Hi! Ultimately I'm trying to extract velocities from a mesh out of a vellum sim into a volume which I can then apply to advect some other stuff like particles. I can't get this basic setup to work though. Using volumevelocity SOP, just simply copying a v attribute onto a volume doesn't ever produce any readings on a volume slice - however other functions like curl noise behave as expected.

hi,

there a several ways to do this (wrangle ec.). in the hip i use a volumevop with a nearpoint vop to sample v from a geo. the hipfile provides a particle-upres workflow but you see how it works.

nic.

Thank you e_noni, this looks great and easy to setup.

Meanwhile, are SOPs such as volumevelocity or volumefromattribute just not appropriate for velocity transfer or am I doing something wrong in my setup?

I'm actually running in to this same issue with the volume velocity node and point velocities. curl noise and stuff like that visualizes fine but when i try to pump points with a @v attribute in to the 2nd input it doesn't seem to register no matter what i do. Has anybody gotten this to work?

same issue its not working insanely strange after all these years it is still not working

seems to work for me, it internally uses Volume From Attribute which means that it will sample the point velocity only for existing active voxels

if you want to create volume velocity from an arbitrary pointcloud without supplying the volume beforehand you can use Volume Rasterize Attribute SOP or VDB From Particles SOP

I had this issue in 19.5 when the input was a vdb vector volume: point velocity mode did not work. If it is converted to a native Houdini vector with 3 parts, it works. It seems the Volume from Attribute sop inside the volumevelocity HDA expects a native volume.
Haven't checked to see if this is changed in H20