334 chapter 9 ■ Normal Maps, Displacement Maps, Maya, and Decimation Master
The rays there intersect the next surface faster than, say, faces under the chin, which would
record a lighter grayscale value.
Cavity mapping, on the other hand, just shades in recesses. It doesn’t use advanced
raycasting or calculate distances between surfaces. It is, however, useful as a diffuse map or
a Photoshop mask or any other application where you want to isolate the high points from
the low points on a surface texture. Figure 9.68 shows a cavity map and Ambient Occlusion
map to help illustrate the differences.Figure 9.68 A cavity map and an Ambient Occlusion map. The first image is a cavity map. Notice
how the recesses are shaded whereas the Ambient Occlusion image shows a gradient shading into
the recessed areas of the head.Cavity maps are generated with ZBrush’s Masking menu. You can automate this pro-
cess a bit more by generating the maps using the Multi Map Exporter plug-in we will dis-
cuss in the upcoming section “Creating Maps Using Multi Map Exporter.” The curve used
here will also affect the maps generated with the Multi Map Exporter plug-in. Follow these
steps to create a cavity map:- Load your ZTool and step to the highest subdivision level. Tools with more fine details
tend to give better results. Make sure the mesh has UV coordinates applied. - Open Tool → Masking and click the Cavity Profile curve to open it. Change the curve
to look like the one in Figure 9.69. Set Intensity and Blur to 10. Click Mask By Cavity to
mask into the recessed areas. Figure 9.70 shows the masked head.
Figure 9.70 This character head has cavity masking applied.Figure 9.69 The
Masking menu
here shows the
curve settings
required to cre-
ate a cavity map.