ZBrush Character Creation - Advanced Digital Sculpting 2nd Edition

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

In this example, we created a separate map per body part to increase quality in the final

product by allowing more texture space per body part and the use of multiple high-resolution

maps. To assign the maps, we need to create a displacement shader for each map we’ll apply

to the model.

The model in this example has eight UV regions, so eight maps are generated. The

resulting 32-bit TIFF files will be ready to apply to the mesh in Maya and should render

exactly as seen in ZBrush. To make sure each map is applied to the correct region of the

creature, open the UV Texture Editor and follow these steps.

1. Marquee-select one quadrant of UVs and choose
   Select → Convert To Faces (or press Ctrl+F9 on
   your keyboard). You can also select a few U Vs
   from one shell and then choose Select → Select
   Shell to enlarge the selection to the whole UV
   shell. Now in the Hypershade, apply the shader
   with the corresponding map to the set of faces.
   You can quickly assign shaders to selected faces
   by right-clicking your shader in the Hypershade
   and selecting Assign To Selection.


2. Once the faces that correspond to the UVs
   in each region have their own displacement
   shader applied, you are ready to render.
   Because the Alpha Gain and Alpha Offset
   settings are the same for all maps, there will
   be no discernable seams between your maps
   (Figure 9.42). Be sure that the Alpha Gain and
   Alpha Offset values are correct for each file
   node on each shader.

Setting Up 16-Bit Displacement Renders in Maya

While GoZ will set up your 16-bit renders for you, I find it valuable to understand exactly

what is being done “under the hood.” in this section I will show you exactly what process

to follow to manually set up a 16-bit displacement shader. Included on the DVD is a video

demonstrating how to render 16-bit displacement maps in Maya. The process for setting up

the shader is identical to that used for 32-bit maps. The difference comes in determining the

Alpha Gain and Alpha Offset values for the displacement map file node.

Because a 16-bit map does not have real-world scale baked in, you must adjust the

Alpha Gain and Alpha Offset values until the render appears correct. By using an expression

for Alpha Offset, you can just adjust the Gain value and Offset will update. Set Alpha Offset

to = - filenodename.alphaGain /2;. In this expression, replace filenodename with the name

of the current file node. You can find this at the top of the Attribute Editor window when you

select the file node (Figure 9.43). If the file node is called file2, use the expression = - file2

.alphaGain /2.

Test-render your displacement. If your Approximation settings are correct, you will

just need to raise the Alpha Gain value until the height of the displacement looks correct.

Figure 9.44 shows the Pixologic displacement test head. This figure illustrates a ZBrush render

of the test head on the left and a Maya render of the same head on the right. By adjusting Alpha

Figure 9.42 The final render with multiple
displacement maps