Vray motion blur with over a million particles

V-Ray V-Ray for 3ds Max General
1

Hello,

I have problem rendering Phoenix FDs created particles. My splashes count is 1.3 million, and if I render them without motion blur, its very fast.
But after switching camera motion blur on, I got unbelievable long render times.
I havent find any good setup with Adaptive subdivision and Adaptive DMC.

First I think it was about refraction and reflection, but after switching off all shadows refractions and about everything in Phoenix particle setup, nothing gives me enough speed for the rendering.

So could anyone more experienced Vray user give me some hints to get my motion blur rendering more efficient?

2

Maybe im just too encouraged to get motion blur with such over kill amount of particles.

Still if someone can share some good universal settings for motion blur I would be happy.

3

Depends on the material that you’ve got applied to the particles, adaptive dmc should definitely be better though.

4

Thnx joconnel, I´m using default Phoenix particle material which seems to be just a basic white material and option to switch refraction on it. Adaptive DMC sounds nice, but can it be tuned with some other reasonable values? Like how is min and max subdivisions in dmc sampler making any difference and should I increase or decrease motion blur´s subdivs to speed up rendering?

5

This would be more of a Phoenix FD problem, rather than a V-Ray one; you might want to post in the appropriate forum section.

Best regards,
Vlado

6

Ok, vlado. I made some test and basically it seems that under 100 000 particles gives good render times. Still if some tune up could be done with DMC I would like to hear.

7

how much slower is it?
just for the test, switch to fixed image sampler, no vray mb, and force on the foam mb. if the rendering is still too slow (2 or more times slower than without mb), this refers to tree problem, may be too big velocities.
if the rendering is fast, this means the image sampler settings or the vray mb settings.

8

Thanks Ivo!
Tree problem it might be, cause with fixed image sampler without motion blur it renders over 400 000 particles in 24 second, and with forced motion blur it gives over 30 minutes render time.

And the state of my liquid simulation at that time is a situation with almost an explosion of water.
So maybe the answer is to tweak my simulation rather than DMC sampler like Vlado said.

9

ok, send me the scene, let see what we can do.

10

This time I think I spare your time Ivo and won´t send this particular scene, cause I think I have just too small grid box and so big object (train) falling to the sea. Also in my test R&D scene my train has too much velocity and this combination creates an explosion on my grid box.

In future if I still have problems and cant tweak my scene on my own, I might contact you and send the file. Thanks again!