Houdini 20.0 Nodes Object nodes

Alembic Archive object node

Loads the objects from an Alembic scene archive (.abc) file into the object level.

Since 11.1


Build or update hierarchy

Click to read the archive file in File name and build a hierarchy of Houdini objects from the objects in the archive.

Build Hierarchy Using Subnetworks

The Alembic Archive will import the alembic objects either using subnetworks (i.e. children contained in a subnet), or by wiring the nodes in a hierarchy (i.e. a single network).

Build Hierarchy With Channel References

When building Houdini objects, create channel references to the root Alembic archive. This means that any changes you make to the Alembic Archive’s parameters will be picked up automatically by children. However, there will be potentially thousands of channel evaluations.

With no channel references, you can propagate parameter changes on the Alembic archive to the child objects using Push Parameters To Children.

Load Hierarchy As One Single Geometry

Instead of creating Houdini objects for each Alembic transform and shape, this will load the Alembic archive into a single geometry node.


This will still create Houdini objects for Alembic cameras.

Flatten Visibility Evaluation

In Houdini, when a subnetwork’s display is turned off, all its children will also not be displayed. Alembic allows children of a network to be displayed, even when the parent is not displayed.

Flattening visibility forces each object to determine its own visibility rather than relying on parents. This is slightly more costly, but will reproduce Alembic’s visibility model.

Push Parameters to Children

Propagate changes to parameters to the child objects (see Build Hierarchy With Channel References).

Reload Geometry

Clear the Alembic cache and reload fresh geometry for all the shapes without rebuilding or updating the archive hierarchy.


Compared to Build or Update Hierarchy, this is the faster way to update an Alembic archive version when there is no hierarchy change.

Number of Layers

Use this multiparm to apply Alembic layers.

File name

Path to the Alembic archive (.abc) file.

Object Path

A path to one or more objects inside the archive. If specified, the node will load only these object and their children. The default is blank, which means load all the geometry in the archive.


The Alembic frame at which to sample the geometry. The default value is $F (Houdini’s current frame). If you need to offset the start time of the animation in the archive, you can add or subtract frames (e.g. $F + 48).

Frames per second

Combined with the Frame parameter, this is used to convert Alembic’s time-based animation to Houdini frames. The default is $FPS (Houdini’s current frames-per-second setting). If the archive file was created with a different FPS, you will need to enter it here.

Load As

How to load the Alembic geometry into Houdini:

Alembic Delayed Load Primitives

These custom primitives are very light-weight and will display faster in the viewport. They are not as full featured as other Houdini primitive types (i.e. ray-tracing is not very accurate), but can be converted to other primitive types if need be.

Unpack Alembic Delayed Load Primitives

Load the geometry as Alembic packed primitives and then automatically unpack the geometry to create native Houdini geometry.

Load Houdini Geometry

Convert the Alembic primitives to use native Houdini geometry.

Houdini Point Cloud

Load the P attribute from the Alembic primitives as a Houdini point cloud. Currently, this doesn’t load any attributes other than P.

Bounding Boxes

Load only the bounding boxes of the Alembic primitives.

Display As

How the Alembic geometry is displayed in the viewport.

Full Geometry

The Alembic geometry is fully displayed.

Point Cloud

Only the points are displayed.

Bounding Box

Only the geometry bounding boxes are displayed.


Only the geometry centroid is displayed.


No geometry is displayed.

User Properties

How Alembic user properties should be handled.

Do Not Load

User properties are not loaded.

Load Values Only

User property values are loaded as a JSON dictionary into a primitive string attribute.

Load Values and Metadata

User property values are loaded as a JSON dictionary into a primitive string attribute. User property metadata, useful for interpreting and processing the values, is loaded as a JSON dictionary into a separate primitive string attribute.

Remap attributes

Use this multiparm to rename Alembic point, vertex, and/or primitive attributes to their Houdini equivalents and optionally change their type info. For example, remapping MyColor to Cd (diffuse color). Click the + button to add a new mapping.

Object nodes

  • Agent Cam

    Create and attach camera to a crowd agent.

  • Alembic Archive

    Loads the objects from an Alembic scene archive (.abc) file into the object level.

  • Alembic Xform

    Loads only the transform from an object or objects in an Alembic scene archive (.abc).

  • Ambient Light

    Adds a constant level of light to every surface in the scene (or in the light’s mask), coming from no specific direction.

