Houdini 22.0 Nodes LOP nodes

Scatter Instances

Hydra generative procedural and LOP node for scattering instances.

Since 22.0

This node provides a way to configure scatter instances from within LOPs. It is also a hydra generative procedural, meaning the configured scatter is computed at render-time. It provides controls for scattering instances, randomly transforming each instance, and assigning prototypes.

In addition to offering random primvar values, there are some built-in primvars available to use within a material, to get shading variation:

id

Integer value unique to each instance.

protoid

Integer value corresponding to each prototype across all groups.

protogroup

Integer value of each prototype group, starting from 0.

Parameters

Primitive Path

The scene graph path at which to create the generative procedural prim.

Execution Mode

Sets whether the scatter procedural should be executed at render-time in Hydra, or author the pointinstancer immediately. Generally, the results in the rendered frame should be indistinguishable from one another, apart from small calculation differences.

Deferred

The scattering process is not computed in LOPs, instead Engine executes the scattering within a Hydra Scene Index.

Immediate

The scattering process is executed as part of the LOP node cook, and the resulting instances are all authored to the stage.

Up Axis

The direction of the scene’s up axis, for purposes of computer the instance scattering and transforms.

Enable Camera

Use a camera as part of the scattering procedural.

Camera Path

The scene graph path of the camera used for computing the scatter procedural. When cameras are enabled, but no path is specified, the current render camera is used instead.

Source Geometry

Prim Pattern

The primitives onto which instances will be scattered.

Geometry Type

Animation (Beta)

Scatter on transforming and deforming surfaces. Not fully supported yet.

Input Primvars

Rest Primvar

The name of the primvar to use for rest space.

Texture Coordinates

TexCoord Source

Geometry

Texture coordinates primvar authored on the scatter target geometry.

Camera Projection

Texture coordinates are projected from the camera onto the scatter target geometry.

TexCoord Primvar

Name of the texture coordinate primvar.

Scattering

Point Count Method

How the number of instance points is determined and computed. Note that even when scattering a specific number, masks or other control signals may affect the final number of instances.

Number

Scatters an absolute number of points across the target geometry.

Density

Roughly the number of points per area unit, distributed across the target geometry.

Face Centroids

Creates a single point for each polygon on the scatter target geometry.

Number of Instances

Scatter Count

The base number of points to be scattered on the target geometry.

Enable Scatter Count Map

Scales the number of points by a texture map.

Texture Map

The image of float values that scale the number of scattered points.

Enable Scatter Count Primvar

Scales the number of points by a primvar on the scatter target geometry.

Primvar

The name of the float primvar to adjust the number of points scattered.

Instance Density

Density

The base density of points across the surface.

Enable Scatter Density Map

Use a texture map to scale the scatter density.

Texture Map

The image of float values that scale the scattered point density.

Enable Scatter Density Map

Scales the scattered point density by a texture map.

Primvar

Scales the density of points by a float primvar on the scatter target geometry.

Scatter in Texture Space

The name of the float primvar to adjust the scattered point density.

Face Centroids

Enable Map

Use a texture map to hide or show an instance on a given mesh face.

Texture Map

The image of float or integer values that hide or show an instance on a given mesh face.

Enable Primvar

Use a primvar to hide or show an instance on a given mesh face.

Primvar

The float or integer values that hide or show an instance on a given mesh face.

Max Point Limit

The maximum number of points that can be scattered by the procedural.

Relax Iterations

Number of iterations used to relax the scattered points.

Seed

Seed used to control the distribution of points.

Masks

Up Axis Direction

Up Axis Direction

Whether to calculate a mask using the angle between the surface geometry and the up axis.

Max Angle

Maximum angle between the surface normal and up-axis, at which to scatter points on the target geometry.

Reverse Direction

Reverses the up axis direction.

Cast Shadows

Points will not be scattered in areas covered by target geometry features.

Invert

Inverts the mask effect.

Ambient Occlusion

Ambient Occlusion

Whether to calculate an ambient occlusion mask on the surface geometry.

Maximum Ray Distance

Maximum distance in world units to cast rays and test for surfaces.

Input Min

Minimum occlusion sets the mask to 0.

Input Max

Maximum occlusion sets the mask to 1.

Invert

Inverts the mask effect.

Camera

Enable Camera Mask

Use the specified Camera to control the distribution of points.

Frustum Padding

Expand or contract the camera frustum mask.

Enable Camera Mask Near

Manually set the camera mask near plane.

Override Near Plane

Manually set the camera mask near plane.

Enable Camera Mask Far

Manually set the camera mask far plane.

Override Far Plane

Manually set the camera mask far plane.

Invert

Inverts the mask effect.

PointInstancers

Enable Points Mask

Whether to calculate a mask around pointinstancers.

