Business and Computing Deanery 3D Modelling Tools Week 16 – Lighting.

Business and Computing Deanery

3D Modelling Tools

Week 16 – Lighting

3D Modelling Tools 2

This weekLecture Lighting

Rendering Computer graphics Standard lights Shadows

3DS Max 7 Bible Chapter 27


Rendering Rendering "fills in" geometry with

color, shadow, lighting effects, etc. Converts three dimensional scenes

to two dimensional screens by following rays of light from the eye of the observer to a light source


Photorealistic rendering “In computer graphics, photorealistic

rendering attempts to make artificial images of simulated 3d environments that look just like the real world.”

Reynolds (2003)

Where is it used? What are the implications?

Hardware Time Interactivity


Realtime rendering Relies on graphics cards with 3D

hardware accelerators Where is it used? What are the implications?

Hardware? Time Interactivity


Rendering techniques 1 Ray casting

Renders the scene as observed from a specific point-of-view based only on geometry using very basic optical laws of reflection intensity

Does not render accurately reflections, refractions, or the natural fall off of shadows


Rendering techniques 2 Ray tracing

Similar to ray casting, but employs more advanced optical simulation

Can use multiple rays Traced through a

number of sequential 'bounces‘

Realistic reflections and shadows

Too slow to consider for realtime

3ds max v7


Rendering techniques 3 Radiosity

Uses finite element mathematics to simulate diffuse spreading of light from surfaces

Rendering technology that realistically simulates the way in which light interacts in an environment 3ds max v7


ComparisonLighting Algorithm

Advantages Disadvantages

Ray-Tracing

Accurately renders direct illumination, shadows, specular reflections, and transparency effects. Memory Efficient

Computationally expensive. The time required to produce an image is greatly affected by the number of light sources. Process must be repeated for each view (view dependent). Doesn’t account for diffuse interreflections.

Radiosity

Calculates diffuse interreflections between surfaces. Provides view independent solutions for fast display of arbitrary views. Offers immediate visual results.

3D mesh requires more memory than the original surfaces. Surface sampling algorithm is more susceptible to imaging artifacts than ray-tracing. Doesn’t account for specular reflections or transparency effects.

3ds max v7


Render farms Rendering networks are sometimes called

“render farms.” In the software, one computer is set up as

the network Manager. The Manager "farms out" or distributes the

work to rendering Servers. Pixar have created Renderman

10 years ago it took 6 hours to render one frame

How many today? Use render farms


Lighting - realtime v. photorealistic Compare lighting

OpenGL - max 8 lights Photorealistic – 10 lights per character

Convergence of realtime and photorealistic Realtime is now used to plan real

movies Used extensively in games


Internalor3rd party

Traditional

The CG production pipelineStory

Art

Set design Layout Animation Shading

Modelling

Rendering

Lighting Simulation Effects

Film

Commercial

Editorial


Concepts Light has warmth (yellowish) or

coolness (bluish) Intensity Angle if incidence Radiosity

Light reflecting from an object Attenuation

Light becomes weaker with distance3ds max v7


Lighting basics Three main sources of lighting in

classic photography Key Fill Backlight

Concepts apply to 3D programs, plus Ambient light


Getting it right

3ds max v7


Key light Outdoors

The sun Indoors

Major window Main electric light Flash on a camera Spot light on a stage


Fill and key lights Fills in the dark shadows

cast by the key light Outdoors may be created

artificially Indoors from secondary

lights Distant window Light fitting

Softens shadows 3ds max v7


Backlight Situated behind the subject Separates the foreground from the

background Can make the scene more three-

dimensional


Lighting strategies

3ds max v7


Planning lighting Default lighting Use this until you are happy with the

scene, then add lights Use as few as possible Start with the key light

Maybe a spot Add fill

Use omni or several spots Finally add accent lighting

3ds max v7


Ambient light Not a light source

Light from other sources bouncing of walls, the ceiling and other objects in the scene

3ds max v7


Types of lighting Standard

Spotlights Omnidirectional light Directional light

Advanced Photometric lights


Spotlights Casts a focused beam of light like a

flashlight, a follow spot in a theatre, or a car headlight

3ds max v7


Omnidirectional light Known as omni light Like a bare light bulb Casts rays in all directions from a

single source

3ds max v7


Directional light Also known as Distant lights Cast parallel light rays Primarily used to simulate sunlight


