Houdini 20.0 Nodes Geometry nodes

VDB Smooth SDF geometry node

Smooths out SDF values in a VDB volume primitive.

Since 12.5

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

This node applies a simulated flow operation, moving the surface of the signed distance field according to some local property.

For example, if you move along the normal by an amount dependent on the curvature, you will flatten out dimples and hills and leave flat areas unchanged.

Unlike the VDB Smooth SOP, this node ensure the SDF remains valid.

Parameters

Group

The VDB primitives to be smoothed. See specifying volumes for more information.

Alpha Mask

If enabled, it will use the second input’s VDB for alpha masking. Assumes voxel values are between 0 to 1 inclusive. See specifying volumes for more information.

Operation

What sort of smoothing process to apply to the VDB.

Mean Value

Find the mean (total/count) of the surrounding values. This is equivalent to a box blur of the same radius.

Median Value

Find the median (middle value) of the surrounding values. This is useful for de-spiking noisy data as extreme values will not contribute to the final result.

Mean Curvature Flow

Finds the average curvature at each location. Moves the surface along the local surface normal to flatten out bumps.

Laplacian Flow

Finds the local “Laplacian” to control how much to move along the normal.

Filter Voxel Radius

The number of voxels to run the smooth operation over. This is measured in voxels, not distance. This distance defines a cube, so increasing the “radius” will exponentially increase the work.

Iterations

Number of times to repeat the smoothing operation.

Invert Alpha Mask

Inverts the alpha mask so that values from 0-1 maps to 1-0.

Min Mask Cutoff

Alpha mask values below this are mapped to 0.

Max Mask Cutoff

Alpha mask values above this are mapped to 1.

Trim

Set voxels that lie outside the narrow band to the background value.

Optionally set interior, exterior, or all voxels that lie outside the narrow band to the background value.

Trimming reduces memory usage, but it also reduces dense SDFs to narrow-band level sets.

See also

Geometry nodes