Houdini 20.0 Nodes Render nodes

Mantra Archive render node

Generates disk-based archives which can be used by mantra.

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Archives allow Houdini to be more efficient when generating scripts for renderers since: a) Houdini can have different geometry displayed b) Houdini doesn’t have to send the geometry down to the renderer every frame.

Mantra archives are stored as geometry files (typically .bgeo files) and material archive files.

Arguments may be passed to the script and variable expansion is done before calling the script.


Save to Disk

Begins generation of archives.


Opens the render control dialog to allow adjustments of the render parameters before generating archives.

Valid Frame Range

Controls whether this render node outputs the current frame (Render any frame) or the image sequence specified in the Start/End/Inc parameters (Render Frame Range).

Render Frame Range (strict) will render frames START to END when it is rendered, but will not allow frames outside this range to be rendered at all. Render Frame Range will allow outside frames to be rendered. This is used in conjunction with render dependencies. It also affects the behavior of the 'Override Frame Range' in the Render Control dialog.

Two possible cases where you'd want the strict behavior:

  • A 60 frame walk cycle written out to a geo, but part of a larger ROP net to render out a larger frame range.

  • A texture loop from 1-20.

Otherwise, you will usually set this to non-strict.

Render Current Frame

Archives a single frame, based on the value in the playbar or the frame that is requested by a connected output render node.

Render Frame Range

Archives a sequence of frames. If an output render node is connected, this range is generally ignored in favor of frames requested by the output render node.

Render Frame Range (Strict)

Archives a sequence of frames. If an output render node is connected, this range restricts its requested frames to this frame range.


Specifies the range of frames to archive (start frame, end frame, and increment). All values may be floating point values. The range is inclusive.

These parameters determine the values of the local variables for the output driver.

For example, if the parameters are set to: table>>

There will be 4 frames archived (10.5, 11, 11.5, and 12), so $NRENDER will have a value of 4. $N will have the value: table>>

Render With Take

The output driver will switch to this take before rendering and then restore the current take when rendering is done.


use chs("take") to use this value in other parameters. See the chs expression function for more information.


Create Intermediate Directories

When turned on, creates intermediate parent directories for output files as needed. Currently only applies to generated scripts, images, and shadow maps.

Initialize Simulation OPs

Forces all simulation OPs to be reset. This includes DOP Networks, POP SOPs, and other OPs that cache their results.

Objects to Archive

Specifies the number of objects to archive (the number of objects in the multi-parm).

Disable generation of archive 1

Disables the inclusion of this object in the archive without having to delete the multi-parm parameter.

Object 1

The object to put into the archive.

Geometry File 1

The disk file in which the object should be stored. If the same disk file is specified for multiple parameters, only the first object will be stored in the archive.

Material File 1

When a SOP has materials applied, you can optionally save out the material properties to a separate file. This file can be used by the mantra delayed load procedural SHOP.


You can add any rendering property to the mantra archive node. Properties change the behavior of how mantra will interpret the scene. You can add any property, even if it might not make sense to add to an output driver. For example, you can add a surface shader even though the output driver does not have any surfaces. These values will be used as default values for objects which do not have these properties defined. However, if an object has a property defined, the value assigned to the object will be used instead of the value assigned on the output driver.


Each script command refers to an hscript command which will be run, regardless of the expression language selected for the parameter. The resulting string will be run as an hscript command.


It is possible to use the python, unix or source hscript commands to perform complex processing.

The commands are always run when rendering occurs. The command checks the parameters of the output driver when it is rendering a range or sending output to a command.

Before the render occurs, Houdini will automatically set the current hscript directory to point to the output driver.

Pre-Render Script

This command is run before any IFDs are generated. It is only run once per render.

Pre-Frame Script

This command is run before each IFD is generated.

Post-Frame Script

This command is run after each IFD is generated.


Although the IFD may have been generated, this does not necessarily mean that mantra has finished rendering the image when this command is run.

Post-Render Script

This command is run one time, after all IFDs have been generated.


Although the IFD may have been generated, this does not necessarily mean that mantra has finished rendering the image when this command is run.



The current frame of the range specified. This always starts at 1.


