Dark Intersections when using Cycles Random Walk SSS #85202

Closed
opened 2021-01-29 16:42:09 +01:00 by Joe Williamsen · 5 comments

System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce RTX 2070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 461.09

Blender Version
Broken: version: 2.91.2, branch: master, commit date: 2021-01-19 16:15, hash: 5be9ef4177
Worked: Not working in 2.83, 2.91, 2.92, or 2.93.

Short description of error
This may be expected/known behavior, but I'm seeing some really odd dark "seams" when portions of a mesh with Random Walk SSS intersect themselves (in this case, a character's knee) - rendered in Cycles.

The "spread" is directly related to Subsurface setting in the Principled BSDF shader.

When using Burley SSS these artifacts do not appear. Tried with CUDA, OPTIX, CPU, etc

Random Walk.jpg

Exact steps for others to reproduce the error
Open the attached Blend, go to rendered view. Both models have identical materials with the exception of the SSS calculation mode.

SSS Bug1.zip

**System Information** Operating system: Windows-10-10.0.18362-SP0 64 Bits Graphics card: GeForce RTX 2070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 461.09 **Blender Version** Broken: version: 2.91.2, branch: master, commit date: 2021-01-19 16:15, hash: `5be9ef4177` Worked: Not working in 2.83, 2.91, 2.92, or 2.93. **Short description of error** This may be expected/known behavior, but I'm seeing some really odd dark "seams" when portions of a mesh with Random Walk SSS intersect themselves (in this case, a character's knee) - rendered in Cycles. The "spread" is directly related to Subsurface setting in the Principled BSDF shader. When using Burley SSS these artifacts do not appear. Tried with CUDA, OPTIX, CPU, etc ![Random Walk.jpg](https://archive.blender.org/developer/F9604051/Random_Walk.jpg) **Exact steps for others to reproduce the error** Open the attached Blend, go to rendered view. Both models have identical materials with the exception of the SSS calculation mode. [SSS Bug1.zip](https://archive.blender.org/developer/F9604060/SSS_Bug1.zip)
Author

Added subscriber: @Joe_W

Added subscriber: @Joe_W

Added subscriber: @DarkKnight

Added subscriber: @DarkKnight

I think this is the same as #81602 Its a limitation in the algorithm

I think this is the same as #81602 Its a limitation in the algorithm
Author

Yeah - that looks like the same thing. So, this can probably be closed.

Yeah - that looks like the same thing. So, this can probably be closed.

Closed as duplicate of #81602

Closed as duplicate of #81602
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Reference: blender/blender#85202
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