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I have a high poly sculpted mesh that I want to use to bake normal and displacement (or height) maps. I had no problem baking the normal map from the high poly to the low poly, however there is no option to bake the displacement (or height) map.

I did a little research and found that you can bake a displacement map from the high res to the low res if your object is multires, but not if they are separate objects.

Is there a work around for this? For exemple, is there a way to select a different mesh to be the higher res of the multires modifier?

By the way, I already tried using a shrink wrap modifier to make a multires from the low poly, but the result is not very good, was hoping for a better solution.

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It's a two step process.

First, give your high poly a material emitting geometry/position-- XYZ world position. Bake emission high to low, as non-color data. Save this image to a floating point, .EXR file to preserve values out of the 0,1 range.

Then, give your low poly a new material that outputs baked high position - low poly position (again, geometry/position.) Emit that and bake it. Not high to low, just a regular bake of the data. Again, non-color, and save to .EXR. You now have an XYZ displacement map.

If you don't want an XYZ displacement map, but just a grayscale displace-along-normals map, then instead of baking highPos - lowPos, bake length(highPos - lowPos), using a vector math node for the length. The nature of selected-to-active baking means that this distance is along the normal anyways. Remap that length as desired to fit inside the 0,1 range if you want.

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  • $\begingroup$ Could you post some pictures to better understand how to get the displacement map? They seem very interesting solutions, thanks. $\endgroup$
    – Riccardo
    May 28, 2022 at 14:36
  • $\begingroup$ @Riccardo If you're talking the GN edit, I don't know what I was smoking, that won't work, and I've removed that edit. $\endgroup$
    – Nathan
    May 28, 2022 at 16:05
  • $\begingroup$ Though I do not test still but if it actually work for complex structure figure well, it is really welcom (and I suppose, those manual steps can be done by bpy ,, thanks good tips! $\endgroup$
    – tokikake
    Jul 18, 2022 at 8:12
  • $\begingroup$ @Nathan ... may I also ask for more details "How to ...?" (node tree) ... I can't make it work. Thank you $\endgroup$
    – vklidu
    Nov 4, 2022 at 16:39
  • $\begingroup$ @vklidu I don't think that pictures are going to help you any more than the text. I can offer that there are a few places where people are likely to make mistakes: baking and displacing from different positions (like, baking a low poly and then doing C-C subdivision + displacement, the C-C changes pos); baking and displacing from different normals (simple subdivision changes normals with smooth shading); failing to bake and read as non-color floating point; and general baking issues like ray intersections. If you get my attention on a question with your specific problem, I'll look at it. $\endgroup$
    – Nathan
    Nov 4, 2022 at 19:43

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