There's a .vdb file format (which you'd use to export to other apps), but you don't need to write out a .vdb file to get the space savings, just having a VDB primitive in Houdini is enough. A Houdini volume primitive can be converted to a VDB primitive at any time, just put down a convertvdb node, set its mode to VDB.What is the difference between Native Houdini vector volumes and VDB volumes?
Something to note is how native Houdini vector volumes and vdb vector volumes differ. Internally Houdini doesn't really have a vector volume format, but it creates 3 scalar volumes, and knows to treat them as a single entity. A standard smoke setup that uses density and vel will have 4 volume primitives; density, vel.x, vel.y, vel.z.What is the difference betweenvdvdb and standard Houdini volumes?
VDB allows true vectors at each voxel, while standard Houdini volumes use three scalar volumes to do the same thing. Precision The numerical precision (32-bit or 64-bit) to use when using a Storage Typeis "Float" or "Vector float".How do I find the volume type of a Houdini node?
Houdini supports 2 volume types, its own volume format, and VDB. These are treated as primitives like polys or nurbs, if you middle click and hold on a node, you'll see it say '1 VDB' or '1 Volume' or similar.