Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] I need help! => Topic started by: johan belmans on 2024-11-05, 17:59:53

Title: Volumetric grid: flicker in animation
Post by: johan belmans on 2024-11-05, 17:59:53
I have an issue when rendering an animation with Corona volume grid objects. They flicker over time in the rendered result. The vdb file does not contain any animation.
I rendered the animation with Path tracing as the primary solver and secondary solver and I rendered it with Path tracing and UHD cache (with a pre-calculated cache (every 5 frames). In both cases it flickers.
The lights Samples Multiplier has a value of 8.0
There is no material assigned to the clouds. The shading settings can be found in the attachment.
Any help would be welcome.

edit: every frame is rendered with 20 passes

Title: Re: Volumetric grid: flicker in animation
Post by: TomG on 2024-11-05, 18:27:03
TBH there really does seem to be some animation there, perhaps in the step size, or quality, or perhaps in the absorption, because the pattern repeats - it starts detailed and dense, then fades over three frames, then holds for three frames, then jumps to yet less detailed and dense and holds for three frames, then goes and repeats the exact same cycle. Such a specific set of repeats seems unlikely to come from some render engine error. Can you open a ticket and send in the scene?
Title: Re: Volumetric grid: flicker in animation
Post by: TomG on 2024-11-05, 18:29:35
Or you could try adjusting the "Animation" parameters and see if the flicker effect changes along with it, e.g. don't use repeat since this is definitely a repeating cycle :) And your length is set to 9, which is.... 3 times 3, and that's the length of the repeat in your video, 9 frames.
Title: Re: Volumetric grid: flicker in animation
Post by: pokoy on 2024-11-05, 20:34:11
Do you happen to use a vdb file that has its resolution or version included as a numeric string in the filename at the end of the filename?
Something like '...v1', '...v2', '...v3' would cause the loader to interpret that as a sequence and repeat or loop it according to the vdb object's setting.
Title: Re: Volumetric grid: flicker in animation
Post by: johan belmans on 2024-11-06, 19:23:29
Thanks for the the help, the issue is solved. There was a numeric string at the end filename of the different VDBs in the same directory. I added a letter at the end of the file names but still the vdb's were loaded as a sequence in MAX. The easiest solution was one single vdb in a directory.
Title: Re: Volumetric grid: flicker in animation
Post by: Nejc Kilar on 2024-11-07, 13:30:30
Glad to hear you've resolved the issue and thank you for letting us know what went awry :)
Title: Re: Volumetric grid: flicker in animation
Post by: NazarVitkovskyi on 2025-02-10, 10:33:45
Hi @johan belmans

can we use the video you shared to update our Help Center article about fixing flickering in animation?
Title: Re: Volumetric grid: flicker in animation
Post by: johan belmans on 2025-02-11, 10:33:46
Yes, sure, no problem.