I have a houdini isosurface which I converted into a vdb levelset surface.

When adding some vdb operations, like “VDB renormalizesdf” I get an error message:
VDB primitive ‘surface’ has a narrow band width that is less than 3 voxel units.

When combining this level set with another later on, I can see some artifacts, so I think it may be from this warning.

So, how can I add more voxel units to my narrow band width?

Sample file attached.

To expand the narrow band of an SDF VDB, convert it to polygons and then back again into a VDB with the new voxel radius.

In the open source OpenVDB houdini SOPs, there's a “Rebuild Level Set” (or something like that) which does exactly this in one node.

Thanks, I'll try it.

workaround as edward mentioned. granted, the open source rebuild level set sop is super handy; perhaps you need to perform a really wide filtering operation and your narrow-band is too narrow; or maybe you did some destructive operation in a volume vop and need to re-establish a “proper” level set as per input to a CSG operation; etc…

-jeff

What I realized the other day is that you can just do what I said in a single node by just appending a “VDB From Polygons”. When it encounters non-polygon geometry (eg. VDBs), it will first convert to polygons, and then it will convert it into a VDB. Voila! Level set rebuild.

Hi, sorry for reopening that thread.
You could also drop a "vdbactivate" node, and increase the "Voxels to Expand" parameter. This works with SDF and fog volumes.