Render stuck at "Building dynamic mesh trees"

[santiago_gutirrezdepierespedraza]

I recently built a workstation with an RTX 4090 and started working with V-Ray GPU and Vantage. Unfortunately, the experience has been pretty frustrating. I’m running into a lot of strange bugs, crashes, and long parsing times. This time, my render get stuck at "Building dynamic mesh trees". It seems to be in an infinite loop, switching between "Building dynamic mesh trees," "Rendering image," and then back to "Building dynamic mesh trees." This happens very frequently.

Video:
https://www.mediafire.com/file/yqkfjreei5k89jl/Building_dynamic_mesh_trees.mp4/file

Windows 11 Home 23H2
AsRock B550 PG Velocita
AMD Ryzen 9 5950X 16-Core Processor 3.40 Ghz
Corsair Vengeance LPX DDR4 64 GB (2x32GB) 3200 Mhz
Gigabyte RTX 4090 GAMING OC 24G
Seasonic Focus V3 GX-1000, 1000W 80+ Gold

[santiago_gutirrezdepierespedraza]

Can anyone help me with this problem?

[hermit.crab]

Excuse the delay. Mind if you reupload the video?

[santiago_gutirrezdepierespedraza]

Excuse the delay. Mind if you reupload the video?

Hi Aleksandar!

Don't worry. I reuploaded the video.

This problem occurs very frequently, even in simple scenes like this one. I'd really like to get to the bottom of it and start considering V-Ray GPU for production. Any help would be greatly appreciated.

[glorybound]

Have you tried this?

• V-Ray tab, Use the CUDA engine
• V-Ray tab, Set Sampler to Progressive
• V-Ray tab, Frame Buffer section. Set Post Effects rate to 0
• Performance tab, Textures mode should be set to Full-Size, and Check Use System Memory for Textures option. No need for Compressed Textures with new V-Ray builds
• Performance tab, Uncheck the C++/CPU device
• Try to use the least amount of render elements. This affects performance considerably

[hermit.crab]

Hard to say what's happening without the scene. Send it so we can troubleshoot.

[santiago_gutirrezdepierespedraza]

Hard to say what's happening without the scene. Send it so we can troubleshoot.

Sent. Feel free to request more information if you need it. I'm really interested in seeing this solved.

Have you tried this?

• V-Ray tab, Use the CUDA engine
• V-Ray tab, Set Sampler to Progressive
• V-Ray tab, Frame Buffer section. Set Post Effects rate to 0
• Performance tab, Textures mode should be set to Full-Size, and Check Use System Memory for Textures option. No need for Compressed Textures with new V-Ray builds
• Performance tab, Uncheck the C++/CPU device
• Try to use the least amount of render elements. This affects performance considerably

Hi Bobby! Thanks for your suggestions! I’ll try some of them out in the meantime. My main goal, though, is to figure out the root cause of the issue—whether it’s hardware-related, a V-Ray bug, or something else. Any additional insights you might have on the cause would be very helpful.

[Joelaff]

No Alembics loaded with VRayProxy, right? If you Check Use Alembic Offset in these cases it will do what you described. (Uncheck it after checking it once to get the value and it works fine.)

[santiago_gutirrezdepierespedraza]

No Alembics loaded with VRayProxy, right? If you Check Use Alembic Offset in these cases it will do what you described. (Uncheck it after checking it once to get the value and it works fine.)

Could you elaborate please? I'm trying to understand what causes this problem.

[Joelaff]

Could you elaborate please? I'm trying to understand what causes this problem.

Not sure this applies to you, but if you have a VRayProxy object that is loading an Alembic, and you have the checkbox set to use the Alembic offset (for the start frame) it will do something like what you described. Just pointing out a specific case that is in the bug database already. Sadly, Chaos doesn't make the bug database public.

[santiago_gutirrezdepierespedraza]

Hard to say what's happening without the scene. Send it so we can troubleshoot.

Any update on this?

[hermit.crab]

Any update on this?

Probably a colleague of mine is troubleshooting it. What's your ticket number?

[santiago_gutirrezdepierespedraza]

Probably a colleague of mine is troubleshooting it. What's your ticket number?

Sure. Ticket number is 280389

[angel_kotsev]

The issue appears to be quite specific, where the IPR enters an endless loop on the first run after opening the scene but works as expected once any changes are made to the render settings.
I've reported the matter to our developers for further investigation in our internal system (VMAX-13140).

In the meantime, please continue using the workaround: reset the render settings by switching the render engine to Arnold (or another option), then switch back to V-Ray GPU, and then attempt to render with the IPR.

[santiago_gutirrezdepierespedraza]

Thank you for the update. Unfortunately, the suggested workaround only resolves the issue for the current session. Once I close and reopen 3ds Max, the problem reappears. Hope the devs can figure it out.