VRAY7 GPU // CAUSTICS - Animation issue

[nicolas_fuminier]

Hello,


We're continuing our experiments in the studio, focusing almost exclusively on the caustics feature.

The first (and main) problem we've encountered since the vray_adv_70001_max2025_x64_32809 beta build (official vray_adv_70002_max2025_x64 release have the same issue) is that we can no longer render animated scenes with caustics inside.
I'm in the middle of a test set and haven't done all the cross-testing I'd like, but from what I understand at the moment, this problem doesn't exist on the vray_adv_70001_max2025_x64_32796 build.

Our computers (solo, group, local, network, via max, via a render manager etc...) are unable to render two frames with caustics in a row with the last two builds above.
Either Max simply crashes as soon as it tries to render the second frame (when the scene is rendered on a single computer) when changing frame.
Or Max takes 6 to 7 hours (I did said hours, it's not a mistake) to precalculate the caustics of the second frame for a frame that normally takes 30 to 40 seconds to precalculate the caustics pass (when the scene is rendered via a Pulze-type render manager).

To sum up: Max is very good at rendering a single frame of an image sequence with caustics. As soon as he moves on to the second frame. It either crashes, or takes an improbable amount of time to calculate the prepass.

vray_adv_70001_max2025_x64_32796 build has other issues the news builds don't have ... but at least we can render animated sequence with this one.


I might be wrong somewhere, it's difficult to be sure of my info since everything is moving fast between builds but I hope I've explained it well enough for you to find something to correct.

Best,
Nicolas

[nicolas_fuminier]

Continuing our tests by navigating between builds and different concerns, overall we have :

- Intensity consistency problems in caustics between different frames (calculated with the same computer to make sure it's not due to different configurations)
- Problems setting up caustics in scenes. They have a strong tendency to simply disappear (or half disappear) from the render depending on: the size of the light in relation to the size of the scene, the intensity of the light, the distance of the light from the subject, the distance of the camera from the subject... In short, caustics are displayed or not displayed according to rules that are difficult to master and understand. Even more so in an image sequence (moving light, moving camera ..).
- There are always problems of finesse on soft, sparse caustics surfaces, without having to bombard millions of rays. Combine this with the fact that caustics light “dots” don't seem to be cleaned by denoisers (Nvidia denoiser at least), which forces denoising in post-production.

We're stopping our tests for GPU caustics for the time being, as we're encountering too many problems to be able to test more different scenes / setup.
We're currently going back to CPU cautics waiting for the next updates.
Hopefully, we'll have some new builds to test that will improve all the above points.

Best,
Nicolas

[tanya_to]

Hey nicolas_fuminier thanks for the feedback. I'm currently testing a simple setup with animated camera/animated object with the official release build and it's not crashing on the second frame.

Problems setting up caustics in scenes. They have a strong tendency to simply disappear (or half disappear) from the render depending on: the size of the light in relation to the size of the scene, the intensity of the light, the distance of the light from the subject, the distance of the camera from the subject... In short, caustics are displayed or not displayed according to rules that are difficult to master and understand. Even more so in an image sequence (moving light, moving camera ..).

This should be fixed in the release build. Can you share a scene so we can take a look into it?

[nicolas_fuminier]

Hello tanya_to

Thanks for the feedback,
If it work in animation sequence with the release build on your side, it my be scene related on my side. I'll try to share a sample of my scene if possible and also test with a much more simpler scene on my side.

Good news for the setup fix,

Best Nicolas

[tanya_to]

Hey nicolas_fuminier I've managed to reproduce the issue with animation not working with caustics and we will fix this. I was testing with a scene saved with an old version, that's why it worked in my tests. Sorry for the inconvenience.

[nicolas_fuminier]

Hello tanya_to

I saw many improvement for Caustics from lasts nightlies, I'll try them as soon as possible.

Bug fixes:
(*) V-Ray GPU: Animation with caustics enabled causes a crash on second frame; (VGPU-6660)

Thanks for the work,
Best,
Nicolas