Target lights Concept like cameras Target

Easier to aim Simply position the target object at

the centre of interest Free

3ds max v7


Lighting directionSingle light from side Single light straight on

Both sides Reduced full fill

3ds max v7


Activity Create a flat surface with a sphere

and a cone sitting on top Add one or more spotlights to

provide lighting and render the scene Experiment with moving them around

and rendering the effect Add an omni light behind the scene Alter the values to achieve a

balanced rendering


Standard light settings Intensity Angle of incidence Attenuation Reflected light and ambient light Colour


Attenuation Natural reduction

of light intensity

3ds max v7


Brightness and colour Intensity sets the brightness of the

scene Range from 0 to 255 (white) Colour – use the RGB sliders

3ds max v7


Activity With your scene experiment with

your light settings Vary the light settings for:

Intensity Angle of incidence Attenuation Reflected light and ambient light Colour


Use of shadows

Default lighting

Spot plus low level back lighting

Spot

3ds max v7


Shadows Photometric and standard lights

both have the same options for generating shadows

Two types Shadow mapped Ray-traced


Shadow mapped Grayscaled texture map based on the

lighting and mesh Soft-edged More natural May be blocky May be inaccurate May be incorrectly positioned Do not take transparency into account Do not take on the colour cast of the

object May use a lot of RAM 3ds max v7


Ray traced shadows Ray tracing

techniques Have a hard edge

Software can be used to soften

Very accurate and precise

Does not use a lot of RAM 3ds max v7


Hotspot and falloff Hotspot

Angle of the inner portion of the beam

Falloff Angle of the outer

beam Differences in

angles make the effect softer

3ds max v7


Include and exclude Some software allows you to set up

lights that affect only certain objects Use a pick list to select objects


Colour and mood Cool colours – blues and violets

Still and calm Warm colours – yellows, red and

orange Fiery and energetic Intense and active

Be careful, keep it subtle


Activity Create a flat surface with a sphere

and a cone sitting on top Add a spot light Add a fill light

Alter the hotspot/fallout Alter the type of shadow


Photometric lights Photometric lights

enable you to more accurately define lights as they would be in the real world using ray tracing

Distribution, intensity, colour temperature can be set 3ds max v7


Global Illumination with Radiosity Standard lights are simpler than

natural lighting Using photometric lights with a

radiosity solution with your lights provides a better model of the real world

Radiosity is rendering technology that realistically simulates the way in which light interacts in an environment


Preset photometric lights Generic 60W Bulb Generic 75W Bulb Generic 100W Bulb Generic Halogen Spotlight Generic Recessed 75W Lamp (web) Generic Recessed 75W Wallwash (web) Generic Recessed 250W Wallwash (web) Generic 4ft Pendant Fluorescent (web) Generic 4ft Cove Fluorescent (web) Generic Street 400W Lamp (web) Generic Stadium 100W Lamp (web)


Photometric lights Target Point

Similar to a standard omni light, emits light from a geometric point

Spotlight Focused beam

Web distribution Distribution of light Many lighting manufacturers provide

web files that model their products 3ds max v7


Sunlight and Daylight A system that follows the

geographically correct angle and movement of the sun over the earth at a given location

You can choose Location Date and time Compass orientation.

3ds max v7


Daylight Daylight combines sunlight and

skylight The sunlight component can be either IES Sun light

Illuminating Engineering Society Values set automatically based on geographic

location, time, and date Or a standard light (a target direct light).

The sky component can be either an IES Sky light Or a Skylight.


Portfolio 9 Create a model with a cone, sphere

and tube sitting on a flat surface with lighting to show: Strong directional lighting, similar to on

a stage A general well lit scene

Produce 2 A4 sheets, one for each scene containing a small rendering of the scene and an annotated plan showing and describing the lights used


Questions List and describe three different light

types used in 3D modelling giving their parameters and examples of their use

Describe, giving light types, parameters and positions how you would light a scene: A stage A well lit indoor room A darkened room light by a candle

Consider how this might be done as a storyboard Discuss the difficulties in including

shadows within games


Impendent study Directed reading 3DS Max 7 Bible

Read Chapters 27 Portfolio 9 Tutorials

Introduction to Lighting


References 3ds max v7, (2005) User Reference

and Tutorials Murdock K.L., (2005) 3DS Max 7

Bible, John Wiley & Sons Inc, ISBN: 0764579711

Reynolds C., (2003) Stylized Depiction: Non-Photorealistic, Painterly and 'Toon Rendering, http://www.red3d.com/cwr/npr/ accessed 09/01/2007

Business and Computing Deanery 3D Modelling Tools Week 16 – Lighting.

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