Strange artifacting with subsurface scattering objects #95971

New Issue

System Information
Operating system: macOS Monterey
Graphics card: Apple Silicon M1

Blender Version
Broken: 2.93 LTS, 3.0.1
Worked: 3.2.0 Alpha

Short description of error
There is some very strange artifacting in Eevee with subsurface scattering materials. It looks like a pattern of tiny black circles. The more samples you use, the worse it gets. Seems to be fixed in 3.2.0, but still affects the current official build on the Blender website.

Image rendered with 32 samples:

Image rendered with 1,024 samples:

Exact steps for others to reproduce the error
Open the file. Switch to "rendered" view. You can also render out the image normally. The more samples the scene accumulates, the worse it gets. Rendering with 32 samples looks better than 2,000 samples for example. Beyond that, I'm not sure how to reproduce this issue.

buggySSS.zip

Note
The file may ask you to load a script. It is a remnant from an addon of mine. Simply deny it as it is not important for the scene.

**System Information** Operating system: macOS Monterey Graphics card: Apple Silicon `M1` **Blender Version** Broken: 2.93 LTS, 3.0.1 Worked: 3.2.0 Alpha **Short description of error** There is some very strange artifacting in Eevee with subsurface scattering materials. It looks like a pattern of tiny black circles. The more samples you use, the worse it gets. Seems to be fixed in 3.2.0, but still affects the current official build on the Blender website. Image rendered with 32 samples: ![buggySSS_32samples.jpg](https://archive.blender.org/developer/F12883450/buggySSS_32samples.jpg) Image rendered with 1,024 samples: ![buggySSS_1024samples.jpg](https://archive.blender.org/developer/F12883452/buggySSS_1024samples.jpg) **Exact steps for others to reproduce the error** Open the file. Switch to "rendered" view. You can also render out the image normally. The more samples the scene accumulates, the worse it gets. Rendering with 32 samples looks better than 2,000 samples for example. Beyond that, I'm not sure how to reproduce this issue. [buggySSS.zip](https://archive.blender.org/developer/F12883454/buggySSS.zip) **Note** The file may ask you to load a script. It is a remnant from an addon of mine. Simply deny it as it is not important for the scene.

Added subscriber: @Caden-Mitchell

Added subscriber: @Alaska

Changed status from 'Needs Triage' to: 'Needs User Info'

There is some very strange artifacting in Eevee with subsurface scattering materials. It looks like a pattern of tiny black circles. The more samples you use, the worse it gets. Seems to be fixed in 3.2.0, but still affects the current official build on the Blender website.

If the issue has been fixed in a future release of Blender, then it is considered "resolved" unless the problem is there in a "LTS" version of Blender. Does this issue occur in a LTS version of Blender? ("LTS" versions of Blender include the latest versions of 2.83 and 2.93 - You can download them from here: https://www.blender.org/download/lts/)

Note: I am asking you if this happens as I can not test it myself as I can not reproduce the issue on my computer.

> There is some very strange artifacting in Eevee with subsurface scattering materials. It looks like a pattern of tiny black circles. The more samples you use, the worse it gets. Seems to be fixed in 3.2.0, but still affects the current official build on the Blender website. If the issue has been fixed in a future release of Blender, then it is considered "resolved" unless the problem is there in a "LTS" version of Blender. Does this issue occur in a LTS version of Blender? ("LTS" versions of Blender include the latest versions of 2.83 and 2.93 - You can download them from here: https://www.blender.org/download/lts/) Note: I am asking you if this happens as I can not test it myself as I can not reproduce the issue on my computer.

In #95971#1312314, @Alaska wrote:

There is some very strange artifacting in Eevee with subsurface scattering materials. It looks like a pattern of tiny black circles. The more samples you use, the worse it gets. Seems to be fixed in 3.2.0, but still affects the current official build on the Blender website.

