Houdini 20.0 Nodes Geometry nodes

Volume Velocity from Curves geometry node

Generates a volume velocity field using curve tangents.

Since 16.5


Velocity Volume

Voxel Size

The voxel size to use.

Smooth Velocities

Smooth velocities after interpolating them from curves tangents.

Voxel Radius

The smoothing radius in voxels.

Blur Iterations

The number of times to perform smoothing.

Reference Volume

Reference Volume

Create the velocity volumes using this volume as a reference.

Activate Voxels by Reference Volume

Create velocity volume voxels in regions where the reference volume is active.

Match Reference Volume

Match the transform and voxel size of the reference volume.

Surface Geometry

Determine Voxel Size from Average Primitive Area

Set the voxel size to the square root of the average primitive area.

This is usually a good size for effects that require accurate volume data close to the surface.

Voxel Scale

The determined voxel size is scaled by this factor.

Activate Voxels by Surface

Create velocity volume voxels in a band around the second input’s surface geometry.

Exterior Band

The width of the volume band on the exterior of the surface.

Interior Band

The width of the volume band on the interior of the surface.

Fill Interior

Fill the interior of the surface with voxels.

Follow Surface

Force the created velocities to be tangential to the surface. This only works within the surface band, specified by Interior Band and Exterior Band, not in regions activated by other means.

Surface Lift

Direct velocities away from the surface. Setting this to 1.0 makes velocities point straight out of the surface.


It is possible to use negative values to direct velocities into the surface.

Curve Lookup

Radius Mode


Look up curve tangents within a constant radius.

Find Minimum Number of Curves

Automatically compute an appropriate radius that will include at least the specified number of curves.

Radius Volume

Sample radius values from a volume in the 3rd input.


The constant curve lookup radius.

Minimum Curves in Radius

The minimum number of curves to include.

Radius Volume

The volume to sample radius values from.

Radius Multiplier

A multiplier against the computed or sampled radius.

Curve Weights

Use Curve Weight Attribute

Multiply computed weights by a curve attribute.

Curve Weight Attribute

Multiply computed weights by this curve attribute.

See also

Geometry nodes