing issues. However, the dungeon
model is available at turbosquid.com and is listed
as “Torture Chamber.” It was created by CColeman.
The devil woman model is based on the “Rigged
Cartoon Female Hero,” which was modeled by
Disruptive Publishers and is available at the same
site. If you are unable to use these models, you
can practice the techniques with the girl.fbx file
provided for Chapter 4.
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With the key light in place, we can move onto additional lights. For this scene we can use 3-point lighting for the woman (a key, a fill, and a rim) and 2-point lighting for the dungeon (a utility light that serves as a second key and a fill light). The rim light will help separate the woman’s frame-right shoulder from the background. The utility light will illuminate the dungeon wall where the torch model is visible.
For a fill light, we can use a directional, spot, or point light. We’ll assume the light source is unseen and arriving from frame right. Figure 6.18 illustrates the addition of a point light with different intensity values that create different lighting ratios.
Figure 6.18 Left: The woman is lit with a key directional light. Standard Rembrandt lighting works well, although her right eye is shadowed by her
hair. Middle: Split lighting fails to light her eyes and leaves the majority of her face in shadow. Right: The best compromise is a form of loop lighting
where the key is kept a little lower so the nose shadow is further from the mouth. Note that shadows formed by the hair and lips must be considered
along with the nose to develop a good key translation or rotation. Due to the dark orange skin of the character, the key light is left with a white color
and is given an intensity of 2, which is twice the strength of the default setting.
Figure 6.18 Left: A point light is added as a fill and is placed outside of the frame to the right and at waist height. The lighting ratio is 2:1, creating
too much light. Middle: The lighting ratio is changed to 4:1. Right: The lighting ratio is set to 8:1, creating the best result. Because the location is in a
dungeon, low key lighting with high contrast is appropriate.
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Note that finding a good translation and rotation for a fill light takes experimentation. With Figure 6.18, shad-ows are deactivated for the fill light. We’ll assume that the fill source, which is most likely a torch or torch light reflected off the walls and floor, creates an extremely soft shadow that won’t be visible. Due to the shader as-signed to the woman model, the fill light creates an additional set of specular highlights. These interfere with the clarity of the woman’s face. To avoid this, we can deactivate the Emit Specular property of the point light. If this property was not available, adjustments to the assigned shader might be warranted. With the addition of the fill light, it’s a good time to adjust the shadow of the key light. By default, the shadow is hard-edged, which doesn’t match the quality of a torch. We can soften the shadow by raising the virtual width or radius and improving its rendering quality (Figure 6.19).
We can now add a rim light to help define the woman’s frame-right shoulder and arm. We’ll pretend the light arrives from the torch model in the background. A directional light works well with an intensity a quarter that of the key (Figure 6.20). You must experiment with the light’s rotation to produce a thin rim. Shadows are use-ful for this light as the shadows will prevent the rim light from reaching the front of the woman (for example, along frame-left hand or arm).
Figure 6.19 The second set of specular highlights are removed
by deactivating the Emit Specular function of the fill light.
The key light’s shadow is softened by raising the light’s virtual
width/radius.
Figure 6.20 A thin rim is added to the woman’s
frame-right shoulder and arm, courtesy of a
directional rim light.
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At this stage, we can display the dungeon and finish the lighting in the location. It is by no means necessary to start the lighting process with the character. It may be equally valid to establish the location lighting before moving on to the character. In this case, it’s tempting to allow the key and fill lights to illuminate the dungeon model. However, this leads to unattractive results (Figure 6.21). As a workaround, we can rely on the utility light to light the dungeon. This requires the use of light linking. The light links between the key and the dun-geon and the fill and the dungeon must be broken so that the dungeon receives no key and fill light.
Character Lighting PitfallsCharacter lighting carries its own set of quality considerations. Here are a few issues to watch out for:
Eyes and teeth Due to their general whiteness, eyeballs and teeth are easy to overexpose. If you don’t have access to the shader properties because you are working on a team project, consider using light linking to give the eyes and/or teeth their own lights with appropriate intensities. At the same time, eye models are often assigned to materials that use reflectiv-ity to add realism. If you are using a PBR rendering system, the reflections may appear too strong. Once again, you can link the eye models to their own set of lights. Conversely, you can use linking to force the eye models to simply ignore problem lights.
Tongues and mouths Mouth interiors may render too brightly. This may occur due to a lack of proper shadowing. The interior of a mouth should receive a shadow from the upper jaw, lower jaw, lips, and teeth. If shadows are activated but are not shadowing the interior or tongue, adjust the shadow properties. A depth map shadow with a low resolution or a high edge softening may cause the mouth shadows to disappear.
Dirty skin Excessive shadowing on the face may cause the skin to look dark and unhealthy. If this occurs, experiment with different light translations and rotations. With animated char-acters, it will be necessary to test render at various frames across the timeline.
Special shaders and systems Character models are often assigned to special shaders that employ advanced shader functions such as sub-surface scattering. As such, they often require different light adjustments when compared to surfaces with more mundane shader assignments. For example, due to translucence, rim, back, or hair lights may cause too much light to scatter through thin areas of the model, such as the ears. Characters may also pos-sess special effects systems, such as hair and cloth simulation, which may react differently to the lights in the scene.
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We can use a point light as a utility light. The omnidirectional style of the point light mimics fire light that would be present around the background torch. The light is placed above the torch model and slightly out of frame at the top-right (see Figure 6.23). To create light falloff, light decay is activated. With this example, linear decay works suitably well. Using decay requires a high light intensity, such as 400. The light color is changed to yellow-orange. To make the dungeon appear more gloomy, soft-edge depth map shadows are activated for the utility point light. This light is light-linked to the dungeon but is not linked to the woman, her hair, or her dress. The rim light acts as if its light arrives from the background torch. The utility point light serves the additional purpose of creating a bright background area that helps define the edge of the woman’s dark hair.
As a final step, we can add a fill light to the dungeon. Once again, this light should be linked to the dungeon but not the woman. The fill should be strong enough to fill in the black areas but not strong enough to make the background overly busy. For example, a lighting ratio of 8:1 works for the utility light and additional fill light. With this set-up, we want the focal point to remain on the woman. With the addition of the final light, you can consider re-balancing the intensities of all the lights, although the values work well with this example. Figure 6.22 and 6.23 represent the final render.
Figure 6.21 When the key and fill light illuminate the
dungeon, the shot becomes less attractive. The dungeon
walls appear to be flatly lit. In addition, the white light
color does not look like light from a fire.
Figure 6.22 Detail of final render. The updated lighting
on the dungeon makes the woman fit into the environ-
ment. In addition, the bright door allows the edge of
the woman’s dark hair to be seen.
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Measuring Light in StopsCinematographers, videographers, and photographers will often measure light on a location in stops. A stop is a measure of exposure relating to the doubling or halving of the amount of light exposing the frame. You can use lighting ratios when employing stops, although the relationship will be different due to the doubling and halving of light. For example, a 2:1 lighting ratio using light levels represents 1 stop difference between the key and fill. A 4:1 lighting ratio using light levels represents 2 stops difference between the key and fill. In other words, a 4:1 lighting ratio using light levels is the same as a 2:1 lighting ratio using stops. Although key-to-fill lighting ratios are often used, other relationships might be considered. For example, a key-to-background ratio may be use-ful. In this situation, background refers to the intensity of light reflecting off the background, as with an interior, or arriving from the background, as with an exterior. In the real world, the adjustment of stops is dependent on the camera’s shutter speed, aperture diameter, and film or video speed (light sensitivity).
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Figure 6.23 The final render. The arrow points to the position of the utility point light.
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Chapter 7: Designing Stylistic Lighting
Stylistic lighting is the opposite of naturalistic lighting. Hence, stylistic lighting does not have to follow the conventions or constraints of the real world. Nevertheless, stylistic lighting, like all lighting, should have specif-ic goals.
This chapter includes the following critical information:
• Ways in which stylistic lighting can generate moods or create unconventional looks • Stylized 3D lighting examples
“Light-painting, by Marko 93, in Paris.“ by Marko 93 licensed via Creative
Commons Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0).
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Stylized PlanningThus far, we’ve lit scenes that match real-world locations or otherwise follow real-world lighting conventions. In contrast, creating stylized lighting frees you from those bounds. Nevertheless, it’s important to plan out the lighting. As such, you can break the goals of stylized lighting into one or more of the following categories:
• Generating a mood • Creating a tribute to other art forms • Creating a visually unconventional look • Establishing a parallel world or timeline
Generating a MoodAs discussed in earlier chapters, lighting can inspire specific moods. For example, lighting used for horror, science-fiction, and fantasy projects often uses unusual light placement, low-key lighting, and unnatural colors to create a sense of dread and foreboding (Figures 7.1 and 7.2).
Mood can also apply to the characters themselves. For example, you can communicate a character’s mental state with the non-realistic placement of lights and shadows (Figures 7.3 and 7.4).
Figure 7.1 Detail of frame from the motion picture Psycho (1960). Silhouette lighting increases the tension by disguising the assailant. Although the
lighting appears accurate with a wall sconce in the background serving as a key light, the character is intentionally underexposed with little fill light
arriving from the front.
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Figure 7.3 Detail of frame from the motion picture Female Convict Scorpion: Jailhouse 41 (1972). A yellow-red back light bears little relationship to the
blue background; however, the light communicates a sense of pent-up anger and rage for the character.
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Figure 7.2 Screen snapshot from the video game Resident Evil 2 (1998). An overhead light on a bus serves as the
key light with little, if any, fill light. Although the lighting is equivalent to the same real-world location, and hence
naturalistic, the unattractive positioning of the key and low-key lighting supports the stylized horror theme.
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Creating a Tribute to Other Art FormsYou can use lighting to copy the unique style of another art form. For example, you can light a scene to mimic a particular school of art, the bold simplicity of illustration, or the colorful nature of abstract painting (Figure 7.5, 7.6, and 7.7)
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Figure 7.5 Detail of frame from the motion
picture The Cabinet of Dr. Caligari (1920).
The movie follows the artistic precepts of the
German Expressionist movement (early 20th
Century), which often included high contrast
and exaggerated, sharp angles within the art.
The film designers painted angular shadows
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Figure 7.4 Detail of frame from the motion picture Bram Stoker’s Dracula (1992). The shadow belonging to Dracula (in red) moves under its own
power, revealing the character’s true intent.
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Figure 7.6 Detail of frame from the motion picture Sin City (2005). The movie replicates the ink drawings of a graphic novel. Rim lights are extensively
used to define actors. Some elements are made unnaturally incandescent, such as the man’s glasses and shirt stripe. The film was shot on a green
screen set and was heavily altered in post-production to create the unique look.
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Figure 7.7 Detail of frame from the motion picture What Dreams May Come (1998). A character is placed within a
virtual painting by heavily manipulating the frames with 3D animation and 2D compositing. Despite the extensive
manipulation, the live-action lighting was matched to the particular painting the character was placed within.
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Creating a Visually Unconventional Look
Stylized lighting is sometimes applied to create an aesthetic that has simply not been seen before. In addition, the aesthetic might serve the dual function of creating unique art and supplying symbolism to the story. This might involve the application of unusual colors in a more traditional lighting context (Figures 7.8 and 7.9).
Figure 7.8 Detail of frame from the motion picture Paris, Texas (1984). Light from a parking deck flood light is left
a saturated green. Throughout the film, particular colors are associated with various characters. Although an actual
flood light has a non-white color wavelength, human vision adjusts to the light present and will not see such
saturated colors. To achieve similar lighting with a real-world shoot, you can tint the light with a gel, alter the light
colors with a camera lens filter, or alter the color timing in post production.
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Figure 7.9 Detail of frame from the motion picture The Neon Demon (2016). A combination of cyan and lavender light fills a
bathroom. Note the mismatch between the colors on the actress and sinks and the color of the light exiting the tops of the light
fixtures. Considered a unique take on the horror film genre, many non-traditional lighting setups are used throughout the film.
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3D animated films and video games, by their very nature, are fantastic. Nevertheless, they are often lit in a conventional way that follows the general rules of real-world lighting (Figure 7.10). Nevertheless, it’s possible to exaggerate the lighting so that it appears stylistic (Figure 7.11).
Figure 7.11 Detail of frame from the motion picture The Lego Batman Movie (2017). Background lights are heavily saturated, giving the scene a
magical appearance. Nevertheless, the characters themselves do not suffer from a heavy color bleed.
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Figure 7.10 Screen snapshot from the video game Grand Theft Auto V (2017). The game engine strives to create naturalistic
lighting that changes with the virtual time of day. Details include changing sky color, sun color temperature, corresponding
shadow quality, bounced light, and atmospheric glows.
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Establishing a Parallel World or TimelineStylized lighting can help establish a storyline that is out of sync with the main plot. For example, you might use stylized lighting for flashbacks or flash forwards. You can also use the lighting to indicate parallel worlds, such as those represented by dream sequences (Figure 7.12 and 7.13) or unearthly locations (alien planets, heaven, hell, and so on).
Chapter 7
Figure 7.12 Detail of frame from the motion
picture Spellbound (1945). One shot from a dream
sequence designed by Salvador Dali includes long
shadows that would be unusual in a relatively small
real-world interior.
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Figure 7.13 Detail of frame from the motion picture Shutter Island (2010). A dream sequence is indicated by lighting that does
not match the location through a strong overhead rim light. In addition, the female character is turned to ash and debris is floated
through the air with the aid of digital visual effects.
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Stylized 3D Examples
We can return to scenes featured elsewhere in this book and replace the lighting so that it becomes more sty-listic. For example, in Figure 7.14, the house model first featured in Chapter 4 is re-lit. The background sky plane is removed, revealing empty black behind the house. This creates the illusion of night time. Instead of using a directional light to emulate moon light, two spotlights are added with a purple color and a narrow cone angle. One spot is aimed at the back corner of the pool and one is aimed at the side wall at the right side of the frame (Figure 7.15). The purple light helps define the roof edge and back corner of the pool but does little else. The key light comes in the form of a red point light added to the interior of the house. The point light uses linear light decay. All of the lights produce soft shadows. The shape of the pool is mainly established by the reflection of the red interior.
With this example, the lighting does not match lighting you would normally see at such a location. However, the lighting does define the location in such a way that you can quickly identify it as a modern building with a pool. The unusual colors can help inspire moods such as anxiety and dread, or a sense of caution or danger.
Designing Stylistic Lighting
Figure 7.14 The house model is re-lit to create a stylistic look.
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“Style is a simple way of saying complicated things.” —Jean Cocteau
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As a second example, the girl model first seen in Chapter 4 is re-lit (Figure 7.16). Three directional lights are placed to the left, right, and above with equal intensity, a lack of shadows, and saturated orange color (Figure 7.17). A spot light with a narrow cone is aimed at the face with a green color. Two point lights with quadratic decay and red color have been placed close to the eyes. It’s hard to imagine a real-world lighting situation that matches this particular lighting set-up. However, the lighting might be useful for communicating the charac-ter’s emotional state or indicating a story point. Perhaps the character has been hypnotized, possessed by a spirit, or is actually an alien in disguise. Similar lighting may also be useful for indicating a dream sequence or a daydream.
