Datasheet

30 Chapter 1: Texturing and Lighting a Product, Part 1
Another material attribute that benefi ts from custom bitmaps is the Specular Roll Off.
By mapping the Specular Roll Off, you can create the illusion that the surface is scratched,
smudged, or slightly imperfect. In this situation, it is not necessary to make a specifi c map
for a specifi c piece of geometry. Instead, you can create a “generic” bitmap that can be
mapped to multiple materials and hence multiple surfaces. For example, you can map a low-
contrast, grayscale, noisy bitmap to the Specular Roll Off attributes of the materials assigned
to the Junction_L, Junction_R, Cup_L, Cup_R, Grommet_L, and Grommet_R surfaces
(see Figure 1.36). If the pattern found within the bitmap appears too similar between sur-
faces, you can offset each instance by adjusting the Offset UV or Rotate UV attributes of
the connected 2d Placement nodes. If a surface is relatively small, such as Grommet_L or
Grommet_R, you can use a portion of the texture by reducing the Repeat UV values below
1, 1. Note that the Eccentricity and Specular Color attributes will require adjustment after
Specular Roll Off is switched from a solid color to a mapped fi le. In addition to adjusting
the Eccentricity and Specular Color to affect the size and intensity of a highlight, you can
lighten or darken the generic specularity texture within Maya. To darken the texture, lower
the texture node’s Color Gain attribute value. To lighten the texture, raise the texture node’s
Color Offset value. Color Gain and Color Offset are located in the texture node’s Color
Balance section. If you raise the Color Offset while lowering the Color Gain, you reduce the
contrast found within the texture.
Figure 1.35
(Left) A custom
bump texture with
vertical lines to repli-
cate bunched leather
and short horizontal
dashes to re-create
stitching. The texture
is included as Ear_
Pad_Bump.tgain
the ProjectFiles/
Project1/Textures
folder on the DVD.
(Right) Detail of ren-
der after the addition
of the bump texture.
A sample file is saved
as headphones
-step11.ma.
Figure 1.36
(Left) Generic
Specular Roll Off
texture. The tex-
ture is included as
Generic_Spec.tga in
the ProjectFiles/
Project1/Textures
folder on the DVD.
(Right) The result of
the texture mapped
to the ear cups and
grommets. A sample
file is saved as head
phones-step12.ma.
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