Weird flickering in animation with volumetric material

[3dkobi]

Hi guys,
I'm rendering an animation and I'm having a weird flickering in the volumetric material.
At the attached examples, look at the letter "A", at the bottom right, there's a weird spot that is changing during frames and actually it doesn't suppose to be there at all.
Any idea what can cause this ?

Kobi

[Nejc Kilar]

I think you should give PT PT a try for a scene like this - might even render a bit faster without the UHD cache precalc phase.

That said, whenever I get flickering going on the first thing I try is to up the UHD precision from 1 to 2 sometimes even 4.

[3dkobi]

I think you should give PT PT a try for a scene like this - might even render a bit faster without the UHD cache precalc phase.

That said, whenever I get flickering going on the first thing I try is to up the UHD precision from 1 to 2 sometimes even 4.

Thanks for the info, I'll make some more tests and report here with the results

[3dkobi]

So I did some tests...
I raised the UHD precision to 2 - nothing changed, still flickering.
I raised the UHD precision to 4 - nothing changed, still flickering.
I raised the UHD precision to 10 - nothing changed, still flickering, and render times went down a bit. Very strange....
I changed the GI to PT - nothing changed, still flickering.

I also tried to use the 4K cache (experimental) but with no lack

Any other idea why I get this flickering ?

[romullus]

I can think of two reasons - intersecting geometry and shading error caused by automatic boolean operation (fracturing). Neither of them has anything to do with UHD cache filckering and it's not something that can be fixed in render settings.

[3dkobi]

I can think of two reasons - intersecting geometry and shading error caused by automatic boolean operation (fracturing). Neither of them has anything to do with UHD cache filckering and it's not something that can be fixed in render settings.

Thanks, I'll check those things