Prim Pattern

PointInstancer primitives to use for the mask calculation. Cannot specify individual instances.

Radius

Distance from each instance to include in the mask.

Falloff

Additional soft distance beyond the radius.

Use Widths/Radius Attribute

Uses the authored instance scale as the base value.

Invert

Inverts the mask effect.

Meshes

Enable Objects Mask

Whether to calculate a mask from a series of mesh objects.

Prim Pattern

Mesh primitives to use in the mask calculation.

Offset

Offset the mask from each object in the mask.

Falloff

Additional soft distance beyond the offset.

Bounding Box Only

Uses the extents of each object, instead of the meshes themselves.

Invert

Inverts the mask effect.

Transforms

Orient to Surface

Surface Blend

Blends each instance’s local up-axis between the up axis direction and the surface normal.

Blend Variation

Variation of Surface Blend on each instance.

Spread Angle

Additional range of orientation for each instance.

Spin

Enable Spin Primvar

Whether to use a primvar to set the initial facing direction.

Direction Primvar

The vector primvar to provide the initial facing direction.

Spin

Rotation around the instance local up axis to set the direction. Same value is used across all instances.

Variation

Amount of variation to the spin value for each instance.

Increments

Rounds the spin values to specific incremental values.

Enable Spin Map

Whether to use a texture map to multiply against each instance’s spin.

Spin Map

The image of values to multiply the spin for each instance.

Scale

Use Scale from Scatter

Whether to use computed scale from the scattering.

Scale

Scale value applied to all of the instances.

Variation

Amount of variation to the scale value for each instance.

Enable Scale Map

Whether to use a texture map to multiply against each instance’s scale.

Texture Map

The image of values to multiply the scale for each instance.

Position

Peak Offset

Amount to offset the instances along their local up axis.

Peak Variation

Amount of variation to the peak value for each instance.

Enable Peak Map

Whether to use a texture map to multiply against each instance’s peak.

Texture Map

The image of values to multiply the vertical peak offset for each instance.

Seed

Seed used only for the transform values, but does not cause any re-calculation of anything except the transforms.

Prototypes

Add Prototypes from Second Input

Copies prototypes from the second input for use in prototype groups.

Method

The method to use for select the prototype group used by each instance. Within a prototype group, the selection is random if more than 1 prototype is specified. There are 3 methods for assigning prototypes and prototype groups.

Weights

Each group is a primitive pattern, and each group is weighted individually.

Texture Maps

Values in the texture map correspond to each prototype group index.

Primvars

Primvar values across the scatter target geometry correspond to each prototype group index.

Prototype Groups

Prim Pattern

The pattern of primitives used for the prototype group.

Weight

Sets the probability this prototype group will be selected. Only applies between prototype groups, within any group that specifies multiple primitives, the final prototype assignment is random.

Shading

Assign Material

Whether to assign a material to the procedural primitive. By default this material will only apply to objects that don’t already have a material defined lower in the scene graph.

Bind Material

Material Path

Path to the material primitive.

Purpose

Whether the material binding applies to preview, render, or all display purposes.

Strength

Specifies the material binding strength. The default binding strength is the same as Weaker than Descendants. Set to Stronger than Descendants to override the materials set on the prototypes.

Random Primvars

Randomly generates primvar value useful for shading variation.

Seed

Seed to adjust randomization of the shading primvars only.

See also

LOP nodes

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    Authors APEX rigs and binds them to USD primitives.

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  • Additional Render Vars

    Create multiple render vars.

  • Asset Reference

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  • Assign Material

    Assigns a material to one or more USD primitives. You can use also programmatically assign materials using VEX, programmatically override material settings for each assignment, and programmatically assign materials to geometry subsets.

  • Assign Prototypes

    Switch point instances or USD instanceable prims to instance a different prototype.

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  • Attribute Wrangle

    Create/edit USD primitive attributes using a VEX snippet.

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    Automatically selects a level-of-detail variant based on the primitive’s distance from the camera.

  • Bake APEX Scene

    Bakes animation from APEX scenes to point positions and transforms.

  • Bake UsdSkel Skinning

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    This node begins a block of LOP nodes, within which certain context options have certain values.

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    Blends transforms according to a list of weights specified as parameters.

  • Cache

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    Adds a USD camera to the scene.

  • Capsule

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  • Collection

    Creates/edits collections using primitive patterns.

  • Component Geometry

    Geometry container or import source, in a network created by the Component Builder tool.

  • Component Geometry Variants

    Sets up geometry variants, in a network created by the Component Builder tool.

  • Component Material

    Assigns materials to geometry in a network created by the Component Builder tool.

  • Component Output

    Assembles the final Component prim, in a network created by the Component Builder tool.

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    Configures and attaches simple APEX rigs to USD primitives.

