Detailed destroyed behind glass using denoiser

[lightwriter]

Sorry for the error in the title. It should be: "Details destroyed behind glass using denoiser"

Good afternoon,

I have to animate a scene, so I have to make some compromises. I set the noise limit to 0,05, in Light Cache the subdivs are 1250 and retrace is 8,0.
I'm using V-ray raw image file, and rendering through Batch Render, since it allows me to have better noise control in animations using VDenoise.

However, even using the mild Preset in Denoising Quality the details of the wall behind two panes of glass are obliterated (the glass panes make a 90 degree angle between them).

I saw this post: https://forums.chaosgroup.com/forum/...iser-and-glass, but since it's an animation, there is no way I can use two denoiser passes and blend them together as a workaround - my deadlines don't allow it.

I also read this post: https://forums.chaosgroup.com/forum/...hind-the-glass, where Peter.Chaushev says to make sure that:

• the glass material's reflection does not affect all channels
• the glass material's refraction affects all channels

However, he also says this only works with CPU (and I need to use the hybrid method to have the maximum speed). Nevertheless, I was having artifacts behind the glass, and the only way to solve them was to check Reflect on back side and Affect all channels in Reflect and Refract, regarding the glass material.

Software used: 3ds Max 2021.3, V-ray 5 hotfix 2, latest Nvidia Studio drivers.

Is there something else I can do?

[hermit.crab]

Not much, I'm afraid. To diminish the blurry effect, you may reduce the opacity of the denoiser element for that particular part of the image (mask it) in post.

[seandunderdale]

I had to stop using denoiser on GPU for my automotive work as it used to destroy the interiors, since there sat behind glass. The issue is fixed if you render with glass primary vis off, but sometimes that isnt part of the workflow, so I had to drop denoise.

[lightwriter]

Not much, I'm afraid. To diminish the blurry effect, you may reduce the opacity of the denoiser element for that particular part of the image (mask it) in post.

That's unfortunate, but thanks for the answer. When you say to reduce the opacity of the denoiser element for that particular part of the image (the glass), how can I do it? with render elements?

[hermit.crab]

Yes, with the Denoiser pass. When compositing, where the Denoiser is on top of the RGB channel, lower its opacity (mask it for the glass only as well).

[Micha]

Did I understand right - this will make that the undenoised scene is shown through the glass or?

[hermit.crab]

Micha Yes, so as to get a bit of the detail back.

[Micha]

OK, this means also noise will come back. I would prefer a stable quality like known from the CPU mode.