ZBrush Character Creation - Advanced Digital Sculpting 2nd Edition

■ Generating Displacement Maps 315

The difference between DPSubPix mode and Adaptive mode is in how the displacement

map is generated. DPSubPix mode is a global subdivision value. With DPSubPix set to

2, for instance, when ZBrush generates the map it subdivides the entire mesh two more

times in memory, thus allowing you to create a crisper, higher-quality map. Adaptive, on

the other hand, is a feature-based displacement mode. This means that as the map gener-

ates, ZBrush will subdivide only those areas of high detail. For this reason, adaptive mode

is sometimes faster than DPSubPix. Both map types have their benefits.

Processing Displacement Maps for Use in mental ray

It is important to remember that with the 32-bit map export, there is no reason to open your
map in external image-editing software and resave it. In many cases this will destroy the
floating-point data and render the map useless.
Maya provides a nice utility called imf_info.exe in the Maya/bin directory. You can use
this program at the command line to read detailed information about your displacement map.
imf_disp.exe is another utility that will display maps and offer information on them.
This utility features a graphic interface.

Your displacement maps will perform far better, faster, and with more stability in mental

ray if you convert them to the mental ray native file format, MAP. The difference is espe-

cially apparent with higher-resolution maps. Maya will process the render at a noticeable

speed increase in many cases, and crashes are less common when working with larger

map resolutions. Using the MAP file format will also increase your speed at render time

because MAP files use mental ray’s memory-caching features. Taking care with how men-

tal ray handles memory will speed up renders and make for far better performance. This

process is automated in newer versions of Maya but this section will show you how to

manually convert any file to the MAP format.

mental ray comes with another command-line utility called imf_copy, which will
allow you to convert TIFF files to the MAP format. To run this utility, open a command
window in the folder where your TIFF files are located. Use the following command line to
convert to MAP format:

imf_copy​-p​originalfile.tif​newfilename.map

To open the command window on a Windows machine, choose Start → Run and type

command.

Perform this conversion on all displacement maps you plan to use. The maps will cache
in memory and render faster and with fewer crashes. Included on the DVD is a Windows
batch file to automate this conversion process. Simply drag and drop your TIFF files onto the
convertfile.bat icon, and they will convert and save in the original location.