Cavity and Ambient Occlusion Maps (Normal Maps, Displacement Maps, Maya, and Decimation Master) (ZBrush Character Creation) Part 2

Multiple UV Regions and Multi Map Exporter

The Multi Map Exporter plug-in supports multiple UV regions. If the plug-in detects that you have UVs outside 0 to 1, it will generate full-resolution maps for each UV region. This approach, combined with HD geometry, makes it possible to generate multiple extremely high-resolution maps of high quality from the sculpture or polypaint data in ZBrush.

Using Multi Map Exporter

The strength of this plug-in is the ability to export multiple map types with individual settings from a single or multiple UV regions with a single button click. It automates many repetitive tasks into a single, easy-to-use interface. To generate a series of maps from Multi Map Exporter, follow these steps:

1. Load the werefolf.ztl file from the accompanying DVD.

The Ambient Occlusion Map menu

Figure 9.76 The Ambient Occlusion Map menu

The Cavity Map menu options

Figure 9.77 The Cavity Map menu options

The Export Mesh menu

Figure 9.78 The Export Mesh menu

2.    Open the ZPlugin + Multi Map Exporter menu.

3.    Enable Displacement, Normal, Ambient Occlusion, Cavity, and Export Mesh.

4.    Set Map Size to 4096 to generate 4K maps (Figure 9.79).

5.    Open the Export Options submenu and expand the Displacement Map options. Set SubDiv Level to 1, turn 3 Channels on, and click the Get Scale button to establish object scale. This will help generate a more accurate 16-bit map since object scale isn’t baked into the map itself.

The Get Scale button estimates a suitable value for the Scale slider to produce a 16-bit displacement map that is similar to an optimized version for the selected subtool. Different subtools can give widely varying results, so it is important to assess which Scale value will produce the best results for your needs. In general, use the lower range of values to avoid clipping.

Use the Intensity or Alpha Depth option when applying 16-bit maps. This value is set when you click the Get Scale button. User input values are added to the filenames when you turn on the 16 Bit Scale option, but the value has no effect on displacement map creation.

6.    Open the Normal Map, Ambient Occlusion Map, and Cavity Map menus. Set your settings to match Figure 9.80.

7.    Under the Mesh Export menu, set SubDiv Level to 1. Now click the Create All Maps button at the top of the menu to generate maps from the settings you just entered. Multi Map Exporter will ask for a location to store the files. Browse to a suitable folder and click Save. The maps will begin to generate.

8.    The maps will complete and the mesh will export as an OBJ file. Figure 9.81 shows the resulting maps in my folder. The scale is indicated in the displacement map filename; this value helps you determine the Alpha Gain value when rendering.

Enable the following options on the Multi Map Exporter menu.

Figure 9.79 Enable the following options on the Multi Map Exporter menu.

Match your settings to the ones in this image.

Figure 9.80 Match your settings to the ones in this image.

The resulting maps and mesh file

Figure 9.81 The resulting maps and mesh file

That completes our discussion of Multi Map Exporter. The plug-in is as simple to use as it is powerful. Any map you could want to create with ZBrush can be automated using the process you just learned. We will now look at another way of getting your work out of ZBrush: decimating meshes.

Exporting with Decimation Master

Decimation Master is a ZBrush plug-in that allows you to reduce the overall polygon count (and thus the file size!) of a fully sculpted high-res mesh without sacrificing details. It accomplishes this through a process known as decimation.

Most of this topic has been concerned with exporting maps from ZBrush that help recreate the look of the detailed model in an outside program. Decimation Master is unique in that it allows you to selectively reduce or decimate the ZTool so you retain the fine details but with fewer polygon faces. This is accomplished by triangulating the mesh to varying degrees along the surface of the model. You can use Decimation Master to export your ZTools with color information as OBJ files to be rendered in 3D programs. You can also use this plug-in to prepare models for 3D print. Most 3D printers have a file size limit on the data you try to print. Using Decimation Master allows you to create 3D models that will not only retain their surface details but will also be suitable for printing on a rapid prototype machine.

In this section you’ll learn how to take a highly detailed creature bust and decimate it to under a million polygons while retaining the color information as well as surface details.

1.    Load the alien head ZTool from the DVD. Step down to the lowest subdivision level and generate AUV or any other suitable UV mapping for the head.

2.    Step up to the highest subdivision level and generate a texture map from the polypaint data by clicking Tool + Texture Map + New From Polypaint.

3.    Open the ZPlugin + Decimation Master menu. Enable Keep UVs so the map you created will still work on the decimated model. If you were merely exporting for 3D print, you could disable Keep UVs.

4.    Since you are working with only one subtool, click Preprocess Current. If you want to process multiple subtools at once, you can click Preprocess All at this stage. ZBrush will now process the highest subdivision level mesh, writing a cache file to help it decimate the mesh to a specified polygon count.

5.    Once the preprocess is finished, set the percentage of decimation or a target poly count. The k Polys sliders is in 100,000 polygons, so 200 is actually 200,000 triangles. Set this slider to 900 for a resulting 900,000 triangle mesh. Now click Decimate Current to complete the process. Figure 9.82 shows the original ZTool beside the decimated version. Figure 9.83 shows the decimated model with the texture map applied, displayed in the Maya viewport ready for rendering.

You can get exceptional results rendering decimated meshes in Maya and bypassing the need for normal, bump, and displacement maps altogether. Figure 9.84 shows a frame from a turntable rotation I rendered using the decimated head from this section. See the DVD for this Maya scene file to render on your own—it is called highResAlienRender.mb.

The original ZTool and the decimated version on the right

Figure 9.82 The original ZTool and the decimated version on the right

The decimated model and texture map displayed in the Maya viewport

Figure 9.83 The decimated model and texture map displayed in the Maya viewport

A Maya render of a decimated mesh. This scene file is included on the DVD.

Figure 9.84 A Maya render of a decimated mesh. This scene file is included on the DVD.

3D Printing

3D printing, or milling, is the process by which 3D models are generated in the real world either by extruding layers of plastic on a 3D printer or with the carving process of a 3D mill. 3D printing is best for small to medium objects with high details whereas milling works best for larger objects. Gentle Giant Studios and Weta Workshop produced a life-sized King Kong for the movie premiere in New York City in 2005 by milling from digital sculpture data.

Figure 9.85 shows several examples of some figures I printed while working as digital art director at Gentle Giant Studios.

 These figures were created using 3D printing ZBrush data.

Figure 9.85 These figures were created using 3D printing ZBrush data.

Featured Artist: The Art of Damien Canderle

Damien is a freelance ZBrush artist whose striking renders have inspired many of us in the ZBrush community. I especially love the attention to color, light, and atmosphere in the third image.




Next post:

Previous post: