du/dv map

Note:$dudvmap is now defunct and is replaced by the Refract shader. Though, the Water shader still uses a du/dv map for $bumpmap.

du/dv maps are used for DirectX 8 refractions. If you're a Photoshop user, it's easy to create du/dv maps using nVidia's texture tools.

Creating a du/dv map from a normal map

A du/dv map can be easily created from a normal map in just two steps. You can also do this if you don't want to bother with the nVidia tools.

Note:Work from the source texture (such as a .tga) if possible.

Photoshop

1. Open the normal map and invert the colours (Image > Adjustments > Invert or Ctrl+I).
2. Go to Image > Adjustments > Brightness/Contrast.
   1. Check "Use Legacy"
   2. Set Brightness to -17
   3. Set Contrast to 100

Paint Shop Pro

1. Open the normal map and invert the colours (Colors > Negative Image).
2. Adjust the contrast as high as it will go.

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You now have a finished du/dv map. When converting to a VTF, set the format to UV88.

See also

• Normal2dudv - utility to convert normal maps to dudv maps
• Height2Normal - utility to convert height maps to normal maps
• Filter Forge