Chapter 7
Figure 7.16 The girl model is re-lit to create a stylistic look.
Figure 7.15 Approximate positions and angles of the lights.
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As a third stylistic example, lighting painting is emulated (Figure 7.18 and 7.19). Light painting, as seen as the opening illustration in this chapter, captures light streaks through long exposures with real-world cameras. There are several ways you can emulate light painting in a 3D program, including:
• Animate an incandescent object moving through the scene at a high speed. Render with motion blur to capture a long blur streak.
• Deform geometry over time so it creates streak-like shapes. Convert to geometry into a mesh light or assign the geometry to shader that supports incandescence or glow.
• Use a visual effects system, such as particle simulation, to create movement of myriad objects. Assign the system to a shader that supports incandescence or glow.
Figure 7.18 utilizes the third method—fast moving particles assigned to an incandescent and glowing shader. Many programs allow you to artificially lengthen the motion blur trail for each frame or choose an extended virtual shutter length. (Normally, the blur length is based on the distance an object moves over one frame as restricted by the duration the virtual shutter is open for that frame.) With this example, the Arnold renderer was used. Arnold supports 3D motion blur, which is able to determine accurate particle positions along each motion blur streak. Hence, the motion blur streaks form curves. 2D motion blur, by comparison, is only able to create linear streaks regardless of their length.
Designing Stylistic Lighting
Figure 7.17 Approximate positions and angles
of the lights.
143
“The style depends on the subject.” —Mohsen Makhmalbaf
144
Chapter 7
Figure 7.18 Light painting is emulated in 3D with rapidly moving particles. Motion blur is applied by the renderer with a virtual
shutter set to a 12 frame duration. The extra-long duration causes the motion blur streaks to appear exaggerated and are equiva-
lent to the distance each particle moves over 12 frames.
Figure 7.19 Wireframe snapshot of light painting scene. White spheres are particles that move rapidly through the scene in a
circular fashion. A point light near the cactus provides light for the geometry.
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Motion Blur and Other Post-process Effects
Motion blur is a streaking of a moving object when the object is exposed for one frame of a video or for a single photo. The faster an object moves, the longer the streak appears. 3D programs usually offer motion blur as a render option. The blur is calculated during the initial render or is added as a post-process effect. A post-process effect is added after the initial render and is generally created as a 2D compositing step. For example, a post-process motion blur is created by adding a Gauss-ian-blurred version of the initial render on top of the moving object. Although motion blur is not intrinsically a part of lighting, it is an important component that adds realism to a 3D render.
Other post-process effects include depth-of-field and glow. Depth-of-field emulates circles of confusion where areas of a real-world photo or video lack focus and appear blurry. Glow is a form of halation where light is diffusely reflected off the internal mechanism of a lens or camera. Glow also occurs when light diffusely reflects off participating media, such as fog or smoke. Much like motion blur, depth-of-field and glow can lend realism to a 3D render.
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“The substance of painting is light.” —Andre Derain
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Case Study 1: Copying aRenaissance Still LifeWith this case study, we’ll replicate the lighting contained in a still life painting (Figure C1.1). Exercise steps are outlined for Autodesk Maya but can also serve as a general guideline for other 3D programs.
We’ll begin the exercise by answering important lighting questions introduced in Chapter 3:
What is the context of the lighting? We are matching the lighting contained in a painting as closely as possible.
What is the location of the lighting? Interior.
What is the time of day? The exact time is unclear. The reflections within the glass show a small win-dow through which daylight arrives.
What is the time period? 1600s. There are no artificial light sources.
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Case Study 1
What are the properties of the light sources? This will be 2-point lighting:
A) Sun light as the key light. The light streams through a small window at frame left. Based on the location of the reflection, the window appears to be high on the wall. Because the light is passing through a small portal, it becomes somewhat diffuse.
B) Net reflected sun light serving as fill. The light bounces off the table and surrounding walls.
Using Autodesk Maya with the V-Ray Renderer
1. Launch Autodesk Maya. Open the Still-Life-Start.ma file from the \Project-Files\Maya\ directory. Take a few minutes to familiarize yourself with the scene contents. The scene contains a mock-up of the painting (Figure C1.2). A camera named renderCamera is in position to duplicate the point-of-view of the painting. A second camera, named persp, is left as a work camera and is not intended for rendering. The model is not an exact reproduction of the painting but is close enough to duplicate the lighting. If you are not using Maya, a Still-Life-Start.fbx file is saved to the same directory.
Figure C1.2 The Maya scene with renderCamera
highlighted in green. Note that the ceiling,
floor, and several walls are single-sided so
that they do not block the camera or interfere
with the adjustment of lights. In addition, the
shadow-casting ability of those surfaces is deac-
tivated. (If you choose to import the FBX version
of this scene, you may need to deactivate
the Double Side attribute once gain for those
surfaces; the single-sided settings are ignored
by the FBX format used for this book.)
Reloading Missing Texture Bitmaps
The Maya scene files included with this book assume that the texture bitmaps are located in the C:\Project-Files\Textures\ directory. If the bitmaps are not at that location when you open the file, you will need to reload the bitmaps with the following steps for each texture: open the Hypershade window (Windows > Rendering Editors > Hypershade), double-click the texture icon in the Textures tab, click the File browse button in the texture’s Attribute Editor tab, and browse for the missing texture. Missing textures receive a black icon in the Hypershade. Alternatively, if you copy the texture bitmaps to the C:\Project-Files\Textures\ directory on your computer, simply choose File > Set Project and select the C:\Project-Files directory before opening the file.
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2. Depending on the version of Maya you are running, Maya renders with either the Maya Software or Arnold renderer by default. For this section, we’ll render with the Chaos Group V-Ray renderer, which is available as a plug-in. You can download a trial copy of V-Ray at www.chaosgroup.com. After V-Ray is made available, switch the renderer to V-Ray through the Select Renderer menu at the top of the Render View window. The V-Ray renderer has a capacity for PBR rendering depending on the render options selected and whether or not V-Ray PBR shaders are employed. For this study, however, we will start with V-Ray in its default state with standard Maya materials.
3. We’ll begin the lighting process by adding a key light first. We can use an area light to replicate a small window. Choose Create > Lights > Area Light. If you are using an older version of Maya, activate ray trace shadows for the light (with recent versions, ray trace shadows are activated by default). To facilitate the adjustment of the light, go to the renderCamera viewport and select Lighting > Use All Lights and Light-ing > Shadows. This shades the viewport to emulate the area light’s illumination and shadows. Set the light’s Intensity to 10 so that the shadows are easier to see. Position the light so that it sits high above the table and on the frame left side. Continue to adjust the area light translation, rotation, and scale until the shadows roughly match the shadows in the painting (Figure C1.3). Determining a translation, rotation, and scale that works well takes experimentation. Nevertheless, a Translate of –48, 60, 78, a Rotate of 347, –71, –9, and a Scale of 5, 5, 1 is suitable.
Copying a Renaissance Still Life
Figure C1.3 Top: The renderCamera
viewport with Use All Lights and
Shadows activated. The light trans-
lation, rotation, and scale is adjusted
based on the resulting shadow
shapes. The shadows are roughly
matched to the painting. Bottom:
Positioned key area light. The light
is able to pass through the wall and
ceiling because the ceiling and wall
geometry do not cast shadows.
Key
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4. Test render. V-Ray launches its own variation of the Render View window, named V-Ray Frame Buffer. The renderer progressively refines the entire frame until the render is complete or the render is interrupted by the user. In addition, any changes to lights, materials, or geometry during the render causes the render to actively update the affected parts of the frame. You can press the Esc key or click the Stop button at the window ‘s upper-right corner to interrupt a render (Figure C1.4). To restart the render, press the Start Interactive Rendering at the upper-right corner of the window.
5. Switch the light’s Decay Rate from None to Quadratic. This emulates light decay in the real-world. How-ever, the light’s Intensity must be increased significantly to affect the scene. Start with an Intensity of 250 and incrementally raise it until the table is as roughly bright as the table in the painting. It will be difficult to judge the lighting in the viewports due to the decay; thus, you must rely on the Frame Buffer window. Note that the scale of the area light also affects the required intensity—a smaller area light requires a higher Intensity value to match a larger area light. An Intensity value of 1,250 works well for an area light that is 5 world units wide and tall (Figure C1.4). An additional clue to the light’s ideal placement is the specular highlights on the objects in the scene. If the specular highlights roughly match the painting, the light’s position is fairly accurate (Figure C1.5).
Case Study 1
Figure C1.4 Render with the V-Ray
Frame Buffer with area light Decay Rate
set to Quadratic and Intensity set to
1,250. The red arrow points to the Start
Interactive Rendering and Stop Render-
ing buttons. The yellow arrow points to
the Display Colors In sRgb Space (which
is deactivated in this screen snapshot).
The cyan arrow points to the Render
Region button.
Gamma-Corrected Views
By default, Maya displays a gamma-corrected view within the Render View and V-Ray Frame Buffer windows. For these exercises, I recommend turning off the correction. In the Render View, turn off the View Transform button at the top-right of the window. In the V-Ray Frame Buffer, deactivate the Display Colors In sRgb Space button at the bottom-left of the window (see Figure C1.4). These buttons are useful when working in linear color space, where there is no gamma adjustment. How-ever, when working in non-linear color space, as we are in this book, the extra gamma adjustment makes the render look inappropriately bright, making it difficult to judge the lighting. An alternative approach requires the deactivation of the Enable Color Management attribute in the Color Man-agement section of the Preferences window (Windows > Settings/Preferences > Preferences). See Chapter 3 for more information on linear color space.
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6. We can now add a primary fill light. (Although we’ve determined that this is a 2-point lighting set-up, we will use more than two lights to achieve the desired look.) Choose Create > Lights > Directional Light. Rotate the light so that its illumination arrives from the opposite direction of the key light. You can scale the light icon to see it better. Scale and translation does not affect the light quality of a directional light. The new illumination is visible in the renderCamera viewport. The goal is to fill in the unlit portions of the objects. Test render. Slowly raise the new light’s Intensity until the fill lighting starts to match the painting. A rotation of roughly 64, 0, 94 is suitable (Figure C1.6). The new light starts to adds illumination to the cast shadows, making them brighter. Examining the shadow brightness helps to determine a good rotation for the directional light, although it is impossible to leave the shadows unaffected. Note that it’s not necessary to use shadows for the directional light. The directional light represents bounced light, or secondary diffuse illumination. Such illumination would create extremely soft shadows, which would be difficult to see. In the directional light’s Attribute Editor tab, deselect Use Ray Trace Shadows checkbox in the Shadows > Raytrace Shadow Attributes section (this attribute is selected by default with recent Maya versions). By the same token, it’s not necessary to create additional specular reflections on the surfaces with the fill light. Deselect the fill light’s Emit Specular checkbox (in the same section as the Color and Intensity attributes). Test render (Figure C1.7).
Figure C1.5 Top: Specular reflections in painting indicated with arrows. Bottom: Specular highlight indicated in
render. If the render and painting share similar specularity, then the key light translation, rotation, and scale is
fairly accurate.
Copying a Renaissance Still Life
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Case Study 1
Figure C1.7 The addition of a fill light prevents any part of the scene from remaining pure black and adds some light to back wall.
Figure C1.6 The fill directional light
arrives from a direction opposite the
key area light.
7. When testing, you can render regions in the V-Ray Render Buffer window by clicking the Region Render button at the top of the window so it turns blue, LMB-dragging a region box in the render area, and clicking the Start Interactive Rendering button at the top-right. To return to full-frame rendering, click the Render Region button so it is no longer blue. At this point, the back wall is missing the bright area on the left of frame. We can replicate this with a utility light. Rename the area light Key and the directional light Fill. Choose Create > Lights > Spot Light. Rename the spot light Background. You can rename a light by double-clicking the light’s name in the Outliner window (Windows > Outliner). You can scale up the spot light to better see it. Translate and rotate the light so that it illuminates the left side of the back wall. Change the light’s Cone Angle to 30 and Penumbra Angle to 7. Test render, slowly increasing the light’s In-tensity until the illumination is similar to the painting (Figure C1.8). An Intensity of 2.5 works well. A Trans-late of –86, 73, 35 and a Rotate of –15, –34, –24 is suitable (Figure C1.9). It’s not necessary for the spot light to cast shadows. In the spot light’s Attribute Editor tab, deselect Use Ray Trace Shadows checkbox in the Shadows > Raytrace Shadow Attributes section.
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8. At this phase, we can refine the shadows. One unique trait of the shadows in the painting is the dark cores and brighter, softer edges (Figure 1.10).
Figure C1.8 A spot light is added as a background light.
Figure C1.9 Position of the spot light. The light is able to
pass through the wall because the wall geometry does not
cast shadows.
Figure C1.10 Close-up of shadows in
the painting.
Copying a Renaissance Still Life
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Case Study 1
The only way to adjust the softness of the area light shadows is to adjust the size of the light. An alter-native solution requires the addition of a second shadow-casting light that will create a darker shadow core. To do this, create a second directional light and rename it Core. Rotate the light so it points down on the table at an angle similar to the area light. If not already activated, turn on ray trace shadows for the light. Test render. The goal is to overlap the shadows of the Core light with the shadows of the Key light so there is a darker center section and a lighter edge (Figure C1.11). The core light will brighten the Key light’s shadows. Set the Intensity of the Core light to 1.5. Lower the Key light intensity to 1,000. Lower the Background light Intensity to 2. Raise the Fill light Intensity to 1.5. It’s often necessary to re-balance all the light intensities when a new light is added. To soften the edge of the Core shadows, set the Core light’s Light Angle attribute to 20; this emulates a physically broad light or light scattered through a window. Light Angle is located in the light’s Raytrace Shadow Attributes section. As for the rotation of the Core light, a value of approximately –9, 64, 125 works well.
9. At this stage, it’s worth examining the render quality. The render possesses numerous fireflies, which are misplaced or isolated pixels that appear pure white (Figure C1.12). Fireflies are often the result of strong specular reflections generated in small areas. The fireflies are particularly evident along surfaces that use bump maps, such as the silver knife and the stemmed copper dish. Advanced renderers that employ some form of path tracing offer different quality options to combat fireflies. V-Ray provides several Render Settings attributes which include Max Ray Intensity and Use Embree. Max Ray Intensity, found in the Rendering section of the Overrides tab, suppresses reflection rays that are more intense than the attribute setting. Use Embree, found in the System section of the Settings tab, activates the Intel Embree Raycaster. Embree is a collection of ray tracing kernels (processor components) optimized for photorealistic render-ing. With Maya 2018, Max Ray Intensity and Use Embree are activated by default and therefore are unable to reduce the fireflies with this particular setup. Another solution calls for the use of materials/shaders designed for the renderer. For example, V-Ray includes a selection of PBR shaders that offer additional attributes for controlling reflectivity and specularity.
Figure C1.11 Render after addition of the Core directional light and re-balancing of light intensities.
