VRay Velocity pass and liquid meshes

[japetus]

How does one get post motion blur with phoenix liquid meshes? I tried vray velocity pass which seems to render on some frames but not others, and then freaks out on other frames. I'm surprised it worked on as many frames as it did. I also tried rendering the phoenix grid texture velocity map as a separate pass which kind of worked, but am hoping to do some post blurring. I need to motion blur the collision object and the liquid. I am doing some post coloring which is much easier w/o MB turned on. Thanks as always for answering my silly questions!

[georgi.zhekov]

Hey,

Can you show us how the strange frames look like?

In order to get velocity pass, just make sure that you have the velocity channel enabled in the output rollout (before running the simulation) for the liquid and if have foam or splashes (turn it on for them as well).
Then just render and it should work for the liquid mesh. For the Foam and Splashes you will need to set the Particle shaders that render them to Geometry Mode.

Cheers,

[japetus]

Here's an example... the saturation has been turned up a bit to better show what's going on... velocity seems to render ok locally but on the farm is where it's freaking out and it's not consistently one machine or another and about half the time the velocity pass is just blank. As far as I can tell all the machines are up to date with the same version of Max, Vray, and Phoenix. My other passes are rendering fine, including Phoenix Grid Velocity.


I'm on Max 2020.1, phoenix 3.14.01 and vray 3.7.01

[georgi.zhekov]

Can you send over the scene to the support mail along with V-Ray logs from the problematic frames so we can check out what is going on?

Thanks,

[japetus]

Sent! Thanks!

[georgi.zhekov]

Thanks a lot for the scene. We managed to reproduce the issue and logged it as a bug in our system.
Looks like it happens when you render in Mesh,Cap Mesh or Ocean mesh mode and you have Render Cutter enabled.

As a workaround until we fix the issue you could use the Isosurface render mode.

Cheers,

[japetus]

Awesome, thanks!

[georgi.zhekov]

Hey,

Just wanted to let you know that this should be fixed in the latest Phoenix nightly build and it should render correctly.

Cheers,