Houdini 20.5 Nodes Geometry nodes

Volume Rasterize Attributes geometry node

Samples point attributes into VDBs.

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Since 17.0

The Volume Rasterize Attributes SOP takes a cloud of points as input and creates VDBs for its float or vector attributes. Internally, this node utilizes the Volume Rasterize Particles SOP and is thus subject to its nuances and limitations.

Inputs

Points to Rasterize

Geometry containing the rasterization targets.

Outputs

VDBs

VDBs generated from point attributes of the input.

Parameters

General

Group

A group of points in the input to rasterize.

Attributes

Pattern specifying which attributes to create corresponding VDBs for.

Note

Only float and vector attributes can be rasterized.

Source Attribute

When enabled, value of the specified string attribute will be used to isolate only the relevant points for each output volume. For example, when rasterizing the burn attribute, only points whose Source Attribute value is equal to burn will be considered.

Note

If the specified attribute does not exist on the incoming points, then the rasterization will proceed as if this option were disabled.

Note

Value of the Source Attribute can be a pattern. For example, if value of this attribute for a point is b*, then all rasterized volumes that start with the letter “b” will use the point.

Visible Volumes

Pattern specifying which volumes will be drawn as fog. If the name of a rasterized volume does not match this pattern, it will not be visible in the viewport.

Filter

Filter

The filter shape to use when splatting particles. The default Gaussian filter will produce smooth blobs and is useful for larger particles. When the particle size is smaller than the voxel size, a box filter will produce a similar result in less time.

Voxel Size

Voxel size for the created VDBs.

Particle Scale

The pscale attribute will be scaled by this value. If this attribute does not exist, 1 will be used as the reference.

Minimum Filter Size

If the particle’s radius is much smaller than a voxel, it can appear to pop from grid-location to grid-location as it moves. This adds an additional blur to particles to ensure they are this fraction of a voxel. A value of 1 ensures the main-support for each particle is at least a voxel, guaranteeing that any movement of the particle will correspond to a smooth change in voxel values, at the cost of less sharp boundaries.

Velocity Blur

Velocity Blur

Enables rasterization of velocity blur. Velocity blurred particles are rasterized by creating multiple point samples along the velocity path and distributing the coverage of the original point among these samples.

Shutter

The shutter time to use for velocity blur rasterization.

Shutter Offset

The shutter offset to use for velocity blur rasterization.

Blur Samples

The number of motion blur samples to use for velocity blur rasterization. Larger numbers of samples will produce smoother and more accurate results, but will take more time to compute.

Coverage

Coverage Attribute

Name of the point attribute that stores the coverage (or influence) of each particle. If the coverage attribute does not exist, each particle is assumed to have a coverage of 1.

Coverage Scale

The coverage attribute will be scaled by this value.

Normalize by Clamped Coverage

Enabling this option multiplies the sampled volume by coverage, yielding a smooth transition between areas covered by the particles.

Note

This option changes the default stamping method from Weighted Average to Covered Average; Attribute Rules can be used to override this default behavior.

Attribute Rules

Rules that specify the stamping method on a per-volume basis.

Note

If multiple rules apply to a volume, the first one is used.

Note

The Coverage Attribute is unconditionally stamped using the Accumulated method.

Attributes

This pattern identifies volumes to which the rule applies.

Method

Stamping method to use when generating the volumes to which this rule applies.

Weighted Average

Voxel value is weighted average of attribute value from the overlapping particles; weight depends on the coverage attribute, as well as distance of the particle from the sample location.

Covered Average

Same as Weighted Average, but areas outside of particle influence are attenuated, yielding smooth falloff.

Accumulated

Contributions from all particles are simply summed up.

Stochastic

Voxel value is deduced from a single (pseudorandomly selected) overlapping particle.

See also

Geometry nodes