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10. A third approach to combating fireflies calls for the adjustment of the current Maya materials. If material adjustment is permitted, as it is with this case study, you can quickly reduce fireflies by increasing the specular highlight size and reducing the specular intensity. For example, with a Blinn material, you can raise the Eccentricity value and reduce the Reflectivity, Specular Color, and Specular Roll Off values. We can improve our current render by adjusting the knife_mat and dish_mat materials (Figure C1.13). Fire-flies can be difficult to remove with each scene requiring a unique solution. Additional approaches to re-ducing fireflies may include using renderer-centric lights or adjusting the sampling of the renderer. V-Ray supplies its own light shaders that carry their own specular contribution controls. V-Ray, like all renderers, also includes its own set of sampling controls, which we will examine later in this chapter. A matching scene file is included as Still-Life-Vray-Final.ma in the \Project-Files\Maya\ directory.
Copying a Renaissance Still Life
Figure C1.12 Enlarged view of fireflies on knife handle. Although tightly packed on this surface, fireflies
may occupy a single pixel and may be isolated from other fireflies.
Figure C1.13 Fireflies are greatly reduced by
adjusting the specular attributes of the assigned
Blinn materials.
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““““““““ “I have always preferred the reflection of the life to life itself.” —Francois Truffaut
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Case Study 1
Switching to the Arnold RendererAlthough renderers share many qualities, switching between renderers may produce different initial results. For example, we can switch from V-Ray to Arnold renderer in Maya. This will present its own unique set of challenges. You can follow these steps:
1. Switch the Render Using menu in the Render Settings window to Arnold Renderer. Arnold is a PBR rendering system that uses path tracing to automatically calculate light bounce. Render a test frame with the Render View window. When you switch to a different renderer, you often need to adjust the assigned materials and lights (although this may be less of an issue if the scene uses PBR shaders with texture bitmaps mapped to all the critical shader attributes). Figure C1.14 shows what the render looks like after switching to Arnold.
Here are the most significant changes:
• The light intensities are different and the scene is much darker. By default, Arnold applies quadratic light decay to spot lights and area lights and linear light decay to directional lights. Lights with low values, such as the Background light, fail to illuminate the geometry.
• Some materials behave differently. For example, the glass surfaces have lost their transparency. Bump mapping via Maya materials is not supported (when using Maya 2017 or Maya 2018).
• All lights produce specular reflections. Hence, there are additional hot spots on the glass surfaces.• All lights in the scene cast shadows. The old shadow settings are overridden. As such, the shadow
edges have changed. Arnold applies its own default shadow edge quality.
2. To fix the light balance, set the Key light Intensity to 100,000. Finding new Intensity values takes test ren-dering and experimentation. Set the Background light Intensity to 100,000. You can leave the Fill and Core lights set to their previous intensities. Test render (Figure C1.15).
3. To return the shadows to their prior state, you can adjust the attributes in the Arnold section of each light’s Attribute Editor tab (Figure C1.16). For example, turn off Cast Shadows for the Background and Fill lights. For the Core light, set the Angle attribute to 20 and Samples attribute to 12. Angle sets the virtual width of the light. Samples controls the shadow rendering quality. Test render (Figure C1.17).
Figure C1.14 Switching to the Ar-
nold renderer produces drastically
different results.
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Figure C1.16 Arnold section included in each
light’s Attribute Editor tab. It’s not unusual for
an advanced renderer to include its own light
attributes or, alternatively, include its own
renderer-centric light types.
Copying a Renaissance Still Life
Figure C1.15 Arnold render after the adjustment of the key and background light intensities.
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“We cast a shadow on something wherever we stand.” —E. M. Forster
158
4. Adjusting the glass and water materials is more difficult. The Arnold renderer assumes all surfaces are opaque unless otherwise designated. To designate the glass and water surfaces as non-opaque, you can follow these additional steps:
a) Open the Outliner window (Windows > Outliner). Expand the table_scene, tumbler, and goblet hierarchies. Select the tumbler_top surface. Open the Attribute Editor (Ctrl/Cmd+A). In the Arnold section of the surface’s Shape tab, deselect the Opaque checkbox.
b) Repeat this process for the tumbler_base, goblet_top, goblet_base, and water_surface surfaces.
To correct the reflectivity, specularity, and color, you can adjust the diffuse, transparency, and specular attributes of the assigned Blinn materials until the desired look is met. Another solution calls for the assignment of the glass and water surfaces to PBR shaders supported by the Arnold renderer and adjust the attributes of those shaders. For example, you can assign the surfaces to Ai Standard Surface materials in Maya. To save time, I have included example Ai Standard Surface materials with the Still-Life-Start.ma file. (If you are using Maya 2017, you will need to create your own Ai Standard materials as the Ai Standard Surface materials are not compatible.) To assign these materials, follow these steps:
a) Go to the Outliner window. Expand the table_scene, tumbler, and goblet hierarchies. Select the tumbler_base, goblet_base, and water_surface surfaces. Open the Hypershade window (Windows > Rendering Editors > Hypershade). RMB-click over the Arnold_water material and choose Assign Material To Selection from the menu.
b) Select the tumbler_top surface and assign it to the Arnold_glass material.
c) Select the goblet_top surface and assign it to the Arnold_glass2 material.
Figure C1.18 shows the render after the assignment of Arnold materials.
Case Study 1
Figure C1.17 Render after the adjustment of shadows.
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Copying a Renaissance Still Life
Creating a Window ReflectionOne quality of the painting that we haven’t replicated is the reflection of the window with the distinct window cross bars. There are several ways you can create this. One approach would be to construct a more accurate version of the room, complete with surrounding walls and inset window with frame and bars. With such a model, you would place the key light outside the window. Another approach requires an array of six area lights. In fact, you can duplicate and scale the current Key area light. Figure C1.19 shows such an array. Each light is given a little less than one-sixth of the original intensity (12,000). At the same time, it’s necessary to adjust the specular qualities of the materials assigned to the glass surfaces. For example, we can adjust Weight (specular strength with the attribute located in the Specular section) and Roughness (glossiness) for each as-signed Arnold material. Note that each light continues to create a specular reflection. To remove the specular reflection of the Fill light, reduce the Specular attribute, in the Arnold section of the light’s Attribute Editor tab, to 0. The resulting render of lights and materials is shown in Figure C1.20.
Figure C1.18 The glass surfaces regain
transparency after deselecting the
surfaces’ Opaque checkbox and assigning
the surfaces to Arnold Standard Surface
materials.
“What difference does it make whether you’re looking at a photograph or looking at a still life in front of you? You still have to look.” —Chuck Close
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Case Study 1
Figure C1.19 The Key light is converted to an array of six
smaller and weaker area lights through duplication.
Figure C1.20 Window reflections are
emulated by creating an array of six area
lights. Path-tracing renderers, such as Ar-
nold, are able to create accurate specular
reflections of light sources.
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At this point, the new window reflection has not improved the specular reflection seen in the lid of the pocket watch at the left side of the frame. Once again, a quick solution requires the adjustment of the assigned mate-rial. We can adjust the Blinn material’s Eccentricity, Specular Roll Off, Specular Color, and Reflectivity attributes. To create a more accurate reflection, you can also assign the surface to a PBR shader, such as a an Arnold Standard Surface material. If adjustment of materials/shaders is not viable for a scene, you can link a unique light to the lid surface and unlink the lid surface from pre-existing lights. As such, you can adjust the new light to improve the render quality of the watch lid without affecting any other object in the scene (see Figure C1.22 later in this section).
When the renderer was switched to Arnold, the quality of the reflections in the glass surfaces also changed. For example, the goblet has a dark reflection along its frame-right edge. This is due to the frame-left wall remaining underlit by the more aggressive light decay of the renderer. One solution is to light the wall with a separate light. For example, in Figure C1.21, an area light is pointed at the frame-left wall while avoiding other surfaces. Due to the presence of light decay, the light requires a high Intensity of 25,000. Due to the inherent light bounce of a path tracing renderer, the addition of this light contributes bounced light to the wall seen by the camera. To avoid overexposure, we can reduce each Key area light to 10,000 and the Fill light to 1.25.
Another element that is missing from the render is the variation of reflection brightness on the glass surfaces. For example, the goblet in the original painting has dark areas along its center. This variation is due to the painting’s reflected room possessing different degrees of light and shadow along its walls and corners. We can emulate this by adding additional area lights that point toward to the wall behind the camera (Figure C1.21). With this example, the light intensity varies between 100,000 and 150,000 for the new lights. You can adjust the resulting reflections by adjusting the light translations, rotations, and scale. Note that the strength of the reflections when using PBR materials is partially dependent on the material’s refractive index setting. For ex-ample, if the material has a relatively low refractive index, such as 1.1, the reflections are weaker. If the material has a higher refractive index, such as 1.4, the reflections are stronger. (Aside from reflectivity, refractive indexes control the amount of distortion seen within the refractions.) Hence, fine-tuning the material attributes that control refractivity, along with reflectivity, may be advantageous. With the Arnold Standard Surface material, the IOR attribute, in the Specular section, sets the refractive index. Figure C1.22 shows a render resulting from these adjustments. For more information on refractive indexes, see Chapter 3.
Figure C1.21 Three area lights are added and point-
ed toward various walls. This creates more variation
in the glass reflections as the surrounding room
is no longer evenly lit. This also contributes to the
presence of additional bounce light which requires
the readjustment of the other lights in the scene.
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Case Study 1
Adjusting the Render QualityThere is always room to improve the lighting of a 3D scene. Aside from various qualities discussed in this chapter, it’s also important to consider the render quality as set by the renderer. There are two main areas to consider with this case study: sampling and ray trace depth. Sampling refers to subpixel sampling. Every 3D renderer offers a way to increase the subpixel sampling accuracy and thus improve the render quality. The higher the subpixel sampling value, the more samples are taken per pixel. The samples take into account the geometry, materials, lights, and shadows that fall within the pixel’s domain. The higher the subpixel sampling value, the greater the number of calculations required and the longer the render takes.
The V-Ray renderer includes sampling attributes in the Image Sampler section in the VRay tab of the Render Settings window. These attributes are demonstrated in Case Study 2. The Arnold renderer includes sampling attributes in the Sampling section of the Arnold Renderer tab of the Rendering Settings window (Figure C1.23).
Arnold divides the sampling between major shading qualities, including diffuse (non-reflective), glossy (reflective), transmission (refraction), and SSS (Sub-Surface Scattering). In addition, Arnold includes a Camera (AA) attribute to control the overall anti-aliasing quality. For example, with this case study, the Camera (AA) value must be raised to remove some of the fine grain that appears along shadow edges and within reflections (Figure C1.24). When adjusting the sampling values, raise them gradually and test render with each step. Small changes to the sampling values can have a significant impact on render times.
Figure C1.22 Render after the addition of area lights used to illuminate different parts of the surrounding room.
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Copying a Renaissance Still Life
In contrast, ray trace depth sets the number of times ray trace rays are permitted to bounce through a scene via reflections and refractions (transmissions). If ray trace depth is set to a small value, the render is efficient but may not be accurate as the rays may be killed off mid-way through a complex surface. For example, a low depth setting will not allow a ray to refract through the inner and outer surfaces of 3D vase. Low depth settings often create dark voids within transparent or semi-transparent surfaces.
Figure C1.23 The Sampling section of the Arnold
Renderer tab of the Render Settings window.
Figure C1.24 Left: Close up of bread shadow with the default sampling settings. There is a heavy grain present due to soft shadows and the placement
of multiple area lights. Right: Same area rendered with Camera (AA) set to 6 and Diffuse set to 3.
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The V-Ray renderer includes depth settings within the Materials section of the Overrides tab of the Render Settings window. The attributes include an optional Global Max Depth and Max Depth, which set the number of times a ray is allowed to reflect and/or refract before it is killed off. If Global Max Depth is left off, the render-er defers to the local depth settings of assigned materials. For example, Maya materials that support speculari-ty include Reflection Limit and Refraction Limit attributes in the Raytrace Options section. The Vray Mtl shader includes a Depth Max attribute in the Reflection - Advanced section.
The Arnold renderer includes depth settings in the Ray Depth section of the Arnold Renderer tab of the Render Settings window. These attributes are divided and named after various shading qualities. For example, Diffuse controls the number of diffuse reflection bounces (providing secondary diffuse illumination), Specular controls the number of specular reflection bounces (providing mirror-like reflections), and Transmission sets the number of refractive bounces.
With this case study, the default depth settings produce sufficient quality. The scene in its current state was also used for the cover render (Figure C1.25 and C1.26). With the cover, the objects were rearranged but the lighting was left intact. The final V-Ray scene is included in the \Project-Files\Maya\ directory as Still-Life-Vray-Final.ma. The final Arnold scene is included in the \Project-Files\Maya\ directory as Still-Life-Arnold-Final.ma.
Case Study 1
Determining Values
Throughout these case studies, I provide values for various attributes, such as light colors, light intensities, and shadow qualities. These values were determined through experimentation. In other words, I wasn’t able to derive the values without trying a wider range of values and test rendering. Experimentation is a necessary part of 3D lighting. A render rarely turns out perfect on the first try. At the same time, you should remain flexible enough to re-adjust the values as you proceed to add additional lights, shadows, and lighting effects.
SID
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Figure C1.25 The objects are rearranged to create the cover render.
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Figure C1.26 The cover render. The grayscale insert was created by temporarily assigning all the surfaces to a gray Lambert material and using a low
Camera (AA) value to intentionally create noise. The color insert is a screen snapshot of the renderCamera with Hardware Texturing activated.
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Case Study 2: Lighting a Complex Night Interior
With this case study, we’ll light an interior scene featuring a futuristic vehicle in a garage-like setting (Figure C2.1). Exercise steps are outlined for Autodesk Maya but can also serve as a general guideline for other 3D programs.
We’ll begin the exercise by answering important lighting questions introduced in Chapter 3:
What is the context of the lighting? We are lighting a single shot, so it does not need to match any particular source.
What is the location of the lighting? Interior.
What is the time of day? We’ll assume it is nighttime. Night scenes are often more difficult to light due to the dependence on multiple man-made light sources.
What is the time period? This is a science-fiction piece, so the time period is sometime in the near future.
Figure C2.1 The interior scene with renderCamera highlighted.
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What are the properties of the light sources? We’ll use a combination of naturalistic and stylistic light-ing with an arbitrary number of artificial light sources. Although we have no specific lighting reference, we’ll try to make the lighting look plausible for the location. As such, we will light with the following light sources:
A) Overhead light as a key. There is geometry in the scene that represents this rectangular bank of lights.
B) Outdoor light as fill. We will assume that there is an outdoor light, such as a floodlight, that reaches the interior through the windows and doors.
C) Incandescent wall trim as a utility light. There are narrow bands built into the wall that serve as futuristic light source. We can treat these bands as if they were neon tubes or arrays of LED lights. We’ll make these lights heavily saturated to create a stylistic look.
D) Vehicle lights as utility lights. A futuristic vehicle serves as the center of the scene. We’ll mimic dash lights, headlights, and small works lights.
