whats the deal with point vdbs?

[nuki]

stumbled upon point vdbs while doing some volume deformation stuff. the ability to convert voxels to points and back again would be very handy in that usecase. So, is it possible to

- convert a point vdb (eg. representing voxel centers) to a fog vdb and vice versa?
- access individual vdb points (eg. in a volumewrangle) for transformation/lookup/...  without unpacking?

this can all be done with a wrangle for point creation/deformation and volumerasterizeparticles. but since vdbpoints are apparently also stored in a grid they would inherently be a great intermediate "lattice" for volume deformations (and the inevitable interpolation required). But maybe I just misunderstand the usecase for vdb points (pc compression, rendering, ....?).

Edited December 10, 2020 by nuki

[Atom]

The use case that I am pursuing is using the Labs toolset to export the VDB points (not volume data) as a hbjson file. This is readable using the Labs Niagara plugin for Unreal. It's a way to export points from Houdini pyro, and use them in a particle system point source inside of Unreal.

Check out Simon's tutorial on the topic.
https://www.sidefx.com/tutorials/realtime-fx-with-niagara-ue4/
 

You can download the project files and review his HIP setups.

Edited December 11, 2020 by Atom

[nuki]

thanks for the explanation atom. Guess I misunderstood the application for point vdbs, although they seem very useful for exchanging pc data. no more baking sims to joints i guess!

Edited December 11, 2020 by nuki