Business and Computing Deanery

Multimedia

Week 21 Materials

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Last week Realtime and photorealistic Rendering Lighting concepts Types of lighting Shadows

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This week - materials Why materials? Working with materials in 3ds max Shaders and rendering Surface properties Applying maps

Bitmaps Procedural

Libraries Exporting materials

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Materials - a context… To model furniture how would you apply

material to an object to model: A shinny metal chair? Wood surface on a chest of drawers? Marble vase? A glass table top? A tumbler with blackcurrant squash? To display a wooden bowl, full of oranges? A video recorder? A stone fireplace? A metal light fitting, with the light turned on

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Concepts Consider modelling a brick wall Can you think of three ways to do it? Which would look best?

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Using materials in 3ds max Use the library that comes with the

software Make you own Apply a map

Procedural Bitmap

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Materials Materials are like paint With materials, you make apples red

and oranges orange You put the shine in chrome and the

polish on glass Materials are what make your

scenes look real

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Materials and light Light is reflected from the surfaces

of your model Consider how the light and materials

will interact Will it reflect its surroundings? Will it be bumpy or smooth? Old, clean or dirty?

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Material editor Materials

Defined Created Applied

Sample shots Parameters

Shaders Maps

3ds max v7

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Material parameters Shaders Specular Diffuse Ambient colour Specularity Glossiness Opactiy or transparency

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Rendering The computer “paints” the result of

calculation onto the screen as an image Takes into account the geometry of the

model, but also Colours Textures Light position, intensity, colour

The viewport is a preview, you need to render the scene to see the materials properly

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Shaders and rendering For standard materials, a shader is

an algorithm that tells your software how to calculate surface rendering

Each shader has a unique set of characteristics in order to serve a particular purpose

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3ds types of shaders Seven shaders used with a standard material

Anisotropic: For surfaces with elliptical, "anisotropic" highlights. These highlights are good for modeling hair, glass, or brushed metal.

Blinn: For rounder, softer highlights than Phong shading Metal: For metallic surfaces Multi-Layer: For surfaces with more complex highlights

than Anisotropic Oren-Nayar-Blinn: For matte surfaces such as fabric or

terra-cotta Phong: For surfaces with strong, circular highlights Strauss: For metallic and nonmetallic surfaces. The

Strauss shader has a simpler interface than other shaders.

Translucent: Similar to Blinn shading, the Translucent shader also lets you specify translucency, where light is scattered as it passes through the material.

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Phong Smoothes the edges between

faces and renders highlights realistically for shiny, regular surfaces

Interpolates intensities across a face based on the averaged face normals of adjacent faces.

Calculates the normal for every pixel of the face. 3ds max v7

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Blinn shading Blinn shading is a subtle variation on

Phong shading The most noticeable difference is

that highlights appear rounder

3ds max v7

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Anisotropic highlights The Anisotropic

shader creates surfaces with elliptical highlights

Good for modelling hair, glass, or brushed metal

3ds max v7

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Ray tracing Each pixel is

calculated In 3ds max it uses

mental ray renderer Generate reflections

and refractions Ray tracing traces the

path of rays sampled from the light source

Reflections and refractions generated this way are physically accurate 3ds max v7

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Surface attributes Basic material settings

Colour Specular Diffuse Ambient

Shininess Specularity Glossiness

Transparency

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Standard colour components 1. Specular

The colour of shiny highlights

2. Diffuse The colour of the

object in direct, "good" lighting

3. Ambient colour The colour of the

object in shadow

Some shaders generate the specular colour, rather than letting you choose it.

3ds max v7

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Colour Hue

Frequency of the light coming form the object

Saturation How concentrated

the colour is Value

Lightness or darkness of a colour

Additive colour model RGB

3ds max v7

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Shininess Overall reflective

nature of the object

Specularity Intensity of the

highlight Glossiness

The size of the specular highlight

Top sphere: Glossiness=100; Specular Level=100

Left sphere: Glossiness=50; Specular Level=50

Right sphere: Glossiness=0; Specular Level=0 3ds max v7

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Activity Download and open up the

materials fiel from the website

Create 6 different materials and apply them to your spheres Polished steel, brushed aluminium, red

dull plastic , red shiny plastic………….

