Regression: Optix denoiser produces significant artifacts on materials with subsurface scattering #97792

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James Kurian · 2022-05-03T07:05:39+02:00

James Kurian commented

2022-05-03 07:05:39 +02:00

System Information
Operating system: Windows-10-10.0.19044-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 512.59

Blender Version
Broken: version: 3.1.2, branch: master, commit date: 2022-03-31 17:40, hash: cc66d1020c
Worked: 3.0.1

Short description of error
Optix denoiser produces grainy artifacts on materials with subsurface scattering

Exact steps for others to reproduce the errorOptix_Artifact.blend

Instructions from new blend file:

Delete cube
Add default torus
Change renderer to Cycles (CyclesX)
Enable Viewport denoising
Set Denoiser to "Optix"
Set passes to "Albedo and Normal" (bug occurs with "Albedo" only as well)
Change Viewport Shading to Render Preview
Click on Torus and press numpad "." to zoom into torus.
Add Material to torus.
Set base color to hex value of "E748DE"

Set subsurface to "0.01"

For the included blend file, simply open it and change viewport shading to "render preview"

The artifact should now be visible. Sometimes, shading the torus smooth can make it easier to see. For me, it is visible in the superior and distal portion of the torus, with respect to the viewport. I have attached a screenshot. The artifact occurs in actual renders as well, not just in the viewport. It does not seem to occur in all colors, but only in some of them. Perhaps it is just harder to see with some colors than others. It does not occur if the Optix denoiser passes are set to "none." The same issue occurs in Linux as well (I tested on Ubuntu).

**System Information** Operating system: Windows-10-10.0.19044-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 3080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 512.59 **Blender Version** Broken: version: 3.1.2, branch: master, commit date: 2022-03-31 17:40, hash: `cc66d1020c` Worked: 3.0.1 **Short description of error** Optix denoiser produces grainy artifacts on materials with subsurface scattering **Exact steps for others to reproduce the error**[Optix_Artifact.blend](https://archive.blender.org/developer/F13048278/Optix_Artifact.blend) ![Screenshot 2022-05-02 234016.png](https://archive.blender.org/developer/F13048330/Screenshot_2022-05-02_234016.png) Instructions from new blend file: - Delete cube - Add default torus - Change renderer to Cycles (CyclesX) - Enable Viewport denoising - Set Denoiser to "Optix" - Set passes to "Albedo and Normal" (bug occurs with "Albedo" only as well) - Change Viewport Shading to Render Preview - Click on Torus and press numpad "." to zoom into torus. - Add Material to torus. - Set base color to hex value of "E748DE" # Set subsurface to "0.01" For the included blend file, simply open it and change viewport shading to "render preview" The artifact should now be visible. Sometimes, shading the torus smooth can make it easier to see. For me, it is visible in the superior and distal portion of the torus, with respect to the viewport. I have attached a screenshot. The artifact occurs in actual renders as well, not just in the viewport. It does not seem to occur in all colors, but only in some of them. Perhaps it is just harder to see with some colors than others. It does not occur if the Optix denoiser passes are set to "none." The same issue occurs in Linux as well (I tested on Ubuntu).

James Kurian commented

2022-05-03 07:05:39 +02:00

Added subscriber: @James-Kurian

Philipp Oeser commented

2022-05-03 13:00:41 +02:00

Added subscriber: @lichtwerk

Philipp Oeser commented

2022-05-03 13:00:41 +02:00

Changed status from 'Needs Triage' to: 'Confirmed'

Philipp Oeser commented

2022-05-03 13:00:41 +02:00

Can confirm, will set to High prio since this looks like a regression.

Philipp Oeser changed title from ~~Optix denoiser produces significant artifacts on materials with subsurface scattering~~ to Regression: Optix denoiser produces significant artifacts on materials with subsurface scattering

2022-05-03 13:01:02 +02:00

Brecht Van Lommel commented

2022-05-03 18:22:06 +02:00

Added subscriber: @brecht

Brecht Van Lommel commented

2022-05-03 18:22:06 +02:00

Changed status from 'Confirmed' to: 'Archived'

Brecht Van Lommel closed this issue

2022-05-03 18:22:06 +02:00

Brecht Van Lommel commented

2022-05-03 18:22:06 +02:00

We changed the denoising albedo pass in eaa4cda to improve results in other cases, which lead to this.

The effective change to the denoising albedo in this file is slight, but it happens to cross some arbitrary threshold where the OptiX denoiser starts to incorrectly interpret some noise as features.

Similar artifacts in older Blender versions if you use a brighter base color, or is avoided in newer Blender versions with a darker base color. I don't think there's anything we can do here to fundamentally improve things in Cycles. The AI denoiser is just guessing, and trying to tune the passes for this .blend file will make other cases worse.

We changed the denoising albedo pass in eaa4cda to improve results in other cases, which lead to this. The effective change to the denoising albedo in this file is slight, but it happens to cross some arbitrary threshold where the OptiX denoiser starts to incorrectly interpret some noise as features. Similar artifacts in older Blender versions if you use a brighter base color, or is avoided in newer Blender versions with a darker base color. I don't think there's anything we can do here to fundamentally improve things in Cycles. The AI denoiser is just guessing, and trying to tune the passes for this .blend file will make other cases worse.

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Regression: Optix denoiser produces significant artifacts on materials with subsurface scattering #97792

Set subsurface to "0.01"