  • Configure Guide Deform

    Tags groom primitives with the HairDeform procedural API, configuring how they deform at render time.

  • Configure Layer

    Edits metadata on a layer.

  • Configure Primitives

    Edits various metadata on one or more primitives.

  • Configure Properties

    Configures metadata on properties (relationships and attributes).

  • Configure Stage

    Configures metadata for how to load layers into the stage and asset resolution.

  • Coordinate System

    Define named coordinate systems used in shaders.

  • Copy Property

    Copy properties from one primitive to another, or renames properties on a primitive.

  • Copy to Points

    Instances or copies primitives onto points.

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  • Cube

    Creates or edits a cube shape primitive.

  • Cylinder

    Creates or edits a cylinder shape primitive.

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  • Draw Mode

    Sets draw mode properties on USD model assets.

  • Drop

    Runs a simulation to drop primitives under gravity.

  • Duplicate

    Creates copies of a prim (and its descendants).

  • Edit

    Interactively transforms prims in the viewer. Can use physics collisions to position props realistically.

  • Edit Context Options

  • Edit Material Network

    Allows you to edit an existing USD material by modifying parameters and shader connections. This can be useful if the existing material is on a non-editable layer.

  • Edit Material Properties

    Lets you build a spare parameter interface that reflects material or shader input attributes to directly edit their values.

  • Edit Properties

    Lets you build a spare parameter interface to directly edit attribute and relationship values.

  • Edit Properties From Node

    Lets you refer to the parameter on another node to directly edit attribute and relationship values.

  • Edit Prototypes

    Modify the prototypes of native or point instances in-place, without disturbing the instancing setup.

  • Edit Target Layer

    Allows you to apply edits directly in a lower layer, instead of overriding prims and attributes in the active layer.

  • Error

    Generates a message, warning, or error, which can show up on a parent asset.

  • Explore Variants

    Visualize, set, or extract variants on primitives.

  • Extract Instances

    Converts (heroes) an instance into a real editable prim.

  • Fetch

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  • File Cache

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  • Follow Path Constraint

    Constrains a prim to follow a path curve.

  • For Each

    The end node of a For-Each loop block.

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  • Geometry Sequence

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  • Geometry Subset VOP

    Creates USD geometry subsets within geometry prims (similar to groups in SOPs) based on evaluating a VEXpression or VOP network.

  • Graft Branches

    Takes prims/branches from the second input and attaches them onto branches of the scene graph tree in the first input.

  • Graft Stages

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  • Houdini Procedural: Hair

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  • Houdini Procedural: Ocean

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  • Houdini Procedural: RBD

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  • Image Filter

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    Parses usda code representing a layer and adds it to the layer stack.

  • Insertion Point

    Represents a point in the node graph where nodes can be inserted.

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  • Karma Render Products

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  • Karma Render Settings

    Configure Render Settings for Karma.

  • Karma Shadow Catcher

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  • Karma Sky Atmosphere

    Creates or edits a Karma Sky Atmosphere.

  • Karma Sky Dome Light

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  • Karma Standard Render Vars

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  • Karma Texture Baker

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  • Labs Karma

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  • Labs Karma AOVs for RenderMan Denoiser

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  • Labs ML CV Synthetics Karma Rop

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  • Labs ZibraVDB Import

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  • Layer Replace

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  • Light

    Creates or edits a USD Light prim. This node also adds some useful Karma-specific attributes.

  • Light Filter Library

    Authors USD light filter primitives from VOP nodes.

  • Light Linker

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  • Light Mixer

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  • Live Render

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  • Load Layer for Editing

  • Loft Payload Info

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  • Look At Constraint

    Constrains a prim to always point toward a target.

  • Mask from Bounds

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  • Match Size

    Resizes and recenters the input geometry to match a reference bounding box.

  • Material Library

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  • Material Linker

    Creates material assignments based on rules.

  • Material Variation

    Creates attributes/primvars to override material parameters per-prim/instance.

  • Merge

    Merges the layers from incoming stages into a unified layer stack.

  • Merge PointInstancers

    Merges point instancers into a single consolidated point instancer.

  • Mesh

    Creates or edits a mesh shape primitive.

  • Modify Paths

    Modify asset path attribute values.

  • Modify Point Instances

    Modifies point transforms and property values for individual point instances.

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  • Output

    Represents the output of a subnetwork. Allows you to design a node asset with multiple outputs.

  • Paint Instances

    Provides tools for populating a scene with USD assets in a point instancer. You can place individual instances, paint/scatter instances in different ways using customizable brushes, and edit existing instances.

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  • Plane

    Creates or edits a plane shape primitive.

  • PointInstancer

    Creates or edits USD PointInstancer prims from SOP points.

  • Points

    Creates or edits a Points shape primitive.

