I am currently having an issue when exporting volumes with solaris
It is partially solved but I'm not that happy with my solution right now.The situation is the following:
I want to export a bunch of volumes with different transforms which are grouped together like this:
volume0
- density
- vel
- ...
volume1
- density
- vel
and so on. I will also mention issues with vray that brought me to the different solutions to paint the full picture :S
At the beginning i just set one usdvolumesavepath for all of them so they all get written to the same vdb file in the end.
But I ran into an issue with this because it looks like vray picked the wrong transforms for every volume group other than the first volume0
(i believe the later density volumes picked the volume0 density transforms and so on instead) So if i wanted to store the transform inside the vdb i needed to have matching transforms for all primitives.
One idea to "solve" this was to put all the volumes to the origin by inverting the transforms in sops and adding the transform back to the volume0, volume1, .. prims in solaris. But that caused major issues in motion blur since if the volume was resizing from frame to frame the transforms would change rapidly. And those transforms are interpolated between frames so the volume wouldnt change but the transforms would until it reaches the next frame and it would snap back to the correct position causing jittering.
So my current solution is to have a separate usdvolumesavepath for each volume group volume0, volume1 and so on which share the same transforms inside the vdb. which seems to work. the issue is just that the transforms inside arent used for motion blur at all so while it does get rid of the jittering if artists wanted to animate the volumes themselves they would have to add that motion to the velocity field in order to have correct motion blur. (i guess one way would be to add the animation itself on the volume groups transforms in solaris? but i dont want to go that route since it is easier for the artists to do it in sops : S)
My question is can I somehow get the transforms on the volume groups to work? Since that seems to be the cleanest solution in my mind right now : S. There is no way to have stepping interpolation for transforms in usd right (i guess that would mess with the mb as well)?
If any of the previously written things are false please tell me - also im not sure if i am correct in posting this issue here since it is regarding vray and houdini
Anyways any input is appreciated and thanks in advance!