Tyflow motionblur support with lots of particles (Even not working in Vray 7.0)

[eXeCuze]

Hi,

I am currently trying out the latest Vray 7 build and I have to say that I am pretty disappointed that motionblur still doesn't seem to work properly with Vray gpu.
I try to render lots of particles which is all going fine until the point that I enable motionblur on my camera. It does work fine in Vray CPU, but it would of course be great if this would work properly in Vray GPU as well.

Is there any workaround or am i missing something?

Please let me know.

Thanks in advance!

[nicolas_fuminier]

Hello,

Did you use a Tycache for your particles (with velocity channel enable ?). That might fix the issue.
It work in production render here (Vray 6.20) but it can fail in IPR (first frame might work and the second you change anything in the IPR the motion blur fail)

I don't have your full setup / issue here, but it's a common question.

Best,
Nicolas

[eXeCuze]

Hi Nicolas,

Sorry I wasn't clear in my post.
Motionblur does work on tycaches with Vray gpu, but it is extremely slow when trying to render lots of particles with motionblur. So slow that it isn't usable at all.

[nicolas_fuminier]

Ho, sorry, I first thought it didn't work at all.

You might experiencing a VRAM issue here, do you have enought VRAM on your Graphic card to handle the render ?
If you are rendering with RTX, you might try CUDA rendering (slower but more stable and less VRAM consuming).
if you are rendering with light cache, you might want to try with brute force (same, slower but more stable and less VRAM consuming)
I totally understand that each one of my advice looklike a more slower render, but first you have to ruled out stability and VRAM issue.

You might also monitoring your VRAM during calculation with your windows task manager or by following those advice on the technical setup (check also your driver) :
https://forums.chaos.com/forum/v-ray...age-on-windows
https://forums.chaos.com/forum/v-ray...-gpu-rendering
https://forums.chaos.com/forum/v-ray...gpu-on-windows

Nicolas

[eXeCuze]

I have 24GB of Vram which should be more then enough. It just is a tyflow compatibility issue. This really only occurs when rendering with Vray GPU (both RTX and CUDA). Other render engines like Redshift or Vray CPU render those caches fine.
And I even was able to export the cache to an alembic and render them with a Vrayproxy without any issues. This for now is a workaround which I am using, but it would be great to be able to render lots of tyflow instances with motionblur without any issues on Vray GPU as well.

[nicolas_fuminier]

Is your Tyflow up to date ?
Is your cache store only data points and call geo after the Tycache (by the Tycache) or is your Tycache store also the geo ? Maybe the instance geo is not working properly and the render engine struggle to store all the geo ?
Or maybe you reach the limit of the render engine.