Hi there,
I need to apply motionblur to a Volume!? And I can't figur out why it does not work.

enclosed the hip file,

Any advice would be nice,

thanks!

No one?…

No one?…

you need to either transform your volume on object level to get transformation mblur

or provide velocity data to your volume
such data is simply vector volume named “vel”
or rather 3 scalar volumes named “vel.x”, “vel.y”, and “vel.z”
“vel” volume contains velocity for each voxel and is used by mantra for motion blur

you will however need to compute it by yourself (for volume sims like smoke or pyro it is computed in simulation, but for your custom volume you need to build your own vel)

to build it you can use Volume SOP and then either transform “v” from some geometry to volume “vel” by Volume From Attrib SOP or compute in Volume VOP SOP, or use other way

thanks for your advice Tamte,

I need the transformation on sop level(this is just a simple test scene). there is already an velocity attribute…(trail sop) but no motionblur.

I just tried your advice with the Volume Sop but I dont know how to fetch the data in.

Enclosed the new hip file

Thanks Tamte!

here is one of the ways of doing it at SOP level

thanks Tamte!!!,

The IsoOffset SOP builds the volume, but what exactly does the volume sop?, does it just build a placeholder for additional attributes?

And is the velocity attribute for working with polygonal sops and for Volumes? I am a little confused.

It works great! thanks again!

Volume SOP in this case creates vector volume named “vel”
it actually consists of 3 scalar/float volume primitives named “vel.x”, “vel.y”, “vel.z”
you can see them by middle-click
and VolumeFromAttribute fills the values to these primitives in this case from “v” attribute of your moving geometry

and about “v” vs “vel”:

“v” and “vel” should both be recognized by mantra as velocity for volumes
for geometry there is only “v”

as I am used to work with volumes from DOPs I use “vel” because that's the name usually used in DOPs for volume velocity, I don't know the real reason
so sorry for confusion, you can use “v” as well

thanks tamte!

Hi! My question is similar to this topic.
How to disable volume motion blur at all? There are some geo objects and the smoke. Geometry is matte objects and they need a motion blur.
Smoke has no velocity, it blurred with Xform samples. And I don't know how to turn it off while maintaining a blur on other objects.