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Bake from Multires: Displacement
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Description

Blender Version
Broken: c760285ae01

Short description of error
There are a few problems I kept encountering when trying out the "Bake from Multires" in both the old Blender Internal and Cycles.
These problems are still visible even now, for example when I bake a Displament map from the Multires modifier.

(Original Multires Sculpt)

(Baked Multires)

The result never really matches the original in multiple ways.
I experimented further with a couple of simple strokes on a cube with Multires Level 6.


But once I baked a 16 bit displacement map from multires onto the level 1 subdivision of the same cube
and used that texture via the displacement node in the material, it looks like this.
I used both displacement and bump for this picture.


The big negative point is that the overall displacement never matches the original mesh, regardless of how I set the midlevel and scale settings in the materials or even the displacement modifier.


When looking just at the displacement we can see that on the 12 edges of the cube mesh the displacement breaks.


And when just using the texture via the bump node for the normals, the baked high-res geometry is clearly visible as if set to "shade flat".

Here is the .blend file I used for the cube example.

There might also be some settings that I missed but at this point I really don't know anymore.

Details

Type
Bug

Event Timeline

The issue of the volumes not matching with the displacement map seems to be largely fixed T57517.
There are still some small differences but I think these are due to the lack of vector displacement.

(Left=Displacement+Bump - Right=Multires)

Sebastian Parborg (zeddb) closed this task as Resolved.Feb 1 2019, 8:32 PM

@Sergey Sharybin (sergey) I agreed with @Julien Kaspar (JulienKaspar) that it seems like the remaining differences would be due to lack of vector displacement.

But if this isn't the case, then I am indeed mistaken and this should be reopened.

AFAIR, we do have vector displacement now (and hence can test)?

P.S. Currently in the middle of something else, so can't really look into yet myself.

Discussed in IRC, this is about vector displacement for baking, not for render

Discussed in IRC, this is about vector displacement for baking, not for render

Yes, sorry. That was what I was referring to.
The big issue I had was that the volumes of the baked result and the sculpted original didn't match up at all. I thought the other issues were connected but that might not be the case so it is probably best for me to make a separate bug reports on that.

I would say the bug is fixed. There are still differences in the latest screenshots but those are probably because usual displacement can't give the most accurate results. Vector displacement baking, and using these baked maps would yield better results but this is not yet possible in Blender.