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11Materials
3. Quick Tutorial: Materials
A well-modeled object can make a mediocre impression if the right textures aren’t used. Textures give a model color,
highlights, structure and other important surface properties. A texture placed into the Bump channel, for example,
gives the object’s surface an uneven, bumpy look without actually altering the geometric structure. This effect can be
used to imitate skin wrinkles, scars or the surface of an orange. The displacement channel works in a similar fashion,
only that it actually does change an object’s geometric structure. In short: Textures have the same significance as
the outer shape of an object because they are necessary for achieving the desired atmosphere, coloring and surface
structure.
We will begin with a brief introduction to the individual material channels:
Color: This is where the material’s color or the base color for the texture is set.
Diffusion: This channel makes your texture irregular. Through the application of a shader or a texture
your object receives a dirty or dusty look. If desired it can also influence the Reflectance and Luminance
channels, respectively, and the specular highlight.
Luminance: The material is given an illuminative property which is also taken into account in the Global
Illumination calculation.
Transparency: This is where you determine the material’s transparency.
Reflectance: Gives the material reflective characteristics and defines the material’s highlights and highlight
colors.
Environment: A texture is used to simulate an environment reflection.
Fog: This channel lets you apply a fog property to a material.
Bump: Uses an optical trick to translate light and dark elements of a texture or a shader to simulate the
height and depth of an uneven surface. Scars, wrinkles or scratches can be simulated using this channel. If
the Parallax Offset function is also enabled for this channel, the result will be even more realistic but will not
match the quality of a displacement. However, the Parallax option offers much shorter render times.
Normal: This channel is meant for use with normal textures. Normals give a low-res polygon object a hi-res
look when RGB textures containing the required properties are applied. This lets a hi-res polygon object be
replaced by a low-res object, thus saving a lot of render time and offering the same visual result.
Alpha: A texture’s transparency is determined by a material’s light and dark areas. Black equals a transparency
of 100 % and white makes it opaque.
Glow: Gives the object a self-emitting glow.
Displacement: Deforms an object using light and dark values (calculates differences in height). Do not con-
fuse this with the Bump channel which only imitates an uneven surface.