Inconsistent noise in animation

[matus.nedecky]

Hello, newbie in animations. This scene has some moving plants, the car is static. This is a screenshot from 2 following frames (50 and 51). The noise is clearly visible on right side in one frame, and on left side on another frame. This is flickering when animation is played.
Any ideas?

[matus.nedecky]

And nope, no area render was used.

[maru]

This looks very strange. Is this rendered locally or is it some kind of network/distributed render?

[matus.nedecky]

This is from RebusFarm. But I can confirm this also happens on  local machine with a single CPU (AMD RYZEN 9 7950X).

[romullus]

Could it be adaptive light solver? I remember similar issues with it in early days. Go to developer settings in render setup and uncheck adaptive light solver, see if it helps.

[maru]

Are you 100% sure that it also happens when rendering on a single local machine?

Could you share the material setup for the carpaint? Asking because it looks like the noise is pretty much uniform on all other objects/materials.

Lastly, as Romullus noted, this could be one of the adaptive samplers/solvers. You could try the following:
1. Enable Development/experimental stuff rollout - https://support.chaos.com/hc/en-us/articles/4528523195537
2. Go to the Performance tab and scroll down to Development/experimental stuff
3. Under "Lights" find "Adaptive light solver" and disable it - check if the issue is still there; if yes - enable the option back!
4. Also under "Lights" find "Enviro sampler" and change it to "NormalDep Compensated" - check if the issue is still there; if yes - switch back to "Adaptive sampler"!

[matus.nedecky]

It also happens on static renders in other scenes, but I never cared because if it's not random within animation frames, it's barely noticeable.
Material is basic from Corona material library, just had to make the flakes smaller.
I'll follow your suggestions once my other animation is finished.

[matus.nedecky]

Are you 100% sure that it also happens when rendering on a single local machine?

Could you share the material setup for the carpaint? Asking because it looks like the noise is pretty much uniform on all other objects/materials.

Lastly, as Romullus noted, this could be one of the adaptive samplers/solvers. You could try the following:
1. Enable Development/experimental stuff rollout - https://support.chaos.com/hc/en-us/articles/4528523195537
2. Go to the Performance tab and scroll down to Development/experimental stuff
3. Under "Lights" find "Adaptive light solver" and disable it - check if the issue is still there; if yes - enable the option back!
4. Also under "Lights" find "Enviro sampler" and change it to "NormalDep Compensated" - check if the issue is still there; if yes - switch back to "Adaptive sampler"!

The thing is not the amount of noise, which is present also elsewhere. If it was consistent overal, I would just add passes. The issue is the noise is just in certain areas, which are rectangular. almost like it was rendered with buckets in old Vray and these areas randomly change between frames.
Added the screenshot of the car material

[romullus]

I noticed that your carpaint material setup is incorrect. I'm not sure if that could have anything to do with the noise issue, but maybe it's worth trying to fix it and see if that helps somehow. Could you try to arrange nodes like in my attached image and render few frames?

[maru]

The thing is not the amount of noise, which is present also elsewhere. If it was consistent overal, I would just add passes. The issue is the noise is just in certain areas, which are rectangular. almost like it was rendered with buckets in old Vray and these areas randomly change between frames.

That's exactly why I recommended checking the adaptive sampler/solver. They are adaptive, which means that they can treat different areas of the scene differently. Of course getting different noise levels like in your case is not expected, so if you confirm that disabling one of them helps, then it would be a bug.

[matus.nedecky]

Did a few tests (also adjusted the material as advised), but what really helped to solve this was turning off the adaptive solver. Now the car is consistently noisy.
Thank you

[matus.nedecky]

Hm maybe I sent the reply too soon.
The issue persists.

[matus.nedecky]

Seems both options help to solve the issue.

[maru]

Could you please archive this scene with all assets (File > Archive), or at least the part of it where the problem can be reproduced, and send it to us at https://support.chaos.com/hc/en-us/requests/new ?

We would like to investigate what might be wrong and possibly report it as a bug.

Thank you in advance!

[matus.nedecky]

Could you please archive this scene with all assets (File > Archive), or at least the part of it where the problem can be reproduced, and send it to us at https://support.chaos.com/hc/en-us/requests/new ?

We would like to investigate what might be wrong and possibly report it as a bug.

Thank you in advance!

Will do, thank you for the support