particle shader motion blur

[chris_img]

Hi, i'm in the middle of a project and have discovered a look the client likes using particle shaders to create trails behind an object. Problem is, its footage from a phantom camera fps=@800, and i've been using a retimer in nuke to slow the particles down to match, all good so far. Now i've realised i can't retime in post, so i have to match the animation in max @ the slow fps. I'm losing the cool looking curves created from the motion blur of the fast moving particles and its really annoying. I tried upping the motion blur mult. spinner to 2.0 but i'm getting the linear staright lines you would expect as the particles trajectory is calculated over 1 frame.

So no more sexy looking curved trails.

Can anyone think of a solution to this?

I've tried setting the motion blur drop down to from renderer and increased all the camera settings to a really long shutter but it doesn't seem to do anything.

[chris_img]

Ok, i think i've found a solution;

by rendering out a velocity pass and really cranking the settings up in the vector blur!

[chris_img]

Nope, can't seem to get the paricles to show up in the velocity pass.

Is there a switch or tick box i need to turned on to get the particles in the velocity pass?

[Gosho.Genchev]

Do you have the velocity channel export enabled under the Output roll-out. It should be enabled by default but please check anyway. Also, if you're using the particle shader, enable the "Render as Geometry (V-Ray) option".

Cheers!

[chris_img]

Do you have the velocity channel export enabled under the Output roll-out. It should be enabled by default but please check anyway. Also, if you're using the particle shader, enable the "Render as Geometry (V-Ray) option".

Cheers!

It was this i was missing, just seen it in the help docs, thanks Gosho.