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Maniphest T97193

SSS Bug in render Cycles (principled shader) blender version 3.1.2
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Description

System Information
Operating system: Windows-10-10.0.19044-SP0 64 Bits
Graphics card: GeForce RTX 2080 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 456.71

Blender Version
Broken: 3.0 - 3.1.2, commit date: 2022-03-31 17:40, hash: rBcc66d1020c3b
Worked: 2.93.5

Short description of error

Hello, I think I have possibly found a bug with the sss in Cycles rendering, I have strange artifacts like the appearance of bands as soon as I activate the sss in cycles. In eevee it seems to work.
As soon as I disactivate the sss, everything is ok.
I tried to export the object in obj for cleaning it but nothing worked.

The SSS mask and the textures are from SubstancePainter.

Exact steps for others to reproduce the error

  • import the pbr texture
  • add an image texture for SSS
  • connect it to SSS slot in principled shader.>Artifact
  • Disconnect it >Good

If you can tell me if it's a bug or if there's a new way to use sss, that'll be fine.

I am attaching the files to show you the problem.

Thanking you in advance.

Best Regards

debug demo_Blender 2.93.blend915 KBDownload

debug demo_Blender 3.12.blend920 KBDownload

debug demo_Blender 3.12.blend920 KBDownload

Event Timeline

Eric Seigaud (LeDucAtreide) created this task.Apr 9 2022, 10:52 AM
Germano Cavalcante (mano-wii) updated the task description. (Show Details)Apr 12 2022, 4:21 PM
Germano Cavalcante (mano-wii) closed this task as Archived.Apr 12 2022, 4:53 PM
Germano Cavalcante (mano-wii) added a subscriber: Germano Cavalcante (mano-wii).

Opening the 2.93 file in blender version 2.93, I could notice that the SSS type is not explicitly defined:

This tells me that the file was made in a newer version and then opened in 2.93 thus losing information.
This situation is not considered a bug.
Simplifying the file often helps to identify this.

Eric Seigaud (LeDucAtreide) added a comment.EditedApr 12 2022, 6:34 PM

Hello,

yes it's right the model was made in the 3.1.2 version. It's why it's seems work in 2.93 in fact there is no sss in 2.93. If I'll use random walk in 2.93 it work with a little artefact but less than 3.1.2 (see picture)

I ll don't use often the sss,I'll just see if I'll change in 3.1.2 "random walk to christensen-burley the SSS banding disappear but the quality is less.
Random walk make banding or artefact
Random walk fixed radius made banding and artefact also.

In 3.93 random walk the sss color red work with little artefacts
In 3.1.2 random walk the sss color red appear white with big artefacts.
In 3.1.2 random walk fixed radius the sss color red appear red with big artefacts.

Thanks for your help.

Best regards.