Caustic Sampler not rendering on GPU

emu42

I am trying to render one of my scenes with the Caustic Sampler enabled. But it will only render on the CPU and put messages like these in the log:

2022-12-17 12:24:19.051 [WARNING] :: ..\..\..\..\..\src\pluginsource\DzIrayRender\dzneuraymgr.cpp(369): Iray [ERROR] - IRAY:RENDER ::   1.6   IRAY   rend error: CUDA device 0 (NVIDIA GeForce RTX 3090): Kernel [15] (LensTraceSr       ) failed after 6.459s
2022-12-17 12:24:19.052 [WARNING] :: ..\..\..\..\..\src\pluginsource\DzIrayRender\dzneuraymgr.cpp(369): Iray [ERROR] - IRAY:RENDER ::   1.6   IRAY   rend error: CUDA device 0 (NVIDIA GeForce RTX 3090): unspecified launch failure (while launching CUDA renderer in <internal>:951)
2022-12-17 12:24:19.052 [WARNING] :: ..\..\..\..\..\src\pluginsource\DzIrayRender\dzneuraymgr.cpp(369): Iray [ERROR] - IRAY:RENDER ::   1.6   IRAY   rend error: CUDA device 0 (NVIDIA GeForce RTX 3090): Failed to launch renderer
2022-12-17 12:24:19.052 [WARNING] :: ..\..\..\..\..\src\pluginsource\DzIrayRender\dzneuraymgr.cpp(369): Iray [ERROR] - IRAY:RENDER ::   1.4   IRAY   rend error: CUDA device 0 (NVIDIA GeForce RTX 3090): Device failed while rendering
2022-12-17 12:24:19.052 [WARNING] :: ..\..\..\..\..\src\pluginsource\DzIrayRender\dzneuraymgr.cpp(369): Iray [WARNING] - IRAY:RENDER ::   1.4   IRAY   rend warn : CUDA device 0 (NVIDIA GeForce RTX 3090) is no longer available for rendering.
2022-12-17 12:24:19.055 [WARNING] :: ..\..\..\..\..\src\pluginsource\DzIrayRender\dzneuraymgr.cpp(369): Iray [WARNING] - IRAY:RENDER ::   1.4   IRAY   rend warn : All available GPUs failed.
2022-12-17 12:24:19.056 [WARNING] :: ..\..\..\..\..\src\pluginsource\DzIrayRender\dzneuraymgr.cpp(369): Iray [WARNING] - IRAY:RENDER ::   1.4   IRAY   rend warn : No devices activated. Enabling CPU fallback.

Is this a known issue? Does anyone have an idea how to work around this?

I am using DS 4.21.0.5 and nVidia driver 527.56.

 

feldarzt

I guess bumping a week-old topic isn’t necro-posting...

I was struck by the same issue. Nothing was changed, installed, or uninstalled in DS. After rendering another scene normally, I updated the scene, making the next frame of the story, basically moving a character and adding a spotlight (cylinder-shaped, 5 in diameter, 320 in length). DS started rendering the updated scene as usual, but then stopped after a few hundred iterations. It still renders normally with Caustic Sampler turned off, but not with it turned on; which sucks because there are some water drops and streaks in the scene.

I’m trying to attach the relevant part of the log to the message, but it looks like the forum doesn't want to accept it. Let's see if it's actually attached.

The driver version was initially 526.98 Game Ready, then I updated it to 527.56 Studio. No luck, though.

Help :’(

-
Nah, can't attach a file. It gets stuck at the "uploading" stage.

feldarzt

UPD:
It seems that Max Path Length parameter, whatever it is, has something to do with the issue. The bigger its value, the more iterations the GPUs do. With about 600 iterations while Max Path Length = 18 to about 3200 iterations while it = -1 (unlimited?)

Still, with max iterations set to 6000, it is about halfway through the full rendering. And it's an error anyway.

Richard Haseltine

feldarzt said:

UPD:
It seems that Max Path Length parameter, whatever it is, has something to do with the issue. The bigger its value, the more iterations the GPUs do. With about 600 iterations while Max Path Length = 18 to about 3200 iterations while it = -1 (unlimited?)

Max path Length is how many times, at most, a path can bounce off a surface. Once the limit is hit the current state is taken as final, even if it would otherwise have enough energy (or however it isa ssessed) to go on changing through some more bounces. It does sound as if you scene has some very shiny surfaces, so that it takes a long time to decay to the point that Iray consdiers it done.

Still, with max iterations set to 6000, it is about halfway through the full rendering. And it's an error anyway.

feldarzt

Richard Haseltine said:

Max path Length is how many times, at most, a path can bounce off a surface. Once the limit is hit the current state is taken as final, even if it would otherwise have enough energy (or however it is assessed) to go on changing through some more bounces. It does sound as if you scene has some very shiny surfaces, so that it takes a long time to decay to the point that Iray consdiers it done.

Yes, the scene does have some amount of shiny/watery surfaces, namely three geoshells (two of them with displacement) to create the water effects like drops and streaks, some translucent embossed glass, and a bit of fog... So, is it possible that, at some point, Iray is being overloaded with all those caustic stuff and drops the rendering? This idea kinda sounds realistic, but... hey, it's still a pair of pretty powerful GPUs.
Is there a way to fix this Caustic Sampler issue? I mean, beside reducing the amount of water in the scene?

Richard Haseltine

I'm not sure what is happening, I was just expalining what the path length is measuring since that seemed unclear. Each passage through a shell will count as an interaction for path length (unlike 3delight, where its similar property counts only ray-traced intractions like reflection and refraction).

feldarzt

And thank you for that. It was unclear to me indeed.

feldarzt

A bit of continuation and a theory about what's happening with the Caustic Sampler.

It seems that, at some point, Iray does indeed overload if a scene has a lot of caustic stuff (water, other liquids, glass [especially non-flat], gems... basically, anything that is reflective and not completely opaque).

A few frames later, the fog and some of the water drops became unnecessary for the scene, so I removed them. After that, rendering with Caustic Sampler worked like a charm.

Long story short, keep your possible reflections as few as possible :)

@emu42