MotionBlur with ThinkingParticles

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

Hi,

we have some strange problems when rendering ThinkingParticles with MotionBlur..

I made some example images:

First, this is the animation how it looks like in the Viewport:
http://www.koshigaya.de/misc/vray/Playblast.mov

This is a frame rendered with VRay MotionBlur:

This is the frame rendered with Scanline MotionBlur (multi frame)

This is the frame rendered with VRay MotionBlur and 20 Geometry Samples:

(I made a levels-correction - as you can see there are a lot of artifacts..)

This is the sequence rendered with VRay MotionBlur:
http://www.koshigaya.de/misc/vray/Rendering.mov

And this is the MaxFile (Max 2008, 64bit)
http://www.koshigaya.de/misc/vray/thinking.max

Do you have any idea how to solve the problem?

Best regards,
Aya

2

Looks like the vertex/polygon order changes within the motion blur interval which is generally caused by changing geometry (particles born / dying).

3

Yes, that’s what I think too… but how can this be solved?
I mean, if I raise the GeometrySamples it looks correct, but has artifacts..

4

Its up to Thinking Particles to handle it correctly. Basicly what you want is that the mesh doesn’t change inside your motion blur interval. If your interval is 0,9 frames. You want your mesh to stay same and just deform from Frame 0,05 to 0,95 (or so depending on motion blur center).

If Thinking Particles doesn’t have any special support for this then it will never work and you have to do 2D motion blur instead.

5

2D MotionBlur would be okay too, but there’s the problem.. the MotionBlur only works for the Beauty-pass, not for the renderElements of Vray :confused:

6

I meant rendering out velocity channel and using your composition software to render the motion blur

7

just asked our thinking particles guy and he said try going to the master dynamic and adjust viewport rendering sub sampling to half frames or samples per second
that should give you a different result
hope it helps

8

You can do this by making sure that the number of particles does not change within the motion blur interval. For example, if the number of particles changes only on a frame boundary, make sure the motion blur interval is only within a single frame (f.e. center 0.5, duration 0.5).

Best regards,
Vlado

9

So to revive this old thread; this is now solved for newer builds of V-Ray in a similar way as for Particle Flow.

Best regards,
Vlado