If the issue has been fixed in a future release of Blender, then it is considered "resolved" unless the problem is there in a "LTS" version of Blender. Does this issue occur in a LTS version of Blender? ("LTS" versions of Blender include the latest versions of 2.83 and 2.93 - You can download them from here: https://www.blender.org/download/lts/)

Note: I am asking you if this happens as I can not test it myself as I can not reproduce the issue on my computer.

Confirmed. Affects Blender 2.93.8 LTS in viewport and final render. This is the native version for Apple Silicon M1 (ARM64).

Again, this seems to be patched in 3.2.0 Alpha. It's either been fixed, or is a byproduct of some rewritten code.

> In #95971#1312314, @Alaska wrote: >> There is some very strange artifacting in Eevee with subsurface scattering materials. It looks like a pattern of tiny black circles. The more samples you use, the worse it gets. Seems to be fixed in 3.2.0, but still affects the current official build on the Blender website. > > If the issue has been fixed in a future release of Blender, then it is considered "resolved" unless the problem is there in a "LTS" version of Blender. Does this issue occur in a LTS version of Blender? ("LTS" versions of Blender include the latest versions of 2.83 and 2.93 - You can download them from here: https://www.blender.org/download/lts/) > > Note: I am asking you if this happens as I can not test it myself as I can not reproduce the issue on my computer. Confirmed. Affects Blender 2.93.8 LTS in viewport and final render. This is the native version for Apple Silicon `M1` (ARM64). ![Screen Shot 2022-02-23 at 9.49.30 AM.png](https://archive.blender.org/developer/F12884349/Screen_Shot_2022-02-23_at_9.49.30_AM.png) Again, this seems to be patched in 3.2.0 Alpha. It's either been fixed, or is a byproduct of some rewritten code. ![Screen Shot 2022-02-23 at 9.51.30 AM.png](https://archive.blender.org/developer/F12884352/Screen_Shot_2022-02-23_at_9.51.30_AM.png)

Minor update: setting Properties > Render > Subsurface Scattering > Jitter Threshold to a higher value will distort the artifacts. Bug may be related to jitter sampling?

Minor update: setting `Properties > Render > Subsurface Scattering > Jitter Threshold` to a higher value will distort the artifacts. Bug may be related to jitter sampling?

Added subscriber: @mano-wii

Sorry to bother you @mano-wii , but apparently you have an M1 Mac.
Are you able to bisect to find out what fixed this issue in Master then add it to the list of fixes that should be included in the next release of 2.93.X?

That's assuming you can reproduce this issue on your hardware.

Sorry to bother you @mano-wii , but apparently you have an M1 Mac. Are you able to bisect to find out what fixed this issue in Master then add it to the list of fixes that should be included in the next release of 2.93.X? That's assuming you can reproduce this issue on your hardware.

Added subscriber: @PratikPB2123

Can not reproduce either (tested on 3.0.1)

Graphics card : AMD Radeon(TM) 535 ATI Technologies .```

Can not reproduce either (tested on 3.0.1) ```Operating system : Windows-10-10.0.18362-SP0 64 Bits Graphics card : AMD Radeon(TM) 535 ATI Technologies .```

Changed status from 'Needs User Info' to: 'Needs Developer To Reproduce'

I can confirm the problem on MAC M1.
Apparently the problem was fixed by cfa53e0fbe.
I don't know exactly what in that commit may have resulted in the fix. (Maybe this is a compiler bug?)

Good to know that this problem is no longer seen in recent versions, but since it only occurs on MAC M1 and the commit that resolved it is a large refactor that cannot be backported, I don't think it's worth investigating further a fix for this problem.

But I'll leave the final decision to the #eevee_viewport team.

I can confirm the problem on MAC `M1`. Apparently the problem was fixed by cfa53e0fbe. I don't know exactly what in that commit may have resulted in the fix. (Maybe this is a compiler bug?) Good to know that this problem is no longer seen in recent versions, but since it only occurs on MAC `M1` and the commit that resolved it is a large refactor that cannot be backported, I don't think it's worth investigating further a fix for this problem. But I'll leave the final decision to the #eevee_viewport team.

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Strange artifacting with subsurface scattering objects #95971