Tutorial: ZBrush – Exporting Textures for game engines.
When using ZBrush to sculpt, you are creating high poly models that aren’t usually fit for use in game engines. You will then create a low poly version which utilizes textures such as normal maps to simulate tiny details.
There are several textures we need to export, including Diffuse, Normal Map, Displacement and Ambient Occlusion, but first we have to set up the correct mesh to add the textures to.
(Note that to use the internal renderer just to produce illustrations, the following steps rent necessary!)
Getting Textures from the High Poly to the Low poly mesh.
1: Create the finished High poly sculpt of your model and add polypaint.
2: Save your mesh as a tool for safety, then Duplicate it in the subtool menu.
3: Retopologise the cloned mesh until it is fit for use in your desired output.
4: Subdivide the retopologised mesh until it is high poly itself.
5: In the subtool Palette, with the new mesh still active, click on the original high poly mesh and click ‘Project all’. This will transfer all the little bumps and details from the original mesh to the Retopologised one.
6: Set the retopologised mesh down to it’s lowest subdivision level (i.e the level it will be used at in game) and follow this tutorial to generate the UVS. In the UV Map section of the Tools Palette, you should also set the size of your intended texture files, from one of the preset buttons.
7: Export your low poly mesh as a .obj file, ready to be rigged animated etc in an external software package.
8: Follow the steps below to export the individual textures that your model will use.
Creating the Diffuse Map is relatively simple:
1: After finishing the polypainting section of your model, open the Texture Map section of the Tool Palette. Click ‘New from Polypaint’ to Create a texture – a thumbnail of this will appear in the little blank box, shaped to match your UVs.
2: To save it, click ‘Clone Txtr‘ in the Texture Map palette, to see your texture appear in the Texture box of the Brush Palette. From here, click on it and select the ‘Export’ button, where you can save it out as a psd.
To create a normal map, you must project the fine sculpted detail form the original model onto Your low poly mesh.
1:Ensure Tangent is selected. then click Create NormalMap, and after a few seconds it will be added to the thumbnail.
2: Click Clone NM to again send a copy over to the texture box of the brush palette. Just as before, click on the Texture box and choose export to save out your Normal map.
1: Displacement maps work by projecting detail from your highest subDiv level to your lowest, so set your model to the lowest SubDivision setting then click on the Displacement Map section of the Tools Palette.
2: Make Sure the SmoothUV and Adaptive buttons are checked, then click the CreateDispMap button. It will take a few seconds to process, then again a thumbnail will appear.
3:Click CloneDisp to make a copy of the texture appear in the Alpha box of the Brush Palette. Again, click on this box an choose the export option at the bottom to save out the texture.
Ambient Occlusion Map
1: Generating Ambient occlusion can be very processor intensive so you may have to lower your subdivision level a little to make it work.
2: Go to the Masking section of the Tool Palette. Set Occlusion intensity up a little and select Mask Ambient Occlusion It will take a little while to process, then you will see the mask show on your model.
3: Click the Create Alpha button just underneath to have a new alpha map added to the Alpha window in the Brush Palette. Click on the Alpha box and choose Export at the bottom of the window that appears to save your texture.