  • Points Constraint

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  • Primitive

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  • Python Script

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  • Reference

    References the contents of a external USD files and/or layers created by other LOP nodes into a branch of the existing scene graph tree. Can also remove or replace existing references.

  • Relocates

    Authors relocate source-target mappings to the active layer.

  • Render Geometry Settings

    Applies renderer-specific geometry settings to geometry in the scene graph.

  • Render Pass

    Creates or edits a UsdRenderPass prim, which represents a render pass, with attributes configuring the content of the pass, and how to configure the renderer to generate the pass.

  • Render Product

    Creates or edits a UsdRenderProduct prim, which represents an output of a renderer (such as a rendered image file or other file-like artifact produced by a renderer), with attributes configuring how to generate the product.

  • Render Settings

    Creates or edits a UsdRenderSettings prim, which holds the general settings for rendering the scene.

  • Render Var

    Specifies a custom variable computed by the renderer and/or shaders, either a shader output or a light path expression (LPE).

  • Resample Transforms

    Generates interpolated transform time samples from existing time samples on USD prims.

  • Restructure Scene Graph

    This node has various operations for editing prim paths, variant sets, and composition arcs.

  • Retime Instances

    Offsets and/or scales the timing of animation on selected instances.

  • SOP Create

    Lets you create geometry in a SOP subnetwork inside this node, so you can create geometry in-place in the LOP network instead of needing a separate SOP network.

  • SOP Import

    Imports geometry from a SOP network into the USD scene graph.

  • SOP Import APEX Scene

    Imports an APEX scene or character from a SOP network into the USD scene graph.

  • SOP Import Crowd

    Imports a crowd from a SOP network into the USD scene graph.

  • SOP Import UsdSkel Character

    Imports a character or animation from a SOP network into the USD scene graph.

  • SOP Modify

    Converts USD geometry into SOP geometry, runs the SOP subnet inside this node on the geometry, and converts the changes back to USD overrides.

  • Scatter Instances

    Hydra generative procedural and LOP node for scattering instances.

  • Scene Doctor

    Validates primitives on a USD stage.

  • Scene Import

    Imports models, materials, and lights from the Object level into the LOP network.

  • Scope

    Creates a scope primitive. Scope is the simplest form of grouping, and does not have a transform. Scopes can be useful for organizing the scene tree.

  • Set Extents

    Sets the bounding box metadata of selected primitives.

  • Set Variant

    Selects (switches to) one of the variants stored in a variant set on a primitive.

  • Shot Layer Edit

    Part of the Shot Builder Toolset, targets a specific layer for all shots that match the give pattern.

  • Shot Load

    Part of the Shot Builder Toolset, load USD data for your project.

  • Shot Output

    Part of the Shot Builder Toolset, outputs USD data and /or rendered images to your project.

  • Shot Split

    Passes through the input node’s stage, but may alter the shot context option depending on which output branch is being cooked.

  • Shot Switch

    Passes through one of several inputs, based on the shot context option.

  • Simulation Proxy

    Generates low-poly collison geometry suitable for physical simulation and creates a proxy relationship to the original model.

  • Sphere

    Creates or edits a sphere shape primitive.

  • Split PointInstancers

    Splits a point instancer into two or more instances, which divide up the original instances.

  • Split Primitive

    Splits USD geometry prims into child primitives based on geometry subsets or primvar values.

  • Split Scene

    This node splits a scene graph into two disjoint sets of primitives.

  • Stage Manager

    Provides a convenient interface to reference in many files at once and place them in the scene graph tree.

  • Store Parameter Values

    Lets you store temporary (unsaved) data in the stage.

  • Sublayer

    Imports from USD files or other LOP node chains into as sublayers, or removes/replaces/reorders existing sublayers.

  • Subnet

    Encapsulates a LOP subnetwork, allowing you to organize and hide parts of the network.

  • Surface Constraint

    Constrain a prim to stick to a surface.

  • Switch

    Passes through one of several inputs, based on a parameter choice or expression.

  • Texture Material Library

    Authors USD material primitives whose texture inputs are driven by COPs.

  • TimeShift

    Outputs the stage as it is at a different point in the timeline.

  • Transform

    Edits the transforms of selected USD primitives.

  • Transform UV

    Moves, rotates, and scales texture coordinates on USD primitives.

  • Transform by SOP Points

    Transforms USD primitives by SOP points with transform attributes.

  • USD ROP

  • USD Render ROP

  • Unassign Material

    Unbinds a material from one or more USD primitives.

  • Value Clip

  • Vary Material Assignment

    Assign different materials across a number of prims to create variation.

  • Volume

    References volume data on disk into a volume prim containing field prims.

  • Xform

    Creates or edits an Xform prim. Xform (and its sub-classes) represents a transform in the scene tree.