Maya-Vray Crashes Rendering Subdivisions W/ GPU

[jtrudeau]

Hi All,

I was wondering if someone has some ideas of what might be causing Vray to crash when rendering objects that have subdivisions checked with the GPU. I've tried deleting my preferences and reverted to the Vray defaults in the rendering settings with no luck. I get "Fatal error rendering scene." in my script editor when I real time render and it just crashes during normal renders.

I'm using VRay 1.1 for Maya 2019.2 with 2 TitanX's as my GPU. Windows 10 professional.

Thanks for any ideas or help you can provide.

[hermit.crab]

You may be running out of Vram. How much Vram does your GPUs have? Also, you may try reducing the Max. subdivs or increasing the 'Edge length' in the render settings (Settings>Default displacement and subdivision). If that doesn't help, it would be best to send the scene to support@chaosgroup.com for investigation.

[jtrudeau]

Hi Aleksandar,

I have 12 gigs of Vram per card (2 total) so I didn't think it was the issue when I was researching why this is happening. I'm definitely no expert so you would know better. I'll try your suggestion of reducing the Max Subdivs and increasing the edge length in Vray. To make sure I'm enabling subdivisions properly, could you tell me what is the best way to achieve Subdivs for Vray? I've tried 2 ways, which are listed below.

1. I go into each of the smoothed shape's attributes and enable VRay subdivisions.

2. I select all the shapes that are smoothed and create a single VrayDisplacement to the selection under the create menu. I then enable Sudivisions and Displacement in the render settings.

I just want to make sure I'm not inadvertently causing Vray to crash in addition to any of the issues you listed above.

Thanks very much for helping me with this.

-JRT

[hermit.crab]

Both methods are correct in terms of subdividing geometry (you may also use Maya's OpenSubdiv method as well) - so no need to worry about that. In addition to the scene, please attach the "vray4maya_log.txt" and "MayaCrashLog" dump file (both in the windows %temp% folder ) in your e-mail and mention this thread as well.
Also, a side note that may of use - the GPUs' Vram is not shared between cards unless they are linked physically linked.

[jtrudeau]

I tried rendering the scene twice - once with smooth mesh preview applied to the smoothed objects and another time with the subdivisions "baked" into the objects. Both times the rendering crashed before getting started. I've sent you the log files as well as a scene with couple elements that crashed VRay (I can't send the whole scene for work reasons).

To you comment about the VRam shared between cards. I was under the impression the RAM required for rendering a scene is shared between cards as long as the are both plugged into the same motherboard and that an SLI connection will only screw things up for rendering. Am I way off the mark in that assumption?

Thanks, sending the email now.

[hermit.crab]

Thanks for the provided scene and information. The crash seems to produced by the excess amount of mapping channels in some of your objects. Currently, V-Ray GPU supports map channels from 0 to 15 (as stated in the technical documentation), so clearing some of your UV sets should eliminate the issue. Try this and report back with feedback.

Regarding the Vram sharing - for the memory to be shared, the GPUs must be linked via NVlink (the cards also need to be NVlink supported naturally).

[jtrudeau]

Aleksandar, you just saved my ass. I looked for every reason VRay might be crashing, expect for UV maps. I brought in a piece from a kitbash set then combined and separated it with several objects when I was designing for work. It must have added all its UV maps to the objects without me realizing it. Thank you so much, there is no way I would have found that without your help, Vray works great now.

Thanks again, if I could send you a bottle of wine over there I would.

-JRT