ZBrush Character Creation - Advanced Digital Sculpting 2nd Edition

326 chapter 9 ■ Normal Maps, Displacement Maps, Maya, and Decimation Master

2. Click the arrow next to Bump Value to access the file node, where
   you will load your bump map. Remember just like the displace-
   ment map, this is based on 50 percent gray, so be sure to set your
   Alpha Gain value to 1 and Alpha Offset to –.5 under Color Balance
   in the file node.


3. Render your model to view the bump map effect on the surface.
   Figure 9.45 shows a character whose details exist only as a bump
   map. These can be indistinguishable from displaced fine details and in
   many cases superior since they require less render time to produce for
   the same visual effect. Figure 9.46 provides another example: the sphere
   on the left is fully displaced. The sphere on the right has a displacement
   map driving the form, while another displacement map loaded into the
   bump channel handles high-frequency details.

Figure 9.45 This character’s fine
details are carried entirely by bump
mapping.

Figure 9.46 By using a displacement map in the bump

channel, you can sharpen the fine details with minimal

impact on render times.

Common Problems When Moving into Maya

When you’re preparing a model for sculpting and displacement extraction in ZBrush, the

mesh needs to be clean. By clean, I mean it should consist of all quads (or at least nearly all

quads). Avoid triangles, poles (points where five edges or more meet), and n-gons (faces with

more than four vertices). If you find you must have a triangle, hide it in an inconspicuous

area. Triangles and n-gons may cause artifacts at render time. You also want to ensure your

vertices are all welded and that there are no nonmanifold or lamina faces. You can resolve

all of these mesh issues by using the cleanup tool. Follow these steps before you start sculpt-

ing on the model as they will potentially alter the vertex order of the mesh.

1. Select Polygons → Cleanup → OP to open the Cleanup Options dialog box (Figure 9.47).


2. If you choose Select Matching Polygons in the Cleanup Effect section and check only
   the 4-Sided Faces option, click the Cleanup button and Maya will select all the quads
   in your mesh. You can then use Edit → Invert Selection to select the nonquad faces.
   Often, I will assign another color to these faces to keep them visible and continue
   working the topology until I have an all-quad mesh.


3. Still in the Cleanup Options dialog box, choose the Cleanup Matching Polygons and
   select Lamina Faces and Nonmanifold Geometry in the Remove Geometry section.