Velocity export issue

[jop]

Hi,

I'm really having hard time to export liquid mesh velocities for motion blur rendering.
I do it as described in the documentation.
Here are my several results:
- abc export + VRProxy: not as nice, small offset compared to PHX native
- abc export + max import with channel 2 VRay prop: bad, 1 frame offset
- xmesh export + max import with channel 2 VRay prop: about 1/2 frame offset

Overall the exported attempts are not as clean as the native motion blur rendering, with some black artefacts and vector issues (ie liquid laying on the ground have strong downward velocities).

The closest result I got is by rebuilding velocities from liquid particles in houdini, but it's hard to ged rid of black artefacts.
This experiment made me think that phoenix is taking the velocities from the particles instread of the grid for meshing, as the grid ones seems a bit messy when loaded in houdini.

I currently tried with phoenix fd 4.3 stable. Will do some more tests today with nightlies and post test scene if needed.

Thanks for your help.

[Svetlin.Nikolov]

Hey,

The mesh velocities come from the voxels, this is one thing to be certain about.

Sadly, 3ds Max's alembic export is one big hack at the moment and is not open for 3rd party developers. Everything points towards making our own alembic export that will be able to handle everything properly.

How do the black artifacts look though, can you show an image?

Cheers!

[jop]

Thanks for the quick reply.
Sure I'll show you some pics today.

[jop]

While XMesh is generally good at this it is even not able to make good job with phoenix

[Svetlin.Nikolov]

If you can give us something to work with, we can make this better...

[jop]

Here the scene + renders:
https://we.tl/t-pQPwUIn873

[georgi.zhekov]

Hey,

Thanks a lot for the files. We have reproduced the issue.

Will update the thread once we have something.

Cheers!

[jop]

Great, thanks!