In addition, we’ll add pool lights to illuminate parts of the scene missed by the other lights.
Using Autodesk Maya with the Maya Software Renderer
1. Launch Autodesk Maya. Open the Garage-Start.ma file from the \Project-Files\Maya\ directory. Take a few minutes to familiarize yourself with the scene contents. The scene contains a partial garage model, a vehicle, and a few props. A camera named renderCamera serves as the rendering camera. A second camera, named persp, is left as a work camera and is not intended for rendering. If you are not using Maya, a Garage-Start.fbx file is saved to the same directory.
2. In general, I suggest starting the lighting setup by placing the strongest key light or key lights. However, with this scene, we’ll start with a fill light that simulates an exterior light source that filters through the two small windows and the open side of the garage. Create a directional light (Create > Lights > Direc-tional Light). Feel free to scale up the light icon (it does not affect the light quality). Move the light away from the model so it is easier to see. Select the renderCamera viewport (click on the viewport panel bar to select it). Choose Lighting > Use All Lights and Lighting > Shadows from the viewport menu. By default with recent versions of Maya, ray trace shadows are activated for the light and are visible in the viewport. Rotate the light until the light creates a pattern on the floor by entering through one or more of the win-dows. You can allow the light to enter through the open side of the garage. We can treat the light as if it is also entering through a large, open garage door. For example, a rotation of approximately –149, 50, 12 creates the light pattern seen in Figure C2.2.
3. Create an area light (Create > Lights > Area Light). Position the area light until it is directly under the mod-eled light fixture located on the ceiling above the vehicle. This light will serve as the strongest light and the key. Scale the light so it is roughly the same size as the fixture. Rotate the light so that it points down-wards (Figure C2.3). (The light “tail” should point towards the floor.) Open the light’s Attribute Editor tab. Set the light color to yellow. Set the Decay Rate menu to Quadratic. Set the light’s Intensity value to1,000. (The large Intensity value is required because the light has a relatively small size within a relatively large set.) Open the directional light’s Attribute Editor tab. Set the directional light Intensity to 0.75 and Color to light purple. Although both lights receive ray trace shadow automatically, the directional light produces hard-edged shadows. Expand the Raytrace Shadow Attributes section for the directional light and set the Light Angle to 5; this makes the light rays divergent and softens the shadow edge.
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4. Now that there is a second light, feel free to adjust the rotation of the directional light. For example, rotate the light slightly so that it reaches the front of the vehicle. At any stage, you can return to a light and ad-just its transformations and attribute values to improve the overall lighting quality. Change the direction-al light’s name to window_fill. Change the area light’s name to key. You can change an object name by double-clicking the name in the Outliner (Windows > Outliner) and typing a new name.
5. Open the Render Settings window (Windows > Rendering Editors > Render Settings). Set the Render Using menu to Maya Software. Although the Maya Software renderer is not a PBR renderer and offers few options, it produces sufficient quality to begin the lighting process. (If you are using different 3D software, you can select an equivalent default renderer.) Switch to the Maya Software tab, expand the Raytracing Quality section, and select the Raytracing checkbox. Ray tracing is necessary to render the ray trace shadows. Create a test render of renderCamera through the Render View window (Windows > Rendering Editors > Render View). Note that the render quality is poor by default. You can raise the render quality by changing the Edge Anti-Aliasing menu to High Quality through the Maya Software tab of the Render Settings window. The ray trace shadow quality will remain poor and appear grainy; we will improve the shadow quality in a later step. The initial render is illustrated by Figure C2.4. I suggest turning off the View Transform button provided by the Render View as it shows a gamma-adjusted version that appears too bright. See Case Study 1 for more information on this option.
Figure C2.2 A directional light is rotated to serve as an
exterior light reaching the interior of the garage. The
black area of the floor represents a ray trace shadow.
Figure C2.3 An area light is translated,
rotated, and scaled under the modeled
light fixture. The light points downwards.
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6. The cyan trim seen along the walls appears incandescent, thanks to the assigned material, but does not light the scene. We can use additional area lights to add cyan light to nearby surfaces. Create a new area light and scale, rotate, and translate it to match the first bank of trim along the bottom of the left wall. Point the light outward towards the vehicle. The light can intersect the floor of other nearby geometry such as the round hatch and spare wheel. Open the new light’s Attribute Editor tab and set the light color to cyan. Set the Decay Type to Linear and the Intensity to 3. A linear decay requires a far lower Intensity value than quadratic decay. That said, we want the cyan light to only reach a short distance into the room. Test render (Figure C2.5). Change the new light’s name to trim_fill.
Figure C2.4 The area light, placed under the modeled light fixture, serves as the key light. However, due to light decay, it does not reach all parts of the scene
at equal intensity. The directional light is given a weaker intensity, a softer shadow, and is rotated to reach the front of the vehicle. The cyan of the wall trim
and the white of the headlights and small work lights comes courtesy of material incandescence; the incandescence does not light nearby surfaces.
Figure C2.5 A second area light is added
to emulate cyan light generated by the
incandescent trim. Note that the light
does not reach the wall itself; this can be
addressed in a later step.
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7. Duplicate the newest area light three times (Edit > Duplicate with the light selected). Scale, rotate, and translate the three copies so that they provide cyan light for the other three sections of trim (Figure C2.6). Because there is little geometry near the top pieces of trim, you can point the corresponding lights towards the walls.
8. Following a similar process, we can create light for the small white work lights that appear near the vehi-cle. However, instead of using area light, point lights are more appropriate for light bulbs. Create a new point light (Create > Lights > Point Light). Translate the new light so it sits directly beside the work light that hangs down near the vehicle’s front, frame-right bumper. Change the light’s name to work_fill. Open the light’s Attribute Editor tab. Set the light’s Decay Rate menu to Quadratic. Set the light’s Intensity to 5. We want the light to only illuminate a small area near the front of the vehicle. Duplicate the point light. Move the copy beside the cluster of three work lights that hang down on the visible side of the vehicle. We can use this light to emulate the illumination of all three lights as they are in close approximation. Set the new light’s Intensity to 10. Test render (Figure C2.7).
9. We can assume that the futuristic vehicle includes lighting in the cockpit. We can use this lighting to better define the seats and transparent, reflective canopy. Create a new point light. Change the new light’s name to cockpit_fill. Change its color to red. Translate the light so that it sits in front of one of the two screens built into the dash (Figure C2.8). Don’t let the light intersect any geometry (this will create un-wanted shadows). Point lights, like directional and area lights, are given ray trace shadows by default with recent versions of Maya. Set the light’s Decay Rate to Linear and Intensity to 4. Test render. The red light fails to reach the back seat as it is shadowed by the front seat. Duplicate the light two times. Translate one copy to the opposite side of the dash. Translate the second copy behind the front seat so it illuminates the back seat. Set the Decay Rate of the third light to Quadratic so that it is weaker. Test render (Figure C2.9). Note that the red light reaches the side wall and appears as a red refraction and weak reflection on the canopy.
Figure C2.6 Wireframe showing the locations of the four area lights providing illumination for the incandescent trim. The two top
lights point outwards and the two bottom lights point inwards.
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Figure C2.7 Render after the addition of area lights for the incandescent wall trim and point lights for the small work lights.
Figure C2.8 Positions of three cockpit point lights indicated by the red arrows.
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Figure C2.9 Render after the addition of the red cockpit lights. The red light reaches the wall, making the otherwise plain wall
more interesting.
10. At this stage of the project, almost every portion of the scene receives some degree of light. However, the wheels remain very dark. The wheels facing the camera have almost no detail. We can remedy this by adding stylistic pools of light. Create a new point light. Change the light’s name to pool. Move the point light so that it sits near the rim of the back screen-right wheel (Figure C2.10). Change the light color to yellow, the Light Decay to Quadratic, and the Intensity to 400. We will pretend that the yellow light is re-lated to the overhead light, although no specific light fixture for this light is visible. Test render. Duplicate the light. Move the copied point light so that it sits near the screen-right corner of the front bumper (Fig-ure C2.10). Change the light color to white and the Intensity to 750. We will pretend that the white light arrives from a nearby work light although it is not physically accurate. Test render (Figure C2.11).
Figure C2.10 Positions of point lights placed near wheels
indicated by red arrows.
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Figure C2.11 Render after addition of point lights near the wheels.
Light name Intensity value Color Color value (RGB with 0 to 1.0 scale)
key 700 Desaturated yellow 1.0, 1.0, 0.5
cockpit_fill, cockpit_fill1, and cockpit_fill2
3 Red 1.0, 0.125, 0.125
trim_fill, trim_fill1, trim_fill2, and trim_fill3
2 Cyan 0, 0.7, 1.0
window_fill 0.5 Desaturated violet 0.9, 0.5, 1.0
work_fill 3 White 1.0, 1.0, 1.0
work_fill1 5 White 1.0, 1.0, 1.0
pool 3 Desaturated yellow 1.0, 1.0, 0.5
pool1 1 White 1.0, 1.0, 1.0
11. At this stage, it pays to examine the overall quality of the lighting. All the major light sources have been established with numerous lights. However, the saturated nature of the lights makes the result somewhat jarring. To avoid this, you can fine tune the light intensities and colors. For example, in Figure C2.12, the adjustments listed in Table C2.1 are made.
Table C2.1
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12. The shadows currently visible in the scene are a product of the included geometry. That said, you are not limited by included geometry and can create additional shadows by creating 3D light flags. A light flag is a device used in photography and cinematography to block light; this often comes in the form of a fabric-covered frame. You can use any geometry in Maya to cast shadows; as long as the geometry is not visible in the render, it can serve as a flag. For example, create a primitive polygon helix (Create > Polygon Primitives > Helix). Translate, rotate, and scale the helix so it sits below the key area light (Figure C2.13). Test render. The helix serves as a flag, creating a new shadow on nearby surfaces. However, the helix is visible in the render. To avoid this, select the helix, go to the helix shape tab in the Attribute Editor, expand the Render Stats section, and deselect the Primary Visibility checkbox. Test render. Although the helix disappears from the render, it continues to cast shadows (Figure C2.14). Continue to adjust the translation, rotation, and scale of the helix until it forms an interesting shadow. Ideally, the new shadow breaks up the otherwise plain floor on the right side of frame and reduces the intensity of the yellow light on the back of the vehicle. Note that the shadow cast by the helix is soft-edged if the helix is close to the area light and more hard-edged if placed further from the light (and closer to the surfaces receiving the shadow). Optionally, you can add additional polygon objects to create more complex shadows.
Figure C2.12 Render after the adjustment of all the Intensity and Color values of all the lights in the scene.
Figure C2.13 A primitive polygon helix is translated, rotated, and scaled so that it sits
below the key area light at an angle. The helix serves as a light flag, creating a new
shadow.
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13. Thus far, we have rendered with low-quality shadows that create grainy shadow edges. You can improve the shadows by raising each light’s Shadow Rays value. The higher the Shadow Rays value, the smoother the shadow edge but the longer the render time. Thus, it’s best to incrementally raise the values and test render with each step until the render quality is satisfactory. For example, the values listed in Table C2.2 are used for the lights to create the render seen in Figure C2.15.
Table C2.2
Figure C2.14 Resulting render with a new shadow running from the right side of the left wall, down across the back right edge
of the vehicle, and ending across the frame-right floor. The shadow location is indicated by the red line. The helix is not visible
because its Primary Visibility checkbox is deselected. The new shadow adds visual interest by breaking up areas that possessed
consistent brightness or color.
Light name Shadow Rays value
key 32
cockpit_fill, cockpit_fill1, and cockpit_fill2 16
trim_fill, trim_fill1, trim_fill2, and trim_fill3 8
window_fill 16
work_fill and work_fill1 16
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When working with point lights, you have the option of changing the light’s virtual width through the Light Radius attribute. Shadow Rays and Light Radius are located in the Ray Trace Shadows section of the light’s Attribute Editor tab. The larger the Light Radius value, the wider the light and the softer the shadow it creates. For example, you can set the Light Radius of the work_fill and work_fill1 lights to 3. Note that larger Light Radius values may require higher Shadow Rays values to create suitably high-quality shad-ows. At the same time, you can determine if any lights do not require cast shadows. For example, you can deactivate shadows for the pool and pool1 lights with little change to the resulting render seen in Figure C2.15. A matching scene file is included as Garage-Maya-Final.ma in the \Project-Files\Maya\ directory.
Figure C2.15 Render after the adjustment of the shadow attributes. Most of the grain associated with low-quality shadows is removed.
Switching to the V-Ray Renderer and Adding Fog
We can further improve the vehicle scene by switching to the Chaos Group V-Ray renderer and employing PBR to capture bounced light. In addition, we can emulate airborne dust and smoke by using volumetric fog. You can download a trial copy of V-Ray at www.chaosgroup.com.
1. Open the Render Settings window. Switch the Render Using menu to V-Ray. Test render. V-Ray launches its own variation of the Render view window, named V-Ray Frame Buffer. The renderer progressively refines the entire frame until the render is complete or the render is interrupted by the user. In addition, any changes to lights, materials, or geometry during the render causes the render to update the affected parts of the frame. You can press the Esc key or click the Stop Rendering button at the window ‘s up-per-right corner to interrupt a render. To restart the render, press the Start Interactive Rendering at the upper-right corner of the window. See Case Study 1 for more information on this window.
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2. Disable the Display Colors In sRgb Space button at the bottom-left of the V-Ray Frame Buffer window. This prevents an additional gamma correction from being applied to the render (the button is designed to preview linear color space renders, which does not apply to our project). With the button disabled, the render is nevertheless too bright (Figure C2.16). Because the scene uses standard Maya materials, which are not designed for PBR, the lighting does not translate directly to V-Ray. In addition, the various area lights are rendered as solid objects by V-Ray. The area lights that face away from the camera are rendered as black planes.
3. Open the trim_fill light in the Attribute Editor. In the Object Display section, deselect Visibility. This hides the light from V-Ray render and the viewports. Repeat this process with trim_fill1, trim_fill2, and trim_fill3. We will gain back the blue fill through V-Ray rendering at a later step. Deselect Visibility for the key light. We’ll replace the key light with a new V-Ray Rect light. V-Ray, like many advanced renderers, provides its own lights. These offer the advantage of maximum compatibility with the renderer and often include spe-cialized options. Choose Create > Lights > V-Ray Rect Light. Translate, rotate, and scale the new light so that it is roughly in the same position as the Maya key light. The light appears similar to Maya area lights but has a more distinct arrow indicating the direction of light flow. Name the new light VRayKey. Open the light’s Attribute Editor tab. Set the light color to pale yellow (1.0, 1.0, 0.5 in RGB ). Set the Intensity Multiplier to 15. Note that the light is tailored for PBR by allowing you to set the intensity through such scale units as lumens or watts through the Units menu. Expand the Options section and select the Invisi-ble checkbox. Test render. The lighting is similar to the Maya Software render (Figure C2.17).