Total number of frames being rendered.

See also

Render nodes

  • Agent

    This output operator is used to write agent definition files.

  • Alembic

    Exports the scene to an Alembic archive. Alembic is a common exchange format for moving geometry and animation between different 3D software packages.

  • Archive Generator

    Generates disk-based archives which can be used by either mantra or RIB renderers.

  • Bake Animation

    Bakes animation from object transforms and CHOP overrides.

  • Bake Texture

    Generates a texture map from one or more objects' rendered appearance.

  • Batch

    Renders the input ROP in a single batch job.

  • Channel

    The Channel output operator generates clip files from a particular CHOP.

  • Composite

    Renders images from a compositing network.

  • DSM Merge

    Merges two or more deep shadow/camera map files.

  • Dem Bones Skinning Converter

    Converts any non-changing topology deforming mesh sequence into a bone-based animation.

  • Dynamics

    Saves the state of a DOP network simulation into files.

  • Fetch

    Makes a dependency link to a ROP in a different network.

  • Filmbox FBX

    Exports entire scenes to FBX files.

  • Filmbox FBX Animation

    Export animation from geometry-based skeleton to an FBX file.

  • Filmbox FBX Character

    Export a skinned character with geometry-based skeleton to an FBX file.

  • Frame Container

    Prevents frame dependency changes in the contained nodes from affecting its inputs.

  • Frame Depedency

    Allows an output frame to depend on one or more input frames.

  • GLTF Character

  • Geometry

    Generates geometry files from a SOP or DOP network.

  • Geometry Raw

    Generates raw binary files from a SOP or DOP network.

  • HQueue Render

    HQueue, or Houdini Queue, is a distributed job scheduling system.

  • HQueue Simulation

    HQueue, or Houdini Queue, is a distributed job scheduling system.

  • Hair Card Texture

    Renders hair textures for use on hair cards.

  • Karma

    Renders non-USD scenes using Houdini’s Karma renderer.

  • Labs 3D Facebook Image

    Quickly render a 3D scene to a 2.5D image that can be uploaded to Facebook.

  • Labs Flipbook Textures

    Renders, composites, and exports flipbook textures.

  • Labs JSON Exporter

    Export geometry attibutes to a JSON file.

  • Labs Marmoset Export

    The Marmoset Export ROP allows you to quickly generate an mview inside Houdini

  • Labs Niagara ROP

    Export point caches to be used with Unreal’s Niagara particle system.

  • Labs Sketchfab

    Uploads geometry to Sketchfab

  • Labs Vertex Animation Textures

    The Vertex Animation Textures ROP will export a mesh and a set of textures to be used with a shader for complex real-time effects, such as: soft-body deformation, rigid-body dynamics, dynamically remeshed geometries, and particle sprites.

  • MDD Point Cache

    This output operator is used to write an MDD animation file.

  • Mantra

    Renders the scene using Houdini’s standard mantra renderer and generates IFD files.

  • Mantra Archive

    Generates disk-based archives which can be used by mantra.

  • Merge

    Merges several render dependencies into one.

  • Net Barrier

    Blocks the ROP network until synchronization occurs.

  • Null

    Does nothing.

  • OpenGL

    Render an image using the hardware-accelerated 3D viewport renderer.

  • Pre Post

    Renders ROPs before and after a main job.

  • Shell

    Runs an external command.

  • Subnetwork

    The SubNetwork output operator provides an easy way to manage large number of output operators.

  • Switch

    Renders one of several inputs.

  • Tractor

    Tractor is a program shipped out with Pixar’s distribution of RenderMan.

  • USD

    Renders a LOP network out to one or more USD files. This node is available as render node or as a LOP.

  • USD Render

    Renders an output image from the stage generated by a LOP network.

  • USD Stitch

    Merges USD files representing individual frames by composing them.

  • USD Stitch Clips

    Merges multiple value clips representing individual frames.

  • USD Zip

    Assembles USDZ archive files from existing USD files.

  • Wedge

    Re-renders the same ROP multiple times with different settings

  • Wren

    This output operator is used to drive the Wren rendering program.

  • glTF