So I have been doing some work with custom velocity volumes and have been puzzling over a few things. For instance, the volume vop allows me to bind and iterate over vector volumes, but I can't seem to figure out how to tell which volume it is processing. Is there a way to tell which primitive the current voxel belongs to?

Another thing I have had trouble with is finding the proper way to combine vector vdbs. No matter what I do it complains that one of the inputs has move volumes than the other.

Finally I am a little confused about how to properly create and initialize scalar and vector vdbs. Any tips?

Thanks!

90ender
For instance, the volume vop allows me to bind and iterate over vector volumes, but I can't seem to figure out how to tell which volume it is processing. Is there a way to tell which primitive the current voxel belongs to?

Volumes are bound by name in the Volume VOP. See the help for the Volume Bindings parameter tab. So you know which primitive because it's the primitive that you named.

Another thing I have had trouble with is finding the proper way to combine vector vdbs. No matter what I do it complains that one of the inputs has move volumes than the other.

Finally I am a little confused about how to properly create and initialize scalar and vector vdbs. Any tips?

Which nodes are you using? To create a vector VDB out of scalar VDBs, use VDB Vector Merge. Once you have matching primitives, VDB Combine should would. Make sure your groups are specified appropriately. To initialize VDBs, try VDB Activate.

the volume vop is by default binding volume by name, or explicitly if defined in Volume Bindings tab, you can as well access other input volumes or volumes from file by name/index using Volume Sample (from File) VOP, Volume Gradient (from File) SOP

do you have any example of VDB Combine complaining when you have just one vector volume plugged to each input as you are describing?

for creating VDB volumes you can use VDB SOP, or VDB from Particles, VDB from Polygons (both can create volumes from individual attributes as well)
Convert VDB from houdini volumes, or VDB SOP with Volume Rasterize Points/Particles, …

EDIT: too late to the party