4. The blue trim along the bottom of the walls create blue fill on the ground as a specular reflection. Hence, the original area lights in those regions are not needed. At this point, several surfaces appear too reflec-tive, producing intense specular reflections. For example, the tires and seats possess increased specu-larity. Ideally, you can replace all the materials with V -Ray variations. This would allow you to add PBR accuracy to the material interpretation. V-Ray, like many advanced renderers, includes a library of com-patible shaders accessible through the Hypershade window’s Create menu. As a shortcut, we can simply adjust a few of the Maya materials currently in the scene. Open the Hypershade window. Double-click the tire_mat material, which is a Phong. In the Attribute Editor, go to the Specular Shading section. Reduce the Cosine Power and Specular Color to low values. This darkens the specular reflection and makes the surface appear more matte-like. Test render. You can render regions in the V-Ray Render Buffer window by clicking the Region Render button at the top of the window so it turns blue, LMB-dragging a region box in the render area, and clicking the Start Interactive Rendering button at the top-right. To return to full-frame rendering, click the Region Render button so it is no longer blue. Repeat this process with the seat_mat material. As an additional adjustment, raise the Intensity value of the window_fill light to 1.0 to bring back some of the violet color on the ground that was lost when switching to V-Ray. Test render (Figure C2.18).
Figure C2.16 Initial V-Ray render. Area
lights are rendered as solid planes.
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Figure C2.17 The trim area lights are hidden and the key area light is replaced by a V-Ray Rect light, returning the render to a state similar to the
one produced by Maya Software.
Figure C2.18 The materials assigned
to the tires and seats are adjusted to
reduce the specular reflectivity.
Lighting a Complex Night Interior
5. Many renderers offer the means to replicate participating media in the form of environmental fog. Envi-ronmental fog is generally created by a volumetric shader that emulates the media within a 3D volume. V-Ray provides a set of volumetric shaders for this purpose. To use such a shader, you must create a fog container. To do so, create a primitive cube (Create > Polygon Primitives > Cube). Scale and translate the cube so it surrounds the garage model. For the fog to be visible in the render, the rendering camera must sit outside the cube (Figure C2.19).
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6. Assign the polygon cube to a new Lambert material (click the Lambert icon in the Create > Maya > Sur-face menu of the Hypershade window, select the cube, RMB-click over the new Lambert material in the Materials tab of the Hypershade, and choose Assign Material To Selection from the menu). Double-click the new material to open it in the Attribute Editor. Change Transparency to white so the polygon box is not seen during the render.
7. In Maya, volumetric shaders must be connected to a material’s shading group node. Shading groups are created automatically when a surface is assigned to a material. To find the correct shading group, RMB-click over the material icon in the Materials tab of the Hyperspace window and choose Graph Network from the menu. The shading network is displayed in the work area. A SG (Shading Group) node is connect-ed to the material. Double-click the SG node to open it in the Attribute Editor. Click the checkered map button beside the Volume Material attribute. The Create Render Node window opens. Navigate to the Create > VRay > Volumetric section and click the VRay Environment Fog icon. A VRayEnvironmentFog1 shader is added to the scene. Test render. Fog appears but is so opaque that the garage is not visible.
8. To adjust the fog density, double-click the VRayEnvironmentFog1 icon in the Materials tab. In the Attri-bute Editor, set Fog Distance to 250. Fog Distance sets the fog density. Small values create a more opaque fog while larger values create a more transparent fog. For this scene, we want to make the fog relatively subtle. Change the Color to white and Emission to dark gray. Although the fog color is influenced by the color of lights in the scene, you can brighten the fog by raising these attribute values. The Emission attributes makes the fog self-illuminated. You can further adjust the self-illumination by adjusting the Emission Multiplier. Test render. The fog becomes more subtle (Figure C2.20). Note that the primitive helix used as a light flag casts a shadow into the fog. Hence, it may be necessary to adjust the helix translation and rotation. For example, move the helix farther away from the VRayKey light.
9. Thus far, we have not employed GI to calculate light bounce in the form of indirect illumination. You can activate indirect illumination when using V-Ray by going to the Render Settings window, switching to the GI tab, and selecting the On checkbox. You can make the environmental fog a part of the GI calculation by going to the VRayEnvironmentFog1 shader’s GI section and selecting the Scatter GI checkbox. Test render. The use of GI brightens the cyan wall trim as the incandescence is considered a light source. The cyan light also appears brighter along the floor. GI also affects the upper portions of the wheels, where bounce light from the floor reaches the tops of the rims. At this stage, a large amount of noise is apparent in the render; we’ll adjust the render quality settings at the last step to remove this.
Figure C2.19 A primitive polygon cube is scaled
to surround the garage and will serve as an
environmental fog container. The rendering
camera, seen as a green icon, is left outside
the cube.
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Figure C2.20 Environmental fog is added to the scene. The fog appears the most dense at the back corner of the room and most
intense under the ceiling key light. The overall contrast of the render is reduced by the presence of fog. The rotation of the helix
light flag is adjusted; its shadow appears within the fog below the key light.
Figure C2.21 GI is activated, creating light bounce. As a result, the cyan wall trim appears to glow.
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10. V-Ray environmental fog reacts to lights placed within its volume. Hence, you can form beams of light. For example, we can create headlight beams for the vehicle. To do so, create a new spot light (Create > Lights > Spot Light). Rename the new light headlight. Translate, rotate, and scale the new light so that it protrudes from one of the vehicle’s headlight squares (Figure C2.22). Open the light’s Attribute Editor tab. Turn off shadows by deselecting Use Ray Trace Shadows. If the light is not casting shadows, you are free to let the light intersect the vehicle and floor geometry. Set the light’s Cone Angle to 5 and Penumbra Angle to 15. Set the Decay Rate to Linear and Intensity to 350. Test render. A light beam appears in the fog. Feel free to adjust the light Intensity to make the beam brighter or darker. When you are satisfied with the adjustments, duplicate the light and position the copy in front of the remaining headlight. Test render (Figure C2.23)
Figure C2.22 Two Maya spot lights are
placed in front of the vehicle to form
headlight beams. The lights illuminate the
environment fog so long as they are within
the fog container.
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Figure C2.23 The resulting headlight beams. The floor is illuminated where the spotlights intersect the floor geometry. A large Penumbra
Angle value on each light ensures a soft edge to the light throw.
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11. As a final step, we can improve the render quality and remove noise that is present in a number of areas. (The noise is the heaviest along the top of the vehicle, within the white headlight beams, and directly below the yellow ceiling light.) This requires the adjustment of V-Ray sampling. Open the Render Settings window. Switch to the VRay tab. By default, V-Ray uses the progressive style of sampling, where the entire render is progressively sampled and the render image is gradually refined. This approach is suitable for testing. You can improve the result of this style of rendering by increasing the Min Subdivs and Max Subdivs attribute values. These values set the degree of subpixel sampling. For example, you can set Min Subdiv to 16 and Max Subdiv to 128. Higher values will slow the render significantly but will improve the resulting quality. Another approach requires the use of adaptive sampling where additional subpixel sam-pling occurs where there is the highest contrast between neighboring pixels. To switch to this approach, change the Sampler Type menu to Bucket. With this setting, it’s not necessary to increase the Min Subdivs and Max Subdivs values unless the render contains thin lines or heavy motion blur. Sampler Type, Min Subdvis, and Max Subdivs attributes are located in the Image Sampler section near the top of the VRay tab.
A final render is illustrated by Figure C2.24. The final Maya Software scene is included in the \Proj-ect-Files\Maya\ directory as Garage-Maya-Final.ma. The final V-Ray scene is included in the \Project-Files\Maya\ directory as Garage-Vray-Final.ma.
Figure C2.24 The final render.
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Case Study 3: Lighting anAnimated Animal Character
With this case study, we’ll light an animated character. As opposed to working with a human character, we’ll apply the lighting to a fox (Figure C3.1). A fox shares many of the same facial features as a human (eyes, nose, cheeks) and can be lit with many of the techniques discussed in earlier chapters. Other unique mammalian features, such as large ears and a four-legged stance, will present new challenges. Exercise steps are outlined for Autodesk Maya but can also serve as a general guideline for other 3D programs. The fox model was created by Daniel Moos and is licensed via Creative Commons Attribution 4.0 International (CC BY 4.0).
In addition to possessing an animated character, the scene includes an animated camera. This requires that the resulting lighting appear attractive from multiple points-of-view. The animation is 72 frames in length. Figure C3.2 shows the fox and camera positions for frame 1 and frame 72.
Figure C3.1 The fox model.
Figure C3.2 Left: Frame 1 of the animation. Right: Frame 72 of the animation. Rendering camera is indicated by the green icon.
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We’ll begin the exercise by answering important lighting questions introduced in Chapter 3:
What is the context of the lighting? We are lighting a single shot, so it does not need to match any particular source.
What is the location of the lighting? Exterior.
What is the time of day? We’ll assume it is daytime, either late morning or early afternoon.
What are the properties of the light sources? We will light naturalistically. Although the fox and the landscape is not strictly realistic, we’ll approach the lighting in a realistic fashion. The lights include:
A) The sun as a key light.
B) Bounced sun light as fill.
Using Autodesk Maya with the Maya Software Renderer
1. Launch Autodesk Maya. Open the Fox-Start.ma file from the \Project-Files\Maya\ directory. Take a few minutes to familiarize yourself with the scene contents. The scene contains the rigged and an-imated fox model, an animated camera named renderCamera, and a partial landscape. A second camera, named persp, is left as a work camera and is not intended for rendering. If you are not using Maya, a Fox-Start.fbx file is saved to the same the same directory (the FBX version swaps out the character rig for static versions of the fox).
2. Select the renderCamera viewport and play back the timeline to examine the animation. Note that the camera moves in such a way that both sides of the fox are visible at various points (Figure C3.3). It will be necessary to position the key light so that the lighting on the fox remains attractive throughout the timeline.
3. Create a directional light (Create > Lights > Directional Light). Scale the light icon up so it’s easier to see. Position the light in front of the geometry (the exact translation does not matter). Rotate the light so it points down 45 degrees. For example, rotate the light to –45, 0, 0. Through the renderCamera viewport menu, choose Lighting > Use All Lights and Lighting > Shadows. Do the same with the persp viewport. The directional light’s illumination and shadows appear in the viewports. With recent versions of Maya, ray trace shadows are automatically activated for directional lights.
Figure C3.3 Left: Frame 35, as seen by the renderCamera. Right: Frame 72. Both sides of the fox are seen in a single shot.
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4. Experiment with light rotation to see how the fox is lit and how the shadows form. For example, if the light is left at –45, 0, 0, neither side of the fox is fully lit; in addition, long shadows form behind the fox’s ears. If the light is rotated to –45, 15, –15, a shadow from a nearby cactus crosses the fox and the end of the timeline (Figure C3.4). If the light is rotated to –45, 0, 45, the fox screen-left side is sufficiently lit while the opposite side receives no light. When testing each light rotation, play back the timeline to see how the lighting looks at different frames (Figure C3.5). With this scene, a light rotation of –45, 0, 45 produces the best result.
Figure C3.4 Top: Directional light rotated to –45, 0,
0, as seen through the persp camera. Middle: Light
rotated to –45, 15, –15. Bottom: Light rotated to –45,
0, 45.
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Figure C3.5 Top: Directional light rotated to –45, 0, 0, as seen through renderCamera on frame 72.
Middle: Light rotated to –45, 15, –15, which throws a cactus shadow over the fox. Bottom: Light rotated
to –45, 0, 45, creating an mammalian variation of Rembrandt lighting. Short lighting is also created as
the side of the face pointed away from the camera receives the key light.
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5. Open the Render Settings window. Set the Render Using menu to Maya Software. Go to the Maya Software tab. Set the Edge Anti-aliasing menu to High Quality. This will improve the edge quality of the render while slowing the renderer slightly. Expand the Raytracing Quality section. Select the Raytracing checkbox. This is necessary to render ray trace shadows. Although the Maya Software renderer is a basic renderer with few PBR functions, it is suitable for roughing in the lighting. Using the Render View (Win-dows > Rendering Editors > Render View), test render several frames (Figure C3.6). Adjust the directional light Intensity to mimic the intensity of sun light. An Intensity of 2 works well with the materials and tex-tures provided for the fox and landscape. Set the light color to a desaturated blue (0.9, 0.975, 1.0 in RGB); this roughly replicates the blue wavelength of daytime sunlight. Note that the sky color is provided by the Background Color of renderCamera. If you are using a version of Maya that includes a View Transform button in the Render View window, turn the button off to properly judge the lighting; if the button is left on, an additional gamma adjustment is applied to the render (see Case Study 1 for more information).
6. Duplicate the directional light by selecting it and choosing Edit > Duplicate. The duplicated light remains selected. Move the new light away from the original light. Change the name of the new light to fill. Change the name of the original light to key. Rotate the fill light to illuminate the dark side of the fox. The light should arrive from below as if bouncing off the ground (Figure C3.7). This leads to the ground geometry casting a shadow onto the fox, rocks, and cacti, which defeats the purpose of the fill light. To avoid this, select the ground geometry (named ground), go to the groundShape tab in the Attribute Editor, expand the Render Stats section, and deselect Cast Shadows. The fill light thus ignores the ground and reaches the fox. Adjust the fill light Intensity. Test the light on different frames of the animation. It’s common for a fill light to only have 25% to 50% of the Intensity value of the key light. In this case, an Intensity value of 0.5 is suitable. This creates a 4:1 lighting ratio. Because the fill light is copied, it maintains a pale blue color.
Figure C3.6 Left: Frame 1 rendered with the Render View. Right: Frame 72.
Figure C3.7 Left: The fill light is given a rotation of -40, 60, -60. The ground geometry is prevented from casting shadows. Right: Resulting render
when fill light is given an Intensity of 0.5.
FillKey
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7. The current light rotations create a core along the top of the fox and rocks (Figure C3.8). When discussing light patterns, a core is the darkest part of the surface where lights overlap but have the least strength. Cores occur naturally. However, if a core is too dark, it will not match the daylight setting. Duplicate the key light by selecting it and choosing Edit > Duplicate. The duplicated light remains selected. Move the new light away from the original light. Change the name of the new light to core. Rotate the core light to point down so it illuminates the core areas. For example, rotate the light –50, 24, 20. This creates an overlapping shadow, which does not fit a daytime exterior. Deactivate ray trace shadows for the core light by deselecting Use Ray Trace Shadows in the light’s Raytrace Shadow Attributes section. Set the core light Intensity to 0.3. To avoid overexposure of the ground, reduce the Intensity of the key light to 1.7. Test ren-der. The core light fills the core area. In addition, it allows ground detail to be seen within the key light’s cast shadows, which would otherwise remain black (Figure C3.9). The inside of the mouth also receives light.
Figure C3.8 Close-up of render. Arrows indicate
core area that forms along the fox’s back.
Figure C3.9 Render after the addition of the core light. Note the detail now visible within the cast shadow.
