
	Rendering

Once all the mapping parameters are set for each patch, you can render out the textures. Open up the Rendering panel to see all the rendering controls (see Figure 124).

Figure 124. Rendering Controls

(1)

You can choose which directory you want the texture maps saved into by clicking on the right arrow after the Dir. field. A directory selection dialog will pop up; use that to find and select the directory.

(2)

Choose which output format you want by selecting either sgi, tiff or tiff16. If you use either of the first two choices, then the displacement maps will be 8-bit. If your rendering software supports 16-bit images, tiff16 is recommended.

(3)

You can also select either bw or rgb output for the displacement maps. The shading will still be grey scale, but some renderers and image conversion programs seem to have problems with single channel SGI and/or TIFF files. Color and Normal maps are always RGB, regardless of the setting of this option.

(4)

When rendering NURBS surfaces, you can globally increase or decrease the pixel dimensions of the rendered maps by putting a percentage scaling into the Size field. For example, of you just wanted to do a quick test, then setting the scale to 50% would reduce the map rendering time by four times.

(5)

Also when rendering NURBS, by default CySlice will write out an Alias|Wavefront Maya MEL script shader definition for each patch. These MEL scripts are based on templates that can be found in the $HEADUS_HOME/lib directory. If you would like more information on this feature, send email to architec@headus.com.au .

If you aren't using Maya, then you can safely switch off the Write Maya SGs toggle.

(6)

If you want to view the rendered maps after the calculations are complete, enable the Show After Calc toggle. Be careful though; if you have 100 patches in your NURBS surface, with both displacement and color maps being calculated, 200 images will be displayed! However, when rendering out maps for a SUBD surface, only a few large images will be displayed.

Figure 125. Displacement Calculations

(7)

The new default behavior for displacement maps is for the error to be calculated to faces with similar normals to the NURB or SUBD surface. That is, displacement errors are only calculated to facing faces. The old method was for the error to be calculated to the closest faces, and in tight areas (such as between fingers or under arm pits) the error was often messy. You can re-enable the old behavior if you want by unchecking the Error To Facing Only toggle.

After deciding on the output directory, file format, and so on, you are ready to calculate the texture maps. The time taken will depend upon the complexity of the polymesh, the pixel dimensions of the maps, and of course, the speed of your computer. In a worst case scenario it could take several hours, so be prepared to run this overnight.

So, to calculate the maps for all visible patches, click on the Calc Now button. It will change into a red Abort button; click on that if you want to abort the map calculation process at any point.

If you don't want to calculate maps for a selection of patches, there are two methods. Either hide the patches you want to exclude from the rendering process (i.e. only visible patches are rendered), or disable both Disp and Color in each patch's Texture Maps properties. This option is only available for NURBS surfaces.

Additional SUBD Controls

When maps for SUBD surfaces are being rendered, a few additional controls are available (see Figure 126).

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Figure 126. Additional SUBD Controls

(1) If Patch Color is enabled the color is replaced with different solid colors for each patch.

(2) If Show Grid is on then the network grid is drawn over the color, displacement and normal maps.

(3) If Name is on then patch names are also drawn over all rendered maps.

Figure 127. Patch Color, Grid and Names

Figure 127 shows a SUBD surface, textured with a color map created with all the above options enabled.
The Quality setting would normally be on High. If map renders are taking longer than you want to wait, you can reduce this setting to speed things up. The Quality setting controls the level of subdivision of the surface before the map extraction calculations are performed; by reducing the quality you're reducing the subdivision level, and this can impact on the accuracy of the maps, especially the displacement maps.

NURBS File Names

The name of each color texture map file is based on this pattern: patch_name.format . So, for example, if the patch is called nose1, and the output is TIFF, then the color map file will be called nose1.tif.

The name of the displacement maps follows this pattern: patchname_maxerror.format . If our nose1 patch has a Max Error of 2.5mm, then the displacement map file will be called nose1_2.5.tif.

SUBD File Names

The name of the color texture map file is based on this pattern: firstpatchname-res.format . So, for example, if the first patch is called "fish", the map UVs have been built to a size of 512 pixels, and the output is TIFF, then the color map file will be called fish-512.tif.
The name of the displacement map follows this pattern: firstpatchname-res_maxerror.format . If our 512 pixel map has a Max Error of 2.5mm, then the displacement map file will be called fish-512_2.5.tif.