Houdini 20.0 Nodes Geometry nodes

Crowd Assign Layers geometry node

Assigns layers to a crowd to produce geometry variations.

Since 19.0

This SOP creates random combinations of layers which are assigned to each agent in the crowd, producing geometry variations.

When building the agent definition, the Agent Layer SOP can be used to create the layers (sets of shapes) that are used by this SOP after populating the crowd.



Specifies which agent primitives are affected by this SOP’s operations. Each assignment can modify a subset of this group.

Layer List

Specifies whether to edit the agent’s list of current layers, or its list of collision layers.

Remove Layers

Removes any of the agent’s assigned layers which match this pattern. For example, a value of * will remove all of the layers assigned to the agent before applying the new layer assignments.

Switch Layers

Switches the assigned layers using one or more search/replace patterns. This can be useful for e.g. switching agents from proxy layers to high-res layers. The standard pattern renaming syntax from the replace_match function is used. For example, if From is *_to_* and To is *-*, a layer named ab_to_cd will become ab-cd.


The string pattern to rename.


The replacement pattern for the string.

Number of Assignments

Performs layer assignments (from a weighted distribution) to a group of agents.


Toggles whether the layer assignment is performed.

Select By

Specifies how to select the agents for this layer assignment. The agents can be selected by specifying a group, or by matching against the agent’s list of current layers or collision layers.


Specifies a subgroup of agents to assign a layer to.

Layer Pattern

A layer will be assigned to the agent if at least one of the layers already assigned to the agent matches this pattern. This includes earlier assignments made by this SOP.

Percent to Select

If enabled, the layer assignment is only applied to a percentage of the selected agents.

Random Seed

Seed for the random selection of agents performed when Percent to Select is enabled.

Random Seed

Seed for the random layer selection.

Layer Choices

Specifies a weighted random distribution of layers.


Specifies one or more layer names. The associated Weight value is divided evenly between the layers matching this pattern.


Specifies how likely the layers are to be selected.

See also

Geometry nodes