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8. At this stage, the key and fill lights are casting ray trace shadows. Although ray trace shadows have their strengths, they also have limitations. For example, with a low-resolution model such as the fox, ray trace shadows can create shadow artifacts. The artifacts appear as faceting where the shadow suddenly changes in brightness along polygon edges. This is visible along the fox’s nose, muzzle, and interior ears in Figure C3.8. One solution is to switch to depth map shadows. To do so, select the key light, expand the Depth Map Shadow Attributes section within the Attribute Editor, and select Use Depth Map Shadows. Selecting this checkbox automatically disables ray trace shadows. Set the Resolution attribute to 4096. Because the 3D scene is expansive, with the fox at a much smaller scale than the ground, it’s necessary to use a large depth map resolution. If the resolution is too small, the pixels within the depth map will be visible as stairstepped and pixelated shadow edges. Repeat this process with the fill light. However, set the fill light’s Resolution to 2048 and Filter Size to 12. Using a large Filter Size value adds an additional blur to the shadow edge. A shadow is useful for the fill light as it prevents the fill from reaching areas that bounced light would not normally reach; however, a hard-edged shadow does not match the quality of bounced light. Test render across multiple frames (Figure C3.10).
9. Depth map shadows, much like ray trace shadows, suffer from their own form of artifacts. Th artifacts may appear as a general noise or small, dark triangles. The artifacts may occur along curved surfaces where the program is confused by the position of the shaded surface in comparison to the showing-casting light. For example, if you look closely at frame 60, artifacts appear along the ears (Figure C3.11). In addition, it’s still possible to see stairstepping caused by an insufficiently large depth map resolution.
Figure C3.10 Clockwise, from top left: Frame 12, 44, 56, and 72 with depth map shadows.
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10. To remove or reduce depth map artifacts, you can adjust the Bias attribute that is located in the Depth Map Shadows Attributes section of the key light’s Attribute Editor tab. Slowly raise the Bias value and test render. Bias offsets the positional value of the shadowed surface, pushing surface points in or out of shadow. (Other 3D programs that use depth map shadows will have equivalent attributes that carry out the same function.) For example, set the Bias value to 0.005, test render, set the Bias to 0.01, test render, and so on. When the artifacts are sufficiently reduced or disappear, the Bias value is acceptable. Note that changes in Bias value can have detrimental effects on other portions of the frame. For example, high Bias values may disconnect cast shadows so that there is a gap between the shadow-casting object and the shadowed surface. For example, if Bias is set to 1.0, the cast shadow of the fox on the ground is disconnected from the fox’s feet. A better value for this scene is 0.05. This reduces the artifacts but does not remove them completely. To further reduce the impact of the artifacts, you can raise the Filter Size, which blurs the edges of the resulting shadows. Raising the Filter Size of the key light to 3 helps reduce the visibility of the artifacts (Figure C3.12). In addition, a higher Filter Size disguises the resolution limits of the depth map by blurring the stairstepping. Although some artifacts remain, these are a product of the low-resolution geometry; any remaining artifacts will be difficult to see when the fox is in motion.
Figure C3.11 Close-up of frame 60. Depth map rendering artifacts appear on the frame-left ear. In
addition, stairstepping from insufficient depth map resolution is apparent on the frame-right ear.
Figure C3.12 Frame 60 after adjustment of the key
light’s Bias and Filter Size attributes.
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Switching to the Arnold Renderer and Adding a Sky Shader
1. Recent versions of Maya (2017 and later) make the Arnold renderer the default renderer. Hence, it’s worth seeing how Arnold differs from Maya Software renderer. If you have access to Arnold, switch the Render Using menu in the Render Settings window to Arnold Renderer. Test render a frame (Figure C3.13). You’ll notice immediate differences:
• Although Arnold understands standard Maya materials, it treats each material that possesses specu-larity as if it is reflective. Hence, the ground subtly reflects the cacti and rocks.
• The reflectivity of the materials that possess specularity becomes more accurate. The reflections are path traced. Hence, the fox’s eyes reflect the various light sources with more intensity.
• Arnold applies linear light decay to directional lights. Hence, the lighting becomes dimmer.• The Bias and Filter Size attributes affecting the depth map shadows are ignored. Arnold supplies its
own shadow settings. At the same time, shadows appear for all the lights.• The blue sky color provided by the Background Color attribute of the renderCamera is ignored.• Maya standard material bump mapping is not supported by Arnold.
2. Select the key light and go to the Attribute Editor. Raise the Intensity value and test render on different frames. A value of 5 creates a brightness equivalent to the Maya Software renderer. Go to the Arnold section and expand it. To soften the shadow slightly, raise the Angle attribute, which controls the virtual width of the light. For example, set Angle to 1.0. Set Samples to 6 to refine the edge quality. Select the fill light and go to the Attribute Editor. Set the Intensity to 1.25. This maintains a 4:1 lighting ratio. In the Arnold section, set Angle to 6 and Samples to 6. Select the core light. Set Intensity to 0.5. In the Arnold section, deselect Cast Shadows. Test render (Figure C3.14). The path tracing nature of Arnold adds addi-tional bounced light along the belly and legs of the fox.
Figure C3.13 Frame 72 after the switch to the Arnold renderer.
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3. To match the materials to the Maya Software render, we will have to adjust materials within the Hyper-shade window. Although texturing is not necessarily a part of 3D lighting or the domain of a lighter, it’s often useful to make shader adjustments (assuming it’s a permitted step on a production). Choose Windows > Rendering Editors > Hypershade. Double-click the eye_mat icon. The material is a Phong. In the Attribute Editor, go to the Specular Shading section and increase the Cosine Power to 100 while reducing the Specular Color to dark gray. Test render. These steps reduce the size of the specular reflec-tions and decrease the brightness of the reflections. In the Hypershade, double-click the teeth_mat icon. This material is a Phong E. In the Specular Shading section of the Attribute Editor, set the Highlight Size to 0.05 and the Specular Color to dark gray. Repeat these steps with tongue_mat, which is also a Phong E material. Test render the fox’s face. The specular intensity is reduced for the teeth and tongues. In the Hypershade, double-click the ground_mat icon. In the Specular Shading section of the Attribute Editor, set Specular Rolloff and Specular Color to 0 or black. Do the same for the cactus_mat and rock_mat, all of which are Blinn materials. These steps prevent specular reflectivity from appearing on the ground, rocks, and cactus. Test render.
4. To add back the blue sky color, you can use an Arnold sky shader. A sky shader adds a surrounding sky color but does not add a virtual sun. To do so, open the Render Settings window. Switch to the Arnold Renderer tab. Expand the Environment section. LMB-click the map button beside the Background (Maya 2017) or Background (Legacy) (Maya 2018) attribute. Choose Create Sky Shader from the pop-up menu. An Ai Sky shader is created. In the Attribute Editor, change the shader’s Color attribute to a sky color. The example renders use an RGB value of 0.6, 0.7, 0.8 in RGB. Test render. The sky color of the sky shader is treated as a light source by the Arnold renderer. Hence, the shadow areas of the render receive additional illumination and there is less need for the fill and core directional lights (Figure C3.15). Due to the extra bounce light, you can adjust the intensities of the key, fill, and core lights. For example, reduce the key light Intensity to 4 and turn off the core and fill lights by desecting their illuminates By Default checkbox-es.
Figure C3.14 Frame 72 after the readjustment of the key, fill, and core lights. Note that the cast shadow softens over distance,
which the Maya Software renderer is unable to achieve with directional lights.
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5. As a final step, we can add back the bump map missing on the ground. This requires the use of an Arnold material. An Ai Standard material (Maya 2017) and Ai Standard Surface material (Maya 2018 and later) are included in the scene file for this purpose. Select the ground geometry, go to the Hypershade window, RMB-click over the ai_ground or ai_ground_18 material, and choose Assign Material To Selection. The materials use the same bitmap texture as a color map and a bump map as does the ground_mat Blinn material. The Ai materials treat a bump map in a similar fashion as a Blinn material but require a lower Bump Depth value through the connected Bump 2D utility node. Render multiple frames to test (Figure C3.16).
Figure C3.15 Top: Frame 42. Bottom: Frame 72. An Arnold sky shader is added, providing additional fill light to the unlit areas of
the frame. The fill and core directional lights are deactivated. Hence, the scene is lit only by the key light. The path tracing nature
of Arnold adds extra illumination as bounce light. In addition, the specular intensity and reflectivity of various surfaces has been
reduced by adjusting the specular attributes of the assigned Blinn, Phong, and Phong E materials.
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Figure C3.16 Top to bottom: Frames 15, 55, and 72 of final render with restoration of ground bump map (as seen
in Maya 2017).
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The lighting is now complete in the scene. Because this scene features an animated sequence, we can take additional steps beyond this point:
Quality Settings Test render to determine the best quality settings. When using Maya Software you can adjust the attributes of the Anti-aliasing Quality section of the Maya Software tab of the Render Settings window. When using the Arnold renderer, you can adjust the attributes within the Sampling section of the Arnold Renderer tab of the Render Settings window. Although the final sample files include render quality settings sufficient to produce the figures for this book, you are free to make ad-justments. For example, it may be necessary to reduce the render quality to speed up the test renders or increase the render quality to avoid anti-aliasing issues on the bumpy ground.
Add Motion Blur When you have motion, you can activate motion blur. When using Maya Software and Arnold renderers, you can activate motion blur through their respective Motion Blur sections within the Render Settings window.
Render the Animation Batch render the scene as an image sequence or movie. Upon viewing the fully-rendered version, it may be necessary to further fine-tune the render quality or shadow attributes.
Change the Resolution Although the scene files included in this book are set to a 1280×720 resolu-tion, you are free to change the resolution. Different output destinations, such as broadcast television or web streaming, require different resolutions. Each resolution may require slightly different render quality settings to produce acceptable results. For example, bump maps may render differently with different resolutions where smaller resolutions require more aggressive anti-aliasing settings.
One disadvantage of using the Arnold sky shader is the presence of excess fill light within the cast shadow on the ground. Hence, any given renderer offers its own set of advantages, disadvantages, and unique traits. The final Maya Software scene is included as Fox-Maya-Final.ma in the \Project-Files\Maya\ directory. The final Arnold scene is included as Fox-Arnold-Final.ma in the \Project-Files\Maya\ directory.
Lighting an Animated Animal Character
Creating Skies in 3D
There are several ways to create a sky when working with 3D animation:
• Leave the sky empty. This causes the empty area of the frame to render black and to have transparent alpha. A new sky can then be added as part of a 2D compositing step. The new sky may be derived from a photo, video footage, or a solid color. If the camera is moving, this may require additional motion tracking in the compositing program.
• Create a sky in the 3D program by creating sky geometry, adding a sky shader or sky system supported by the renderer, or, if available, change the background color of the camera. De-pending on the method you use, this may or may not affect the alpha channel transparency.
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Epilogue: The Future of 3D Lighting
The future is sometimes difficult to imagine. Hence, old predictions often appear quaint or out-of-touch. Nev-ertheless, it’s a worthy exercise when considering your artistic career.
As I wrote this book in the summer of 2017, I was aware that 3D lighting techniques and approaches were rapidly evolving. As such, I tried to include the most important lighting fundamentals—in terms of aesthetics, basic technical underpinnings, and organized work flow. Nevertheless, you might ask “Where is it all headed?” Here are a few thoughts...
“Cover of the March 1921 issue of Popular Science magazine“, posted to
Wikimedia Commons by Google Books, is considered in the public domain.
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• PBR (Physically Based Rendering) will become the standard for rendering, whether it’s for mundane batch rendering, a real-time simulation through a video game engine, or as a part of new virtual reality vehicle. Undoubtedly, PBR approaches will become more refined and computers will become faster, mak-ing the lighting results more and more realistic with less set-up and adjustment.
• 3D tools will continue to automate the lighting process so there are fewer technical considerations for lighters. The process of testing, troubleshooting, and debugging will remain, but there will be a greater opportunity for lighters to concentrate on the aesthetic component.
• AI (Artificial Intelligence) will work its way into lighting. Already, there are rendering tools that take advantage of neural networks and adaptive algorithms to refine and optimize digital images. AI will find its way into common 3D lighting tools. The end result is a more efficient set of tools that require less guess work on the part of the lighter. For example, there will be less time spent test rendering lights and shadows to produce acceptable intensities, colors, and edge qualities.
• The basics will retain importance. No matter how advanced the lighting tools and renderers become, value will still be attached to lighters who understand lighting theory, history, and manual application.
Despite this uncertainty, I offer the following recommendations:
• Look around you. The world is full of interesting lighting scenarios, both from the natural world and the one that’s man-made. Now and then, as you’re out and about, ask yourself, “How is this lit?” or “How would I light this?”
• Look behind. History is full of great lighting examples in the form of the various arts. Generations of artists have worked hard to capture and mold light, so why not absorb some of their wisdom?
• Experiment. Don’t be afraid to try new techniques and applications. Lighting, especially with a 3D pro-gram, is fairly easy to alter. It doesn’t hurt to try a new lighting scenario or technique on occasion.
• Start with the basics. Before you activate advanced lighting systems and advanced renderers, master the basics of lighting with simple light types and default renderers. Developing a mastery of all approach-es to lighting will make your lighting work more efficient and more appropriately chosen for each project.
• Add research to your to do list. It can be difficult to keep up with all the technical developments but time spent reading up on the latest tips and tricks can pay off. Software forums, user tutorial videos, and industry conventions (such as NAB and SIGGRAPH) are good places to retrieve information in a short amount of time.
• Take it one step at a time. Even if you don’t follow the steps I’ve suggested in this book, take a me-thodical approach to your lighting. If you apply the lighting in regimented fashion, you’re more likely to understand what is actually happening when you light.
• Have fun. Lighting can be a very rewarding part of 3D.
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2017 self portrait.
Thank you for joining me on this lighting journey!
Epilogue
I would also like to remind the reader that I am completely self-taught. I will not claim to know every intricacy of lighting as it applies to the general arts and 3D animation. However, I have studied and applied lighting theory, history, and technique extensively over the last 25 years. I say this for two reasons: 1) If you take the craft seriously, you can master the finer points of lighting on your own initiative (it’s even easier these days due to the tremendous wealth of knowledge available on the Internet); 2) The learning never ends and that’s not a bad thing. Every time I light a 3D scene or paint a painting on canvas, I think of it as another step in the learning process. With this in mind, I know the next piece will turn out even better!
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“ “Change is the law of life. And those who look only to the past or present are certain to miss the future.” —John F. Kennedy
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ContentsAppendix: Visual Lighting Glossary
0-Point Lighting A style of art that does not include lighting information.
1-Point Lighting A lighting scheme that uses a single strong key light with no iden-tifiable fill light.
2-Point Lighting A lighting scheme that uses a key light and a secondary fill light.
Frame from “Felix the Cat in April Maze” cartoon (1930), determined to be in the public domain.
Copyright Alexander Cherepanov / 123RF Stock Photo.
“Cottages and a Mill on the Banks of a Stream“ (1831) by Jean-Baptiste-Camille Corot. Public domain photo
provided by The Yorck Project: 10.000 Meisterwerke der Malerei. DVD-ROM, 2002. ISBN 3936122202. Distributed by
DIRECTMEDIA Publishing GmbH.
