Houdini 20.5 Nodes Geometry nodes

Guide Mask geometry node

Creates masking attributes for other grooming operations.

Since 16.5

This operator creates and manipulates attributes that can be used to drive other grooming operations.

Parameters

General

Group

Group Type

The type of input group.

Group

A group to use for masking. Any operations will only be applied to the primitives or points within this group.

Set Ungrouped to Zero

Sets the mask value of any primitives or points not specified within the Group parameter to zero.

Input Mask

Input Mask

The initial value of the mask. Other masking operations are multiplied with this value.

This parameter can be overridden using an attribute or texture. To do this, select an option from the drop-down menu next to the parameter.

Output

Visualize Mask

Visualize mask values in the viewport.

Output Type

The type of attribute to create.

Primitive

Create a primitive attribute.

Point

Create a point attribute.

Output Attribute

The name of the output mask attribute.

Create Group of Affected Primitives

Create a group of all primitives that have non-zero mask values.

When Output Type is Point, any primitives that have any point with a non-zero value are added to this group.

Group

The name of the group of affected primitives.

Output Integer Attribute

Create an integer attribute with a specific value for any affected primitives.

Integer Attribute

The name of the integer attribute.

Value

The value to set the integer attribute to.

Mask Threshold

The integer attribute is only set on primitives that have at least this mask value.

Additional Masks

Noise Mask

Use Noise Mask

Masks using a noise function. When a 'rest' attribute it exists it is used as the noise space.

Amount

The amount of noise to apply.

This parameter can be overridden using an attribute or texture. To do this, select an option from the drop-down menu next to the parameter.

Frequency

The frequency of the noise.

Gain

Contrast of the noise function.

This parameter can be overridden using an attribute or texture. To do this, select an option from the drop-down menu next to the parameter.

Bias

Bias the noise towards low or high values.

This parameter can be overridden using an attribute or texture. To do this, select an option from the drop-down menu next to the parameter.

Center Noise Around One

Create noise with an average around 1.0. This is useful for creating attributes that are used as scale factors rather than masks.

With this disabled, noise is in the 0 to 1 range, with it enabled it is 0 to 2.

Fractal Noise

Apply fractal noise on top of the base noise.

Max Octaves

Maximum number of octaves to generate.

Lacunarity

The frequency increment of each successive fractal noise octave.

Roughness

This parameter can be overridden using an attribute or texture. To do this, select an option from the drop-down menu next to the parameter.

Length Mask

Use Length Mask

Mask curves based on their length.

Mode

Controls how curve length is compared against the Length parameter below.

Longer Than

Select curves that are longer than the length specified by Length below.

Same As

Select curves that are about the same length the one specified by Length below.

Shorter Than

Select curves that are shorter than the length specified by Length below.

Normalized Ramp

Maps the length of each curve to ramp parameter. The ends of the ramp correspond to the shortest and longest curve in the input geometry.

Range Ramp

Maps the length of each curve to ramp parameter. The ends of the ramp correspond to the are explicitly specified by the Minimum Length and Maximum Length parameters.

Length

The reference length to compare against.

This parameter can be overridden using an attribute or texture. To do this, select an option from the drop-down menu next to the parameter.

Falloff Range

This parameter can be overridden using an attribute or texture. To do this, select an option from the drop-down menu next to the parameter.

Falloff Decay

This parameter can be overridden using an attribute or texture. To do this, select an option from the drop-down menu next to the parameter.

Minimum Length

The start of the ramp when Mode is set to Range Ramp.

Maximum Length

The end of the ramp when Mode is set to Range Ramp.

Presets

A set of useful presets for the Length Ramp parameter.

Selecting an item from the drop-down applies the preset.

Apply

Apply the selected preset again.

Length Ramp

The ramp that curves are mapped to in Normalized Ramp mode and Range Ramp mode.

Skin Curvature

Use Skin Curvature Mask

Mask curves based on the skin curvature at their root position.

Concave Maximum

The maximum concave curvature to consider. Any curvature beyond this is mapped to the start of the ramp.

Convex Maximum

The minimum convex curvature to consider. Any curvature beyond this is mapped to the end of the ramp.

Smoothing Strength

Smooth curvature values. This can be useful to smooth out spikes in curvature which can be caused by certain topological features.

Presets

A set of useful presets for the Curvature Ramp parameter.

Selecting an item from the drop-down applies the preset.

Apply

Applies the selected preset again.

Curvature Ramp

Curvature is mapped to this ramp. Maximally concave areas are mapped to the start of the ramp, flat areas to the center and maximally convex areas to the end.

Tip

Try out some of the Presets above to get a feeling for how this ramp affects the mask.

Geometry Mask

Use Geometry Mask

Mask curves on the inside or outside of a surface geometry connected to the fourth input.

Voxel Size

The voxel size used to generate a VDB SDF representation of the connected geometry.

Interior Range

Controls how far into the interior of the surface the mask is applied. The band specified by exterior range and interior is mapped to the Depth Ramp below.

Exterior Range

Controls how far outside of the surface the mask is applied. The band specified by exterior range and interior is mapped to the Depth Ramp below.

Presets

Applies useful presets to the Depth Ramp.

Depth Ramp

Blur Voxel Values

Blur the generate mask volume.

Blur Radius

Blur voxel values within this radius.

Blur Iterations

The number of times to blur voxel values.

Random Mask

Use Random Mask

Mask a percentage of randomly selected primitives.

Previous Masks

Controls how other masks influence are combined with the random values.

Multiply Fraction And Value

The fraction is multiplied with any other masks, meaning fewer primitives will be selected in areas that have low mask values.

The output mask value is also multiplied by the previous mask values.

Multiply Fraction

The fraction is multiplied with any other masks, meaning fewer primitives will be selected in areas that have low mask values.

The output value of selected primitives is not influenced by previous masks. It is purely defined by the Variation, and Gain parameters of the random mask.

Multiply Value

The defined by the Fraction parameter is used as is. Only the output values are multiplied with the previous mask values.

Seed

The seed value to use for the random mask. This is combined with the primitive number or the 'id' attribute of the primitive to generate random values.

Fraction

The fraction of primitives select. 1.0 selects all primitives.

Variation

Creates some variation in the output values of selected primitives. At 0.0, all primitives are set to a mask value of 1.0.

Gain

The contrast of output values when Variation is set to a value higher than 0.0.

Curve Mask

Use Curve Mask

Mask curves along their length using a ramp parameter.

Range In Absolute Length

Range Min and Range Max are specified in terms of the length of the curve, rather than as normalized value between 0.0 and 1.0 for the start and end of each curve.

Range Min

Specifies the start position of the Curve Mask Ramp along the length of the curve.

Range Max

Specifies the end position of the Curve Mask Ramp along the length of the curve.

Effect Position

Specifies the position where the highest mask value is applied within the range.

Falloff

Specifies how the ramp drops of from the peak point.

Influence Width

Specifies how wide the area of influence is.

Curve Mask Ramp

Controls how point along the length of the curve is affected. This can be controlled directly or set via the parameters above.

See also

Geometry nodes