Houdini 20.0 Nodes Geometry nodes

VDB Reshape SDF geometry node

Reshapes signed distance fields in VDB volume primitives.

Since 12.5

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

This node changes the shape of an SDF field by moving the SDF surface in or out along its normals. Unlike just adding an offset to a signed distance field, this node properly updates the “active” voxels to account for the transformation.

Parameters

Group

The name of VDB primitive(s) in the input to be reshaped. 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 reshaping process to apply to the SDF.

Dilate

Expands the surface outwards along its normal.

Erode

Shrinks the surface inwards along its normal.

Open

First shrink the surface inwards, then expand it outwards by the same amount. This causes isolated hills and islands to be erased.

Close

First expand the surface outwards, then shrink it inwards by the same amount. This causes holes and valleys to be filled.

Use World Space for Offset

Sets whether the Offset amount is specified in Houdini units. When this option is off, the amount is interpreted as voxels.

Offset

Amount to move the surface in or out. This amount is assumed to be in voxels if Use World Space for Offset is off.

Renorm Accuracy

The method for smoothing the SDF after each iteration. Later options in the list are slower but more accurate.

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