ZBrush Character Creation - Advanced Digital Sculpting 2nd Edition

■ Cavity and Ambient Occlusion Maps 333

Figure 9.64 The file node window in
the Attribute Editor

Figure 9.65 This character head is rendered with a normal map. The first image is

the normal map with wireframe in the Maya viewport. The second image shows

the normal map rendered in the Maya viewport. The third image is the normal

mapped mesh rendered in mental ray with Final Gather and Image Based Lighting.

Congratulations! You have now created and applied a
normal map in Maya.

Cavity and Ambient Occlusion Maps

Cavity and Ambient Occlusion maps are specialty
textures that can be generated in ZBrush using the
masking tools. Cavity maps are essentially the blue
channel of a normal map and represent dark shading
in the crevices of the model. They can be useful as a
multiply layer over a diffuse color map to accentu-
ate details or as a diffuse map in Maya to help punch
up the high-frequency details in a render. Figure 9.67
shows a cavity map. It is essentially a black-and-white
map in which black represents the recesses and white is
the high points.
Cavity mapping is intended to help
mimic Ambient Occlusion, but it is not by nature
an Ambient Occlusion effect. It also has several other
uses. Ambient Occlusion works by casting rays out
from the surface of a 3D model. If a ray hits another
surface before dying out, then a grayscale value
is recorded that represents how far that ray trav-
eled before being occluded. This is how Ambient
Occlusion maps generate darker shadows in tight
recesses like inside ears or under the brow ridge.

Figure 9.66 Selecting mental ray as the renderer

Figure 9.67 A cavity map