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Using High poly textures on low poly meshes [Answered]

ZBrush Usage Questions
#1

I have read that for games assets, the zbrush high poly sculpt can still be used by projecting or baking it into the low poly mesh.

How does this process work?

If I have a high poly scuplt, e.g. 8 million, how do I go about getting this onto the low poly mesh?

Also, if I wanted to retopologize, which mesh do I do that on?

Do I retopologize the high poly mesh and then create the maps? How do I then use these maps with a low poly count mesh so that it will be optimized for a game engine?

Thanks

#2

These are complex questions for answering properly on a forum of this sort. You need to get some books, or research elsewhere online to really get to grips with the whole subject. One book I can recommend and which will give you a lot of useful information is ZBrush Studio Projects: Realistic Game Characters by Ryan Kingslien.

Briefly though:

  1. Game engines and animation programs need low poly models so that characters can be animated without too much processing overhead. The way that high resolution detail is got onto the characters is through:
  • texture maps for the color detail
  • displacement, normal and bump maps for the geometry detail

Each map is mapped to the low poly model using UVs. A displacement map tells the game engine or animation renderer how to add in detail so that it looks as though there is actual high resolution geometry. A normal map or bump map creates the impression of detail by changing how the low poly model reacts to light but the outline remains the same.

  1. You may need to create new topology for your model in order for the low poly model to react well during animation. Ideally you create this new topology on the low res version of your sculpt but this isn’t essential. You then subdivide the new mesh until it has a high enough resolution to hold the detail from your original sculpt. You can then project the detail from one mesh to the other. Once you’ve done this, and your model has UVs, you can generate the maps for use with the new topology.

HTH,