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3-Point Lighting A lighting scheme that uses a key light, a secondary fill light, a third light, which may be a rim, hair, kicker, back, or background light.
Ambient Light A 3D light that reaches all points in a scene equally.
Area Light A 3D light bound by a shape (most often rectangular); the light operates like an array of lights that point in one direction but diverge over distance.
Back Light A light aimed at the back of the subject (opposite the camera or viewer).
Background Light A light aimed at the background behind the subject.
Bounced Light Light that has reflected off of a surface.
“300 watt key light with 150 watt back light and bounce board fill” by James Jeffrey licensed under Creative Commons Attribution
2.0 Generic (CC BY 2.0).
Copyright Alexander Eugene Sergeev / 123RF Stock Photo.
“Porträt der Antonietta Tarsis Basilico “ (1851) by Francesco Hayez. Public domain photo provided by The Yorck
Project: 10.000 Meisterwerke der Malerei. DVD-ROM, 2002. ISBN 3936122202. Distributed by DIRECTMEDIA
Publishing GmbH.
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Color Bleed The alteration of light color when light reflects off surfaces. The color of one surface “bleeds” onto the next surface.
Color Temperature The tempera-ture at which an ideal black body would emit radiation of the same color as a given object. (A black body is a theoretical material that absorbs all incident electromagnetic radiation.) Color temperature is expressed in Kelvin or K—for example, 3500 K.
Butterfly Lighting Also known as Paramount lighting, this scheme places the key high above the subject, creating a small butterfly-like shadow under the nose.
Depth Map Shadow A type of 3D shadow that creates a bitmap from the view-point of the shadow-casting light.
Diffuse In general, diffuse refers to the diffuse reflection of light off a surface due to the imperfections of the surface. A diffuse surface may have little, if any, specularity. Diffuse color is the color of a surface with no specularity. Diffuse reflections may also refer to light scatter due to refraction. Albedo, in contrast, is surface color without lighting information.
Copyright Konrad Bak / 123RF Stock Photo.
“Cornell box, rendered in POV-Ray with the provided script (by Kari Kivisalo).” by SeeSchloss licensed under Creative Commons and
is considered in the public domain.
DiffuseDiffuse+ Specular
“Comparison of a standard 60 watt (W) frosted incandescent lamp with a color temperature of approximately 2700 kelvin (K),
a 13 W 3500 K compact fluorescent lamp, and a 13 W 5500 K compact fluorescent lamp.” by Yerocus licensed under Creative
Commons and is considered in the public domain.
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Directional Light A 3D light that cre-ates parallel rays, similar to sun light reaching the Earth.
Environment Light A 3D light that creates a spherical or hemispherical array of light rays, suitable for mimicking light from a sky or surrounding location. (See IBL.)
Eye Light A light focused on the eyes of the subject.
Fill Light A non-key light that represents a weaker light source or light from the key that has reflected off surfaces.
Final Gather (GI) A form of GI (Global Illumination) and a 3D rendering system that replicates bounced light by sending out hemi-spherical clouds of secondary final gather rays to seek additional surfaces near initial surface point intersections.
Frame from “Star Trek” TV series (1966-69),© Desilu Productions. Fill
“A schema that shows how final gathering works” by Metoc~commonswiki licensed under Creative Commons Attribution-Shar-
eAlike 2.5 Generic (CC BY-SA 2.5).
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Fresnel Reflection A reflection that follows the Fresnel equations. The strength of a reflection vs. the strength of refraction (trans-mission) is dependent on the viewing angle.
Glamour Lighting A loose term for any lighting that attempts to make the subject beautiful, handsome, or otherwise unusually attractive.
Hair Light A light aimed at the subject’s hair, arriving from behind.
Hard Lighting Lighting that creates a hard-edged shadow, often produced by paral-lel light rays.
High-Key Lighting that has a low lighting ratio where there is little contrast between the key and fill.
“A woman with a rose“ by Jean-Christophe Destailleur licensed under Creative Commons Attribution-ShareAlike 3.0 Unported
(CC BY-SA 3.0).
Frame from motion picture “Lights Out” (2016),© New Line Cinema.
“Rim Of The World Rally 2004, Lancaster, California “ by IvyMike licensed under Creative Commons Attribution 2.0 Generic (CC
BY 2.0).
Frame from motion picture “Marie Antoinette” (2006),© Columbia Pictures Corporation.
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IBL (Image-Based Lighting) Lighting that uses a bitmap image to determine light intensity and color. IBL systems often use HDR (High Dynamic Range) images with special projection mappings.
Key Light The strongest light in a scene.
Kicker (Light) A utility light that adds illumination to the side of a subject (similar to a rim light).
Lighting Ratio Ratio between the brightness of the key light and fill light, ex-pressed as Key:Fill. A high-key ratio is 1:1 or 2:1 and a low-key ratio is 3:1, 4:1, and so on.
Light Ray A vector that represents the direction light travels from its source. Light rays are often represented as arrows when illustrat-ing 3D lighting and rendering systems.
Loop Lighting A lighting scheme that creates small loop-like shadow under the nose of the subject.
K:F
Kicker
Frame from motion picture “Fight Club” (1999),© Fox 2000 Pictures.
Photo of Fridtjof Nansen from the George Grantham Bain collection at the Library of Congress.
Key
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209
Low-Key Lighting that has a high lighting ratio where there is a high contrast between the key and fill.
Mesh Light A 3D light that bases its shape on user-defined geometry.
Naturalistic Lighting Any lighting scheme that attempts to faithfully recreate real-world lighting.
Path Tracing A form of global illumina-tion and ray tracing that adheres to physical-ly-based calculations.
PBR (Physically Based Render-ing) PBR may be applied to lighting systems, rendering systems, and/or shaders.
Photometric Light A 3D light that uses a photometric IES file to accurately recreate a particular light bulb and light fixture.
Photon An elementary particle that rep-resents a quantum of electromagnetic radiation produced by an electromagnetic field.
Photon Mapping A form of global illumination that traces virtual photons through a scene as they reflect and transmit.
Frame from motion picture “Hollow Triumph” (1949),© Bryan Foy Productions.
“Portrait of Cardinal Guido Bentivoglio“ (c. 1625) by Anthony van Dyck. Public domain photo provided by The
Yorck Project: 10.000 Meisterwerke der Malerei. DVD-ROM, 2002. ISBN 3936122202. Distributed by DIRECTMEDIA
Publishing GmbH.
“Illustration of BRDF (Bidirectional reflectance distribution function) and BTDF (Bidirectional transmittance distribution
function)“ by Twisp licensed under Creative Commons and is considered in the public domain.
“Global illumination illustration “ by Grzegorz Tanski licensed under Creative Commons and is considered in the public domain.
Visual Lighting Glossary
210
Point Light A 3D light that is omni-direc-tional from a point in space.
Radiosity A form of global illumination that pre-calculates reflections from each sur-face to every other surface in the 3D scene.
Ray Tracing A rendering system that traces light rays through a scene as they reflect and transmit.
Ray Trace Shadow A 3D shadow cre-ated by a ray trace renderer that uses shadow rays traced from surface points to shadow-cast-ing lights.
Refraction The transmission of light rays through a material often leading to a change in light speed at the material boundary.
Rembrandt Lighting A lighting scheme that places a triangular patch of light on one cheek. Named after the painter Rem-brandt van Rijn.
“Uniformity“ by Atoma licensed under Creative Commons Attribution 2.5 Generic (CC BY 2.5).
“Bust of a woman with a feathered beret“ (1632) assumed by Rembrandt van Rijn. Public domain photo provided
by The Yorck Project: 10.000 Meisterwerke der Malerei. DVD-ROM, 2002. ISBN 3936122202. Distributed by
DIRECTMEDIA Publishing GmbH.
“This image was created by Gilles Tran with POV-Ray 3.6 using Radiosity. The glasses, ashtray and pitcher were modeled with
Rhino and the dice with Cinema 4D“ by Gilles Tran licensed under Creative Commons and is considered in the public domain.
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211
Frame from motion picture “Hugo” (2011),© Paramount Pictures.
“Phong shading sample” by T-tus is licensed under Creative Commons and is considered in the public domain.
“Black Drongo in silhouette at dusk” by Avadesh Malik licensed under Creative Commons Attribution 3.0 Unported (CC BY 3.0).
Renderer A system that uses an algorithm to create a final output image within a 3D program. Many 3D programs offer multiple renderers, each with a different set of options.
Rim Light A light designed to illuminate the edge of a subject from behind.
Shader (Material) An algorithm that defines the qualities of a 3D surface (matte, glossy, smooth, bumpy, and so on). Shaders are often used in conjunction with procedural or bitmap texture maps.
Secondary Diffuse Illumination A diffuse reflection that contributes light to nearby surfaces. Such reflection is a critical part of PBR lighting and rendering systems. (See PBR and color bleed.)
Silhouette Lighting A lighting scheme that leaves the subject underexposed and silhouetted by a brighter background.
Sky System A 3D lighting system that replicates a surrounding sky, sometimes includ-ing a virtual sun.
Soft Lighting Lighting that creates a soft-edged shadow, often produced by artifi-cial light sources or scattered light sources with nonparallel light rays.
Copyright Anatoly Fedotov / 123RF Stock Photo.
“Diffuse reflection.PNG “ by Theresa knott licensed under Creative Commons Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0).
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Specularity The specular reflection of light. A surface that is completely diffuse produces no specular reflections. In 3D, specularity may encompass an entire set of shader properties that control the appearance of specular reflections or specular highlights. Specular highlights are approximations of spec-ular reflections.
Split Lighting A lighting scheme that places the key and fill lights on opposite sides of the subject, creating a split down the center of the subject.
Spot Light A 3D light that replicates a real-world spot light used on stage and on film and video sets. The light from a spot light di-verges from a point, filling a cone-like volume.
Stylistic Lighting Any lighting that is not naturalistic and does not attempt to recre-ate real-world lighting.
Utility Light A generic light category of that includes any non-key or non-fill light. Utility lights may have a specific function, such as rim, kicker, hair, eye, back, or background lights, or may emulate a specific light source, such as a candle, stoplight, neon light, and so on.
Frame from motion picture “Blood and Black Lace” (1964),© Emmepi Cinematografica.
“The flame of a candle projected on a table though a glass paper weight acting as a lens. The photo is a manual HDR combination
of nine photos of different exposures to get the best light and reduce noise.” by W.carter licensed under Creative Commons
Attribution-ShareAlike 4.0 International (CC BY-SA 4.0).
“Diffuse and specular reflection from a glossy surface, e.g. polished marble. The quantity illustrated is luminous intensity,
which varies according to Lambert’s cosine law for a perfect diffuse reflector.” by GianniG46 licensed under Creative Commons
Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0).
Copyright Andrey Kiselev / 123RF Stock Photo.
Appendix
2132121212112121222121221212221212222 3333333333333333
Volume Light A 3D light constrained by a volume shape where the light does not go past the volume edge.
Visual Lighting Glossary
“““ “Nothing is impossible, the word itself says ‘I’m possible’!” —Audrey Hepburn
214
215
Appendix: Common Question Index
When using a reference book such as this one, it can be difficult to find pertinent information. There are com-mon questions that every lighter must answer when lighting a scene, the answers to which may not be imme-diately obvious. Hence, I’ve added a special index that associates common lighting questions with sections of this book. The sections may not answer your question specifically; however, the sections will discuss relevant topics and offer various work flows. I hope this proves useful as you light your scene.
