PolyPainting and Texture Maps

From ZBrush Info

PolyPainting works directly on the surface of your model.

The ZBrush approach for working with a texture map is as follows:

1. Bake texture map into PolyPainting
2. Paint using ZBrush's 3D sculpting and painting tools
3. Bake PolyPainting back to a texture map.

Note: If you want to paint on a texture map in ZBrush you must use Projection Master.

Baking a Texture Map to PolyPainting

1. Load the Model
2. Load the Texture
3. Divide the model so that its polygon count is close to your texture's pixel count. If you don't want to learn the math behind this just divide it as far as you can. If you want to learn the math, here is some info: a 2k texture map has 4 million pixels in it. Your UVs only use 70% or less of that space so the pixel count is close to 3 million.
4. Press Tool: Texture: Txr>Clr

You're done.

Baking PolyPainting into a Texture Map

1. Create a texture at the size you want for your final map. If its 2048 by 2048, follow the steps below:
   1. Set Texture: Width to 2048
   2. Set Texture: Height to 2048
   3. Press Texture New Texture
2. At this point the texture map will override your polypainting. Don't worry. Its still there.  :)
3. Do you have UVs? If yes, skip this step. If not, you have two options.
   1. Create UVs outside of ZBrush
      1. Set Tool: Geometry: SDiv to 1
      2. Export mesh by pressing Tool: Export.
      3. Layout UVs in your other application.
      4. Back in ZBrush, store a Morph Target by pressing Tool: Morph Target: Store MT.
      5. Set your model's SDiv level to 1.
      6. Import your model by pressing Tool: Import.
      7. If you have sculpted more since you laid out your UVs your mesh, at SDiv level 1, will be different. You will only want to import your UVs and not your mesh. To do this, simply restore the Morph Target, Tool: Morph Target: Switch.
   2. Create UVs inside of ZBrush
      1. Press Tool: Texture: GUV or Tool: Texture: AUV
4. Press Tool: Texture: Clr>Txr

Done!