I'm experimenting with motion blur on smoke but it doesn't look like it should.

To get motion blur I
- Add an attribute Wrangle before the density volume with @v = 10*@N; so now the smoke flies out from a sphere. that means I have the vel attribute in the voxels.

I do get motion blur but its a very strange motion blur, it doesn't seem to have anything to do with how the smoke is moving. It seems as if its only thinks that the velocity is only pushing out from the center (I guess based on the normals).

But is Houidni not taking the wrong “velocities”? I mean what we really need to have are the velocities from how the smoke is moving inside the voxels and not how the original velocity field looks, right? Maybe I can output these velocities and use them to use instead?
In Fume FX the motion blur seems to be linked to how the fire and smoke moves which works very well.

Any ideas would be great!
/Andreas

It is taking the vel field and using that to add motion blur. I think you will find if you do a volume trail on your vel field you would have those massive velocities in the middle.
The error come into it because your vel field is a representation of the instantaneous velocity of the system, not how the smoke is moving over the shutter time.
Best bet is to clamp the magnitude of the vel filed.
eg:
in a volume wrangle to clamp to 10:

@vel=normalize(@vel)*clamp(length(@vel), 0, 10);

JordanWalsh
in a volume wrangle to clamp to 10:

@vel=normalize(@vel)*clamp(length(@vel), 0, 10);

Hi Jordan, thanks for the help.
Where would be the best place to put such a volume wrangle. Directly after the create or in the simulation?
/Andreasd

Put it after you import your fields from dops