Particle Fluid Mask geometry node

Generates a Volume mask from a particle fluid simulation.

On this page	Parameters Mask Conditions Regions Mapping Spectrum Amplitude Inputs Outputs
Since	16.0

Connect particles and/or velocity fields from a particle fluid simulation to the Particles and Volumes input of this node to generate a volumetric mask according to several different criteria.

Additionally one or more Ocean Spectrum layers can be connected to the third input of this node, and the generated mask can be composited into the existing spectra masks, with optional frequency filtering applied to the spectra.

Parameters ¶

Mask ¶

Particle Separation

The distance between two particles in the fluid simulation. This parameter should generally reference the same parameter on the FLIP Object of the input simulation.

Resolution Scale

Scale the output mask volume relative to the input particles and/or velocity fields. This parameter can often be set below 1, because a mask is often blurred using the Filter parameter, and very high resolution masks are usually not worth the processing expense.

Use Input Volumes Only

Ignore particle input and create the mask only from an input velocity volume. In general this operation is faster than using particles and is very useful for previewing mask values; however, it will be less accurate and might miss areas where only a few particles exist and the velocity field is not defined in the source FLIP simulation.

Spectrum Mask Type

Controls if the mask should be combined with any ocean spectra plugged into the second input, and if so, whether it should suppress or contribute to the ocean waves.

Conditions ¶

Velocity Range

Generate a mask where surface areas with velocity below the minimum speed get no masking, while areas above the maximum speed get full masking.

Vorticity Range

Generate a mask where surface areas with vorticity below the minimum speed get no masking, while areas above the maximum vorticity get full masking.

Collision Offset

Generate a mask within the specified world-space offset of any collision objects or volumes connected to the second input.

Height Range

Generate a mask where areas below the minimum height get no masking, while areas above the maximum height get full masking. The height is measured relative to the specified Plane.

Conditions Combine

The operation used to combine multiple filter masks from the Conditions tab.

Regions ¶

Use Bounding Box

Fade out the mask as it reaches the edge of the specified bounding box, according to the Falloff Shape and Falloff Distance.

Size

The size of the bounding box.

Center

The center of the bounding box.

Falloff Shape

The shape in which the mask should falloff as it approaches the edges of the bounding box. If creating a mask for a fluid mesh created with the Particle Fluid Surface SOP with Flatten Geometry enabled, this value should match the flattening Shape.

Falloff Distance

The distance at which the mask should falloff as it approaches the edges of the bounding box. If creating a mask for a fluid mesh created with the Particle Fluid Surface SOP with Flatten Geometry enabled, this value should match the flattening Distance.

Plane

The plane in which height is measured and falloff occurs.

Invert Bounding Box

Invert the mask created by the specified bounding box.

Regions Combine

The operation used to combine masks from the Regions tab with those from the Conditions.

Mapping ¶

Filter

The type of smoothing to apply to the mask.

Use World Space Radius Units

Specify the Filter Radius in world space rather than voxel units.

Voxel Radius

The size of the filter radius in voxel units.

Filter Radius

The size of the filter radius in world units.

Iterations

The number of smoothing iterations to perform.

Invert Mask

Invert the output mask.

Remap Mask

Remap the output mask according to the Remap Ramp.

Remap Ramp

The ramp for remapping the mask output.

Spectrum ¶

Amplitude ¶

Filter Above Resolution

Dampen any waves that would exist in an ocean spectrum higher than this resolution. For example if set to 8, this spectrum will have no higher frequencies than a spectrum of resolution 8. This parameter can be useful along with Filter Below Resolution when layering spectra and applying masks and noise to only the highest frequencies.

Filter Below Resolution

Dampen any waves that would exist only in an ocean spectrum lower than this resolution. For example if set to 8, this spectrum will contain only frequencies higher than a spectrum of resolution 8. This parameter can be useful along with Filter Above Resolution when layering spectra and applying masks and noise to only the highest frequencies.

Filter Above Wavelength

Dampen any waves that have a longer wavelength than this value.

Filter Below Wavelength

Dampen any waves that have a shorter wavelength than this value.

Remove Non-Spectral Waves

Remove any non-spectral instanced waves, usually those created by the Ocean Waves SOP. Since these waves are typically low-frequency, this option is useful in combination with Filter Below Resolution to remove all low frequencies from the input spectra.

Inputs ¶

Particles and Volumes

Particle geometry and/or velocity field, usually from a FLIP simulation.

Collision Objects and Volumes

Geometry and SDF volumes to subtract from the fluid surface.

Ocean Spectrum

One or more ocean spectrum layers from Ocean Spectrum SOP(s).

Outputs ¶

Mask

The mask volume.