  • Auto Bone Chain Interface

    The Auto Bone Chain Interface is created by the IK from Objects and IK from Bones tools on the Rigging shelf.

  • Blend

    Switches or blends between the transformations of several input objects.

  • Blend Sticky

    Computes its transform by blending between the transforms of two or more sticky objects, allowing you to blend a position across a polygonal surface.

  • Bone

    The Bone Object is used to create hierarchies of limb-like objects that form part of a hierarchy …

  • Camera

    You can view your scene through a camera, and render from its point of view.

  • Common object parameters

  • Dop Network

    The DOP Network Object contains a dynamic simulation.

  • Environment Light

    Environment Lights provide background illumination from outside the scene.

  • Extract Transform

    The Extract Transform Object gets its transform by comparing the points of two pieces of geometry.

  • Fetch

    The Fetch Object gets its transform by copying the transform of another object.

  • Formation Crowd Example

    Crowd example showing a changing formation setup

  • Fuzzy Logic Obstacle Avoidance Example

  • Fuzzy Logic State Transition Example

  • Geometry

    Container for the geometry operators (SOPs) that define a modeled object.

  • Groom Merge

    Merges groom data from multiple objects into one.

  • Guide Deform

    Moves the curves of a groom with animated skin.

  • Guide Groom

    Generates guide curves from a skin geometry and does further processing on these using an editable SOP network contained within the node.

  • Guide Simulate

    Runs a physics simulation on the input guides.

  • Hair Card Generate

    Converts dense hair curves to a polygon card, keeping the style and shape of the groom.

  • Hair Card Texture Example

    An example of how to create a texture for hair cards.

  • Hair Generate

    Generates hair from a skin geometry and guide curves.

  • Handle

    The Handle Object is an IK tool for manipulating bones.

  • Indirect Light

    Indirect lights produce illumination that has reflected from other objects in the scene.

  • Instance

    Instance Objects can instance other geometry, light, or even subnetworks of objects.

  • LOP Import

    Imports transform data from a USD primitive in a LOP node.

  • LOP Import Camera

    Imports a USD camera primitive from a LOP node.

  • Labs Fire Presets

    Quickly generate and render fire simulations using presets for size varying from torch to small to 1m high and low

  • Light

    Light Objects cast light on other objects in a scene.

  • Light template

    A very limited light object without any built-in render properties. Use this only if you want to build completely custom light with your choice of properties.

  • Microphone

    The Microphone object specifies a listening point for the SpatialAudio CHOP.

  • Mocap Acclaim

    Import Acclaim motion capture.

  • Mocap Biped 1

    A male character with motion captured animations.

  • Mocap Biped 2

    A male character with motion captured animations.

  • Mocap Biped 3

    A male character with motion captured animations.

  • Null

    Serves as a place-holder in the scene, usually for parenting. this object does not render.

  • Path

    The Path object creates an oriented curve (path)

  • PathCV

    The PathCV object creates control vertices used by the Path object.

  • Python Script

    The Python Script object is a container for the geometry operators (SOPs) that define a modeled object.

  • Ragdoll Run Example

    Crowd example showing a simple ragdoll setup.

  • Reference Image

    Container for the Compositing operators (COP2) that define a picture.

  • Rivet

    Creates a rivet on an objects surface, usually for parenting.

  • Simple Biped

    A simple and efficient animation rig with full controls.

  • Simple Female

    A simple and efficient female character animation rig with full controls.

  • Simple Male

    A simple and efficient male character animation rig with full controls.

  • Sound

    The Sound object defines a sound emission point for the Spatial Audio chop.

  • Stadium Crowds Example

    Crowd example showing a stadium setup

  • Stereo Camera Rig

    Provides parameters to manipulate the interaxial lens distance as well as the zero parallax setting plane in the scene.

  • Stereo Camera Template

    Serves as a basis for constructing a more functional stereo camera rig as a digital asset.

  • Sticky

    Creates a sticky object based on the UV’s of a surface, usually for parenting.

  • Street Crowd Example

    Crowd example showing a street setup with two agent groups

  • Subnet

    Container for objects.

  • Switcher

    Acts as a camera but switches between the views from other cameras.

  • TOP Network

    The TOP Network operator contains object-level nodes for running tasks.

  • VR Camera

    Camera supporting VR image rendering.

  • Viewport Isolator

    A Python Script HDA providing per viewport isolation controls from selection.

  • glTF