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Transparency Transparency and

opacity are opposites

3ds max v7

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Translucency and refraction A translucent

material transmits light, but unlike a transparent material, it also scatters the light so those objects behind the material cannot be seen clearly

Simulate frosted and etched glass 3ds max v7

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Glow Appears to be lit from inside

3ds max v7

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Activity Reopen your saved file

Make a partially transparent glowing material Use the translucent shader Select self-illumination

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Materials and maps Materials describe how an object

reflects or transmits light Within a material, maps can

simulate textures, applied designs, reflections, refractions, and other effects

3ds max v7

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2D maps 2D Maps are two-dimensional

images mapped onto the surface of geometric

objects or used as environment maps to create

a background for the scene Bitmaps can be used as 2D maps Other kinds of 2D maps are

generated procedurally

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Diffuse map An image is used as

the diffuse colour Applied to the

surface of the object

Overrides the base colour Wood grain Texture of fruit Marble 3ds max v7

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Procedural maps Derived from

mathematical equations Simple or complex Do not degrade

when you zoom into them

They are 3D Marble material goes

through an object as if it were solid 3ds max v7

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Mapping textures Mapping is a method of projecting

pictorial information onto surfaces It is a lot like wrapping a present

with wrapping paper

3ds max v7

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Why use bitmaps? Stick a logo on something Making street scenes or urban

landscapes Use with billboard Used with avatars

The map is generated by a graphic artist

Use with care in real-time modelling Why?

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Tiling Repetition of an

image over a large area

Use less memory Can look too

uniform Can get join

patterns3ds max v7

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Face mapping Ignores any mapping coordinates Conforms the image to the faces

Select the desired face Apply the image

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Bump map Bump mapping

makes an object appear to have a bumpy or irregular surface

Manipulates the object’s normals Does not affect the

object’s mesh 3ds max v7

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Mapping coordinates Use x, y z coodinates

3ds max v7

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UVW co-ordinates Most material maps are a 2D plane

assigned to a 3D surface. The coordinate system used to

describe the placement and transformation of maps

Mapping coordinates use the letters U, V, and W The three letters preceding X, Y, and Z

in the alphabet.

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Activity Add a procedural map to your scene

Wood Marble

Change the colours and grain

Add a bitmap to a material in your scene

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Material libraries Materials used in a model are saved

in the max file

The software comes with libraries of materials

Create your own materials Which can then be saved to a library

for use on another project Make a library from a particular scene

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Special libraries Ray trace

Attempts to physically model a surface instead of simulating it

Form of rendering that calculates rays of light

Supports advanced transparency parameters such as fog

Architectural Actual physical properties Use with photometric lights to model

real-life objects

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Activity Use the material library to add the

following: Clear glass Earth Clouds Mirror

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Animated textures Use an animation or video

A model of a TV May loop Think about transitions

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Environments You can use an

image as a background Rendering>Environm

ents

3ds max v7

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Bitmaps for exported models Exported files do not always take

colours or textures with them If you use Bitmaps you need to

collect themFile menu > Archive > Resource

Collector

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Activity Export your model as VRML Collect all the maps into a ‘maps’

folder

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Self assessment You have been asked to model a

prototype toy car Describe three ways of applying

materials List and describe the 7 parameters of

materials

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For Next Week Submit your Portfolio 2.3 Work on your model

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References Giambruno M, (2002) 3D Graphics & Animation,

2nd Edition, New Riders, ISBN: 0-7357-1243-3 Kerlow I. V., (2003) The Art of 3-D Computer

Animation and Effects , 3rd Edition, John Wiley & Sons Inc; ISBN: 0471430366

Murdock K.L., (2005) 3DS Max 7 Bible, John Wiley & Sons Inc, ISBN: 0764579711

Screen shots taken from 3ds max 7 User Reference