Lighting Approaches and StylesShould I use 3-Point Lighting? 3-Point Lighting ------------------------------------------------------------------------------------ 31What are some options when lighting a character’s face? 2-Point Lighting in Portraiture ------------------------------------------------------------------ 23How do I approach realistic lighting? Naturalistic Lighting ------------------------------------------------------------------------------- 36How can I approach non-realistic lighting? Stylistic Lighting ------------------------------------------------------------------------------------ 39 Emulating Artificial Light Sources ----------------------------------------------------------------- 81What are some examples of stylistic lighting? Generating a Mood ---------------------------------------------------------------------------------- 134 Creating a Tribute to Other Art Forms ---------------------------------------------------------- 134 Creating a Visually Unconventional Look ------------------------------------------------------- 138 Establishing a Parallel World or Timeline ------------------------------------------------------ 140
Adding and Adjusting LightsIs there any order I should add lights to a scene? 3D Lighting Pipelines and Workflow -------------------------------------------------------- 42 3D Lighting Steps ---------------------------------------------------------------------------------- 46How do I figure out where to place lights? Light Sources and Location ----------------------------------------------------------------------- 3 Using Autodesk Maya with the V-Ray Renderer -------------------------------------------- 148Do 3D lights have advantages or disadvantages over each other? Common 3D Light Types ------------------------------------------------------------------------- 50
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Appendix
Adding and Adjusting LightsAre there special light types that are more accurate than others? Area Light -------------------------------------------------------------------------------------------- 52 Specialized 3D Light Types ---------------------------------------------------------------------- 59How do I choose a 3D light type when lighting something that should look real? Emulating Natural Light Sources ------------------------------------------------------------------ 72How do I choose a light color? Time of Day -------------------------------------------------------------------------------------------- 2 Wavelength, Color, and Temperature ----------------------------------------------------------- 6How do I know what light values to choose? Sidebar: Determining Values -------------------------------------------------------------------- 164How strong should the fill light be in comparison to the key light? High- and Low-key Lighting ---------------------------------------------------------------------- 27Should I use light decay? Sidebar: Using Light Decay ------------------------------------------------------------------------ 53
ShadowsWhat kind of shadow should I use? Sidebar: Light Shadowing -------------------------------------------------------------------------- 5 Shadow Variations Among Lights -------------------------------------------------------------- 56What should the edge of my shadow look like? Sidebar: Hard and Soft Lighting ------------------------------------------------------------------ 29Should I use depth map or ray trace shadows? Shadow Approaches ------------------------------------------------------------------------------ 58Can I tell a light or shadow to ignore a surface? Sidebar: Selective Shadow Casting -------------------------------------------------------------- 84 Sidebar: Light and Shadow Linking -------------------------------------------------------------- 93How do I fix shadow artifacts? Using Autodesk Maya with the Maya Software Renderer ------------------------------ 186
Shaders, Materials, and TexturesMy textures are missing—where did they go? Sidebar: Source Models and Textures ------------------------------------------------------------ 72 Sidebar: Reloading Missing Texture Bitmaps ------------------------------------------------- 148As a lighter, should I worry about shaders or materials? 3D Light Interaction with Shaders ------------------------------------------------------------- 62Do I need a refraction with a transparent surface? Reflection, Refraction, and Absorption -------------------------------------------------------- 7
2116
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Common Question Index
Shaders, Materials, and TexturesHow do I control reflections and refractions? 3D Light Interaction with Shaders ------------------------------------------------------------- 62 Common Shader Properties ----------------------------------------------------------------------65 Creating a Window Reflection ----------------------------------------------------------------- 159Can you make a surface emit light? Specialized 3D Light Types ---------------------------------------------------------------------- 59
RenderingDo I need to use color calibration or a linear workflow? Sidebar: Working with Color Calibration ------------------------------------------------------- 49 Sidebar: Gamma-Corrected Views ------------------------------------------------------------ 150Do I need to ray trace? Ray Tracing ------------------------------------------------------------------------------------------- 97Do I need to use PBR (Physically Based Rendering)? Choosing PBR --------------------------------------------------------------------------------------- 96 Overview of PBR Systems ------------------------------------------------------------------------ 98What is the difference between final gather, photon mapping, and radiosity? Photon Mapping ---------------------------------------------------------------------------------- 100 Final Gather ---------------------------------------------------------------------------------------- 102 Radiosity -------------------------------------------------------------------------------------------- 102Should I use path tracing? Path Tracing / Monte Carlo Ray Tracing ---------------------------------------------------- 103When would I use an HDR (High-Dynamic Range) image? IBL ----------------------------------------------------------------------------------------------------- 106Should I use an unbiased or biased renderer? Sidebar: Unbiased vs. Biased Rendering ------------------------------------------------------- 109Are render passes / AOVs necessary? An Introduction to Render Passes / AOVs -------------------------------------------------- 109 Sidebar: Lighting Render Passes ---------------------------------------------------------------- 111How does motion blur work? Sidebar: Motion Blur and Other Post-Process Effects --------------------------------------- 145How do I remove fireflies (rendering artifacts)? Using Autodesk Maya with the V-Ray Renderer ------------------------------------------ 148
Special SystemsHow do I add fog and glow to a scene? Switching to the V-Ray Renderer and Adding Fog --------------------------------------- 177How do I add a sky system or sky shader to a scene? Specialized 3D Light Types ---------------------------------------------------------------------- 59 Switching to the Arnold Renderer and Adding a Sky Shader ------------------------- 193 Sidebar: Creating Skies in 3D -------------------------------------------------------------------- 197
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ContentsIndex
0-point lighting: historical art 16; visual glossary 2031-point lighting: defined 19; examples of use 77, 85, 87, 91-92; visual glossary 2032-point lighting: case study 142; defined 22-23; examples of use 44, 73, 75-76, 79, 82, 88, 116, 120, 122; visual glossary 2033-point lighting: defined 31-34; visual glossary 2033/4 lighting 25
Aabsorption: light interaction 7; ray tracing 97, 99aesthetic: light xi; stylization 9, 11, 15, 39albedo: shader property 65, 99; render pass 110ambient light: described 52; examples of use 74-76, 78, 80, 83, 104, 117, 122; visual glossary 203angle of incidence 8animatic 42anisotropic 64-65anti-aliasing (render consideration) 158, 169, 197Anti-aliasing Quality (attribute) 197AO (Ambient Occlusion): PBR 99; render pass112AOV (Arbitrary Output Variable) 110area light: case studies149-151, 154, 160, 163, 168- 171, 175, 178, 181; described 52-53; examples of use 74-76, 79-81, 85-87, 93, 101, 104-105, 117-119; shadows 57; visual glossary 203Arnold (renderer): case studies154-159, 161-162, 178, 182, 193-195, 197; described 109; path tracing 104; shader variations 65; shadow variations 59; supported lights 61 artifacts (rendering) 158-159artifacts (shadow)191-192
Bback light: described 16; examples of use 26, 135; visual glossary 203
background light: case studies 140, 155, 156, 163; described 16; with 3-point 33; with silhouette lighting 34; visual glossary 203Background Color (attribute) 189, 197backlighting (See translucence)batch rendering 48, 197Bias (attribute) 192-193, 219biased (renderer) 110black body radiator 7Blinn (shader): case studies 157, 164, 194-195; described 62-63 bounce light: defined 16; examples of use 93, 96, 100- 101,105, 117BRDF (Bidirectional Reflectance Distribution Function) 64-65, 67, 98, 100, 209broad lighting 27bump map: case study 195-196; described 68-69 bump mapping: case studies 155, 178, 182, 193; PBR 99; shader property 68 butterfly lighting: described 26; visual glossary 205
Ccatch light 35caustics: case study 155; described 100; path tracing 104color bleed: case study 178; final gather 102; described 8; example 33; PBR 59, 96; photon mapping 100; visual glossary 205color calibration 49color space: described 49; linear 99color temperature: defined 7; examples of use 83, 139; light property 55; visual glossary 205cone angle: case studies 152, 181; common light property 51, 55; example 141; shadows 57 conservation of energy (BRDF) 64, 98Cook-Torrance (shader) 63, 65core (shadows) 153-154core (light pattern) 190cylindrical light 60
220
Index
DDensity (attribute) 179, 181depth map: case study 191-193; described 58-59; examples of use 73, 77, 82-83, 85, 88, 90, 92-93, 97; 117, 124; ray tracing 67; visual glossary 205render passes 111depth-of-field: post-process 145; with render pass 111 diffuse: color property 62-63; shader property 65; light property 55; light quality 78diffuse reflectivity 66secondary diffuse illumination 100directional light: described 52; examples of use 73-77, 88, 107, 117, 141; case studies 151-152, 154, 168-170, 186-189; visual glossary 206displacement mapping 68
EEccentricity (attribute) 164electromagnetic radiation: light 6-7; light decay 53Emit Specular (attribute): case study 158-159; described 55; example of use 90 emissive (see incandescence)environment light: described 60; visual glossary 206equirectangular (mapping) 107eye light: described 35; visual glossary 206
Ffill light: case studies 151-152, 154, 156, 158-159, 168,189, 193-195, 197, 203-204; described 16; examples of use 74-75, 79-80, 82-84, 90-92, 106, 117, 119, 124; historical art examples 22-25, 27-28, 31-32, 45-47, 134- 135; visual glossary 206Filter Size (attribute): case studies 163, 191-193; described 58; example 85final gather: case study 178; described 102-103; environment light 60; examples of use 119, 121-122; sky systems 108-109; visual glossary 206final gathering (see final gather)fireflies (artifacts) 158-159focal point: defined 10; examples 12, 130fog: case study 177, 179-182; post-process effect 145; shadows 56; volume lights 61, 87; with render pass 11frequency 7
Fresnel (shader) 63-64Fresnel reflection: definition 63; visual glossary 207
Ggamma: color calibration 49; case study 169; linear calculations 99; Maya Render View 149GI (Global Illumination): case study 161; described 100-104; examples of use 119, 121; sky systems 108-109; visual glossary 206glamour lighting: butterfly lighting 26; defined 21; visual glossary 207glossiness: case study 160; shader property 66; PBR 99glow: case study 179-182; defined 145; example 85-86Glow Intensity (attribute) 179, 181
Hhair light: described 16; butterfly lighting 26; visual glossary 207halation 145hard lighting: described 29; example of use 73; visual glossary 207hard-edged (shadow): 3D lights 57, 73; case studies 168, 175, 191; examples of use 44, 73 HDR (High-Dynamic Range) 106high-key: defined 27-28; visual glossary 207
IIBL (Image-Based Lighting): environment light 60; example 121; GI 106-107; visual glossary 202Illuminates By Default (attribute) 194incandescence: case study 170, 182; examples of use 82, 85-86, 143-144; shader property 68indirect illumination 100intensity (light quality): broad lighting 27; lighting determination 44; naturalistic lighting 38 intensity (3d light attribute): case studies 149-152, 154-156, 160, 163-164, 168, 170-171, 173- 175, 177-179, 181-182, 189-190, 193-195; examples of use 75-81, 83-84, 87-92, 101- 104, 106-108, 117, 119, 122, 124, 139; light property 55; lighting steps 46-47; specialty lights 60-61intersurface reflections 100irradiance cache 104isotropic 64-65
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Index
Kkelvin (K): defined 6-7; light color 55key light: case studies 148-149, 151, 154-156, 160, 163, 168, 170, 174, 186, 189-193, 195; described 16; historical art examples19, 22- 27, 32, 34-35, 45-47; 73, 82, 85, 88, 90, 124, 134-135, 141; visual glossary 208kicker (light): described 35; visual glossary 204
LLambert (shader): case study 164; described 62; properties 65 lat/long (mapping) 107layered (shader) 65light 2, 6Light Angle (attribute) 154, 168light decay: case studies 150, 172, 173; defined 53- 55; examples of use 74, 77, 79-80, 87-88, 91-93, 117, 141; photometric light 61 light flag 175light linking 93light map 65light painting: 3D example 143-144; illustrated 13 light ray: defined 7-8; PBR 100; shader functionality 63-64, 66-67; visual glossary 208light wave 6lighting ratio: defined 27-28; visual glossary 209lighting render pass 113linear calculations 99linear color space 99, 219linear (light decay): defined 53; examples of use 77 80, 104,141loop lighting: described 25; examples of use 47, 89; visual glossary 208low-key: defined 27-28; historical art example 134- 135; visual glossary 209
MMacGuffin 10material (See shader) material interface 67matte (render pass) 112matte (surface quality) 62Maya Software (renderer) 149, 168-169, 178- 180, 186, 189, 193-194, 197mesh (light): described 59-60; examples of use 82, 85, 137metal (shader property) 66
metallic specularity (PBR) 98-99microfacets: described: 63-64; PBR 100monolithic (shader) 65Monte Carlo ray tracing 104mood: defined 4; examples of use 4; lighting goal 9motion blur: path tracing 104; render pass 112; light painting 143-145; animation 197
Nnanometer 6naturalistic lighting: defined 16; historical art examples 36normal (See surface normal)normal mapping 68
OOutliner (Maya window) 157, 169Oren-Nayer (shader) 62overexposure (light intensity) 46-47
Pparallax mapping (see displacement mapping)participating media: defined 56; glow 85; volumetric lighting 61Paramount lighting (see butterfly lighting)path tracing: case studies154-155, 158, 178, 194-195; described 104-106; visual glossary 209PBR (Physically-Based Rendering): albedo 65; options 74, 96; shadows 59; systems100-101, 103- 105, 107, 109; visual glossary 209PBS (Physically-Based Shader) 99penumbra (light property): case study 152; described 55; example of use 47, 92; spot light 50-51 Phong (shader): case study 194-195; described 62- 63; properties 65photometric (light): described 61; example of use 92; visual glossary 209photon: defined 6; 3D tracing 59 photon mapping: described 100-103; example of use 124-125; visual glossary 209Physical Sun & Sky (mental ray system) 108, 121pipeline 42point cloud (GI) 103point light: case studies 163, 171, 1673; described 51; examples of use 77, 82-84, 87, 92, 101, 104, 141, 144; properties 55; shadowing 30, 57;
222
Index
visual glossary 210point-of-view 4pool light 35post-process: described 139; examples of use 144, 180Primary Visibility (attribute) 149, 175
Qquadratic (light decay): case studies 150, 155, 163, 168, 170-171, 173, 177-178, 193; defined 53; examples of use 60, 77, 79, 83, 88, 91, 93, 117, 139
Rradiosity: described 103-104; visual glossary 210ray trace: shader properties 67; shadows 57-59ray tracing (rendering system): case studies 149, 162, 168-169, 171, 177, 186, 189-191; described 97-98; examples of use 73, 76, 79-80, 82-83, 95, 97-98, 100, 104, 111, 117-119reflection: case studies149, 158, 160-161, 163, 171; IBL107; light ray 7-8; shader function 63; shader properties 66reflectivity 66refraction: case studies 171, 205; defined 8; PBR 100; ray tracing 98; render pass 110; shader function 63; shader properties 66; visual glossary 210refractive index: defined 8; shader properties 66-67refractivity 66Rembrandt lighting: described 23-24; examples of use 28, 31, 90, 188; visual glossary 210render passes 110-112Render Settings (Maya window) 158-159, 161, 169, 178-179, 189, 193-194, 197Render Using (attribute) 75, 155, 169, 178, 193Render View (Maya window) 149-150, 169, 189renderer transform 55rendering (See test rendering)resolution (render) 48, 197resolution (depth map): case studies 162, 191-192; described 58; examples of use 85, 88 rim light: described 10; 3-point lighting 31-33; kicker variation 35; stylistic 139; visual glossary 211
SSamples (Arnold renderer) 156, 158, 193scanline (rendering system) 96-97
Secondary Diffuse Scale (attribute) 122self-shadowing: bump mapping 68; defined 17; render passes 110shader: case studies 164, 193-195, 197; common properties 65-69; defined 62; examples of use 72-73, 76-77, 82, 85-86, 92; PBR/PBS 99; types 62-65; visual glossary 211shadow: case studies 151, 154-156, 161-163, 165, 168-172, 175-178, 182, 187-194, 197; defined 5; displacement mapping 69; examples of use 2-73, 75-78, 82-85, 88-93, 96-98, 103, 106, 111, 115, 117-118, 123- 124, 136, 139; historical art examples 20, 22-26, 29-30, 41, 44-45, 47; light types 50; shader function 65; time of day 2-3; variations 56-59 shadow casting 84shadow linking 93shadow rays (ray tracing) 58shadow rays (attribute) 154, 162, 176short lighting 27sight 2silhouette lighting: described 34; example 128; visual glossary 211sky shader 193-195sky system: described 108, 197; examples of use 121- 122; visual glossary 211slash light 35soft lighting: described 29; visual glossary 211soft-edged (shadow): case study 175; examples of use 44, 77, 79, 82; lighting 29; shadow quality 57; visual glossary 211specular highlights 63specular reflectivity 66Specular Roll Off (attribute) 164specularity: case studies 157, 193; examples of use 90, 92, 98-100, 110; shader function 62-63; shader property 66; visual glossary 212split lighting: described 25; historical art examples 28, 45; visual glossary 212spot light: case studies 158-161, 169, 187; described 50-51; examples of use 47, 74, 83, 92, 104, 148; light fog 56; properties 55; shadows 56-57; visual glossary 218SSS (Sub-Surface Scattering) 65stop (photography) 131stylistic: defined 4; examples of use 135, 137, 141- 143, 145; historical art examples 19-21, 29, 31, 35; lighting 11, 16; planning 134; visual glossary 212surface normal: described 7; Fresnel reflections 63-64; refractivity 67
223
Index
Ttest rendering 48texture: described 69; connecting 72, 142, 195; PBR 99texturing 49time of day 2translucence: defined 65; shader property 68transmission: defined 7; PBR 98; shader function 63; shader property 66; transparency: scanline 97; shader property 66; ray tracing 98
Uunbiased (renderer) 116Use All Lights (menu option) 149, 168, 186Use Depth Map Shadows (attribute) 191-192Use Ray Trace Shadows (attribute) 67, 82, 149, 190utility light: case studies 152, 162; described 16; visual glossary 208
Vvector 8view transform: color calibration 49; Render View 149viewing angle: defined 63; shader function 64visible light 6visual clarity 10visual hierarchy 12volume light 61, 213volume primitive 179, 181Volume Fog (material) 179-180, 182volumetric lighting 61V-Ray (renderer): described 109; case studies 148-155, 177-183
WWard (shader) 64wavelength 6-7
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