Houdini 20.0 Nodes Geometry nodes

VDB Resample geometry node

Re-samples a VDB volume primitive into a new orientation and/or voxel size.

Since 12.5

See volumes for an explanation of standard volumes and OpenVDB volumes.

Note

This node does not filter the results. If you change the resolution you may get aliasing artifacts.

Parameters

Group

The name(s) of the VDB volume primitives in the input to be re-sampled. See specifying volumes.

Reference VDB

If the second input is connected, you can enter the name of a VDB primitive in the second input to copy the orientation and voxel size from it.

See specifying volumes.

Interpolation Order

How to interpolate positions.

Nearest neighbor

Choose the value from the nearest voxel. This is fast but can cause aliasing artifacts.

Tri-linear

Matches what Volume Mix and volumesample do.

Tri-quadratic

Smoother than tri-linear, but slower.

Define Transform

How to generate the new VDB’s transform.

Explicitly

Define an explicit transform to resample with. Note that this is specified in index space, not SOP space, so the translation amounts will scale with voxel size.

To Match Reference VDB

Use the transform and voxel size from a VDB in this node’s second input. The result is a copy of the first input, aligned to the second input.

Using Voxel Size Only

Set a new voxel size, increasing or decreasing the resolution. This can be applied to the transform of the input VDB or as a new axis-aligned linear transform.

Using Voxel Scale Only

Scale the voxel size, increasing or decreasing the resolution. This can be applied to the transform of the input VDB or as a new axis-aligned linear transform.

Transform Order

The order of operations for the new transform.

Rotate Order

The order of rotations for the new transform.

Translate Voxels

The shift, in voxels, of the new transform.

Rotate

The rotation for the new transform.

Scale

The scale for the new transform.

Pivot

The pivot point for the new transform.

Voxel Size

The size of voxels in the new VDB. Larger voxels correspond to lower resolution.

Note

This parameter is only visible when Define transform is Using voxel size only.

Voxel Scale

The amount by which to scale the voxel size in the new VDB. Larger voxels correspond to lower resolution.

Note

This parameter is only visible when Define transform is Using voxel scale only.

Force Axis Aligned

Apply the input VDB voxel size or scale size to an axis-aligned linear transform. And axis-aligned linear transform cannot have taper. Disable this toggle and the transform of the input VDB is used.

Transform Vectors

When Define transform is “Explicitly”, apply the transform to the voxel values of vector-valued VDBs according to its Vector Type.

Rebuild SDF

Transforming (especially scaling) a SDF might invalidate signed distances, necessitating its reconstruction. This option affects only SDF volumes, and it should almost always be enabled for those cases.

Prune Tolerance

Remove voxels within this distance of the VDB primitive’s “background” (empty) value. This is necessary since the resampling can create active but “empty” voxels.

In general, you should leave this option on. Expert users may want to turn this off based on very specific situations. For example, if you know that pruning empty voxels is a waste of time since a later operation will reactivate many of them.

See also

Geometry nodes