Datasheet

Project: Applying Textures  25
In this case, it’s best to choose a resolution that will match the desired resolution of
the final texture. For example, 1024×1024 is appropriate for a small piece of geom-
etry when rendering at HD 720. Change the Image Format menu to a format that’s
supported by a digital paint program (such as Photoshop). For example, JPEG is a
commonly used format that produces sufficient quality for the texture-painting
process. (If you choose an image format that supports alpha, such as Targa or TIFF,
the UV information will be written to an alpha channel.) Click the OK button. The
UV texture space is written out with the name and
location defined by the File Name attribute.
2. Launch Photoshop. Open the UV snapshot file you just
wrote out. The UV texture space appears with the UV
shells laid out in white over a black background (see
Figure 1.28). By default, only the 0 to 1.0 UV space is
included. U runs left to right, and V runs down to up
with 0, 0 at the bottom-left corner. (If UV shells or
UV points fall outside the 0 to 1.0 area, they receive a
repeated part of the texture.) Note that the tubes run-
ning through the center of the Junction_R surface
overlap the surface sides. Overlapping faces share
the same part of any assigned texture. For this
reason, you usually want to avoid such overlap.
However, in this situation, the overlap is unim-
portant because the walls of the tubes are not
seen by the rendering camera.
3. In Photoshop, double-click the Background layer
in the Layers panel. The New Layer window
opens. Enter a new name, such as UV Snapshot,
into the Name field, and click OK. This converts
the locked Background layer into a layer that you
can reposition in the layer stack. Choose Layer

New

Layer. Double-click the new layer to open
the New Layer window. Enter a new name, such
as Textu re, into the Name field, and click OK.
LMB+drag the UV Snapshot layer to the top of
the layer stack. Change the UV Snapshot layer’s
blending mode menu from Normal to Screen. The
Screen blending mode allows the white lines of
the snapshot to appear over the lower texture layer.
An example PSD file with this setup is included
Figure 1.27
The UV Snapshot window
Figure 1.28
A UV snapshot of the Junction_R surface as seen in Photoshop.
The arrows point to several areas where polygon faces overlap in
the UV texture space.
903278c01.indd 25 4/13/11 10:08:56 AM