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I've created a displacement map which is based on the height of the mesh. The problem is that by the nature of this organic texture there is some self-intersecting geometry. I don't believe this can be avoided in this case, but I need to remove the resulting dark areas from the render because they will create unrealistically deep pits in the displacement. If I can do this at the rendering stage it will save a lot of time in the image post-processing stage, and produce more consistent and accurate results.

Displacement map with dark image artifacts in the cracks

Dark spots in the cracks = bad.

I tried isolating back-facing geometry and treating it the same as front-facing. This made no difference though, so it must be something about the layering of the geometry rather than the facing angle. I didn't expect to have such trouble with a simple height map gradient, but the overlapping geometry has turned out to be a challenge.

Any help appreciated.

Mentalist
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  • I've looked into your file but I didn't figure it out, but maybe you can resolve it by making cracks without intersection. Check this: https://blender.stackexchange.com/questions/52284/voronoi-cracks-fac – cgslav Jun 18 '17 at 19:31
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    I've also looked into your file (with all the modifiers applied in the Viewport mode). It appears that the dark spots are real holes, and not an effect of the shader. You can zoom in and look around in "solid" view and see that it's actually a matter of topology. – Nicola Sap Jun 18 '17 at 19:34
  • @NicolaSap Good observation about the holes. Since this is organic-style geometry being generated procedurally, I don't have precise control over the topology. This is a bit frustrating, but I think it can't be helped. But maybe there is a way to isolate the problem areas and additively blend them back in at more accurate values, or maybe just blur them in the compositor. Of course, smudging them out in Photoshop is the last resort and will work, but I can't help thinking there must be a better way. I'm open to any ideas. – Mentalist Jun 18 '17 at 19:45
  • @NicolaSap I'm thinking now that if I can isolate both the backfacing geometry and the holes (using the sky alpha) this might be all the information needed to create the necessary masks that can be used in the compositor to blur and/or lighten these problem areas. This is still all hypothetical at this point. More testing is needed. – Mentalist Jun 18 '17 at 20:01
  • Yep, it seem Remesh is causing actual wholes in the mesh continuity. Would cheating and adding a fake backdrop plane object behind the current one using the same shader suffice to fix it? – Duarte Farrajota Ramos Jun 18 '17 at 20:14
  • @DuarteFarrajotaRamos If I were using normalized Z-Depth to generate the height data, sure, that is one approach to cap the limit of the gradient. But instead I chose to base the gradient only on the geometry. (you can see by my material node setup that an empty is being used to generate the start and end points of the gradient.) So adding a fake backdrop plane in this case adds no benefit - the height data is already as accurate as it can be. The only thing that needs fixing is artifacts caused by the messy geometry. – Mentalist Jun 18 '17 at 21:11

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