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Mantaflow: Slight jitter of the Domain object. Gas.
Closed, ResolvedPublic

Description

System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce GTX 1070 Ti/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 442.19

Blender Version
Broken: version: 2.82 (sub 7), branch: master, commit date: 2020-02-12 16:20, hash: rB77d23b0bd76f

Short description of error
Most likely, jitter occurs when the adaptive Domain begins to trim the excess voxels. When extra voxels are removed, the noise information becomes incorrect and the noise shows artifacts.



And another test.

Event Timeline

Yuriy (Faraday) updated the task description. (Show Details)
Yuriy (Faraday) added a comment.EditedFeb 26 2020, 10:13 AM

I found out that jitter only appears with Noise enabled in the Domain settings. Without noise, baked smoke does not tremble. In the video, the result is first with noise, then without noise.
I uploaded the cache. Only 180-190 frames.

I would suggest trying to strip this file from any unnecessary things such as camera animation.
Preferably also simplifying simulation. With file as is now it may be impossible to debug.

Most likely, jitter occurs when the adaptive Domain begins to trim the excess voxels. When extra voxels are removed, the noise information becomes incorrect and the noise shows artifacts.



And another test.

Richard Antalik (ISS) changed the task status from Needs Triage to Needs Information from User.Feb 26 2020, 6:40 PM

@Yuriy Thanks for simplified case. Can you also point out frames to look for? I am looking at cube render and don't see anything extraordinary

It would be better for developer to render only say 10 frames not whole animation

Richard Antalik (ISS) changed the task status from Needs Information from User to Confirmed.Mar 11 2020, 8:02 PM

I think this issue is related to T72253. A detailed explanation can be found over there.

In short: The solution is to use a smaller Empty Space value. And since the adaptive domain is being used, the Threshold (Adaptive Domain panel) also needs to be smaller.
Otherwise voxels with smoke will be considered "empty" too soon.