Graphics Programs Reference
In-Depth Information
Final Gather rendering. The value of Incandescence (as well as the color) of an object is
used to calculate the overall brightness in a Final Gather scene. (See Figure 7.10.)
Figure 7.10
Incandescence
values
Incandescence = 0
Incandescence = 0.5
Incandescence = 1
Bump Mapping
This attribute creates a textured feel for the surface by adding highlights
and shadows to the render. It doesn't alter the surface of the geometry, although it makes
the surface appear to have ridges, marks, scratches, and so forth. The bump map has to
be a texture node such as a ramp, a fractal noise, or an image file. The more intense the
variation in tones of that map, the greater the bump. Bump maps are frequently used to
make surfaces look more real, because nothing in reality has a perfectly smooth surface.
Using bumps very close up may create problems; bumps are generally good for adding
inexpensive detail to a model that isn't in extreme close-up. (See Figure 7.11.)
Figure 7.11
The effects of a
bump map
No Bump Map
Fractal Texture Bump Map
Grid Texture Bump Map
Close-up geometry, where you have to change the topology of the model physically using
texture maps, requires displacement maps. We'll cover displacement maps in Chapter 11.
Diffuse
This value governs how much light is reflected from the surface in all directions.
When light strikes a surface, light disperses across the surface and helps to illuminate it.
The higher this value, the brighter its object is when lit, because more of the striking light
is reflected from the surface. The lower the Diffuse value, the more light is “absorbed” into
the surface, yielding a darker result, especially in areas that aren't well lit. Metals have very
low Diffuse values because they rely on reflections and direct light. (See Figure 7.12.)
