business and computing deanery multimedia week 21 materials
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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