Houdini 18.5 Nodes Render nodes

USD Render render node

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

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Since 18.0

Overview

This node writes the USD generated by a LOP network to a temp file, then launches an external process (by default, husk) to render an image or image sequence from the USD.

Rendering uses the same USD interface (Hydra) as is used to render the Solaris viewport, but instead of displaying the generated pixel buffers, the renderer saves them to image files. You can choose to render using any Hydra client registered with USD.

Configuration

Traditionally in Houdini, the renderer was configured using parameters on the render node. In USD, however, render settings are stored in a RenderSettings primitive in the scene tree.

See the help for the Render Settings LOP, Render Product LOP, and Render Var LOP for more information about creating USD render settings.

The parameters on this node primarily deal with launching the render process, with just a few options to override key options for controlling the render.

Available renderers

  • The list of renderers is filtered based on the data returned by the usdrenderers.py script. The husk utility, and by extension the USD Render node, only support renderers that can generate AOV buffers (that is, renderers whose aovsupport attribute is True).

  • To render to other delegates, such as Houdini GL and Storm, that do not support AOV generation, use the OpenGL ROP (this basically updates the viewport and takes a snapshot of its contents).

Tip

You need to make sure the render delegate is found by the USD plug-in search, using the PXR_PLUGINPATH_NAME environment variable.

You can also set the environment variable TF_DEBUG to PLUG_*, which causes the USD library to print out useful information as it scans for and loads plug-ins.

Parameters

Save to Disk

Click to render out the image(s).

Controls

Click to open a dialog that lets you launch a "one-off" render with different frame range and dependency settings.

Valid Frame Range

Render Current Frame

Render the current frame number (in the playbar).

Render Frame Range

Render each frame in the range set by the Start/End/Inc parameters below.

Render Frame Range (Strict)

The "Render Frame Range" option may generate frames outside the given range if they're requested by a render dependency. If you choose this option, this node will never render frames outside the given range.

Render Frame Range From Stage

Examines the USD stage of the source LOP node for a start and end timecode value. These are used as the start and end of the frame range to render. If the stage does not have this metadata set, executing a render operation will result in an error.

Start/End/Inc

When Valid frame range is "Render frame range" or "Render frame range (strict)", the start and end frames (inclusive) and interval.

Preroll/Postroll/Inc

When Valid frame range is "Render stage’s frame range", the number of frames before and after the stage’s official start and end frame to save, and the interval between time samples.

Render All Frames With a Single Process

Render all frames in a background process. Default is off. This allows continued interaction with Houdini while the render process runs.

To render multiple frames, the render process renders an image then advances the time on the scene and renders the next image (just like how the Solaris viewport plays back animation). If there is a lot of data shared between frames, this can render significantly faster compared to rendering a single frame per process.

Render with Take

Render with the parameter values stored in this take.

LOP Path

Render the USD stage output by this node.

Renderer

The Hydra client to use to render the images. The default is Karma. Alternate Hydra clients must be registered with Houdini’s USD libraries. See how the node gets the list of available renderers above.

Render Settings

Scene graph path to the RenderSettings prim to render with. (If this is blank, the node looks for default render settings on the root prim. If the root prim has no render settings, the node will use default settings.)

Override Output Image

If this is not blank, render to this file path instead of the output specified in the RenderSettings.

Resolver Context Asset Path

This file path is passed to the render command line as the resolver-context option. This argument is used to create an asset resolver context that helps the asset resolver find files while composing the USD stage. The default of this parameter is an expression that returns the corresponding parameter on the LOP Network that contains the selected LOP path

Render Command

The executable to launch to render the generated USD. The default is husk (the husk command line render utility), which does the work to feed the USD data through the Hydra interface to the renderer. You can add command line arguments to this string.

Snapshot interval

When this is on, the renderer writes out a snapshot file and partial image at every interval of this many seconds.

Verbosity

How much information to print out while rendering. Normally you should avoid "Full with VEX profiling" (slow) or "Full with VEX Profiling and NaN checks" (very slow), though they may be useful for debugging.

Block Until Render Completes

Causes Houdini to freeze after starting the render process, and only resume when the renderer exits. (This is included mostly for parameter parity with the old Mantra render nodes. It may be useful to implement a crude form of dependency ordering when batch rendering.)

Context Options

Number of Options

Lets you specify context options that only apply while rendering from this node. Set the number of context options to define/override, or use the plus and minus buttons to add or remove options.

You could have two separate render nodes with different context options, so they would write out different USD from the same LOP network depending on uses of @contextoption references in expressions. This could be useful for wedging, or to cause the LOP network to configure the stage in ways that are not good for interactively, but useful for rendering.

Option Name

For each option, the name of the option. You can reference this option in an expression using @name.

Option Type

For each option, the type of data stored in the option, either a floating point number of a string.

Option Value

For each option, the value of the option (while this node writes out USD).

Pre-Render Script

This command is run once, before any files are generated.

Pre-Frame Script

This command is run before each frame is generated.

Post-Frame Script

This command is run after each frame is generated.

Post-Render Script

This command is run once, after all files have been generated.

Strip Layers Above Layer Breaks

Enable this option to prevent layers authored above Layer Break nodes from being written to disk by this ROP. This allows a Layer Break node to dictate which portions of the LOP Network are to be saved. Disabling this option allows this behavior to be overridden, forcing the full stage authored by the LOP network to be written to disk. This may be used for debugging purposes, or to write a complete scene to disk for rendering.

Initialize Simulation OPs

Initialize DOP simulations before rendering.

Create Intermediate Directories

Create intermediate parent directories for output files as needed, such as for generated images.

Alfred Style Progress

Print percentage complete value as files are written. This is in the style expected by Pixar’s Alfred render queue.

Report Network Use

Print the number of bytes sent or received by the distributed simulation nodes during cooks triggered by this node.

This does not track network usage from, for example, saving a file to an NFS mount. It only tracks the network communication of distributed Houdini nodes.

Render nodes

  • Agent

    This output operator is used to write agent definition files.

  • Alembic

  • 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.

  • Brick Map Generator

    Allows you to convert Houdini volume primitives into Pixar brickmap files.

  • Channel

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

  • Composite

    The Composite output operator renders the image(s) produced in the Compositing Editor.

  • DSM Merge

    Merges two or more deep shadow/camera map files.

  • 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.

  • Geometry

    Generates geometry 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 the USD scene using Houdini’s Karma renderer (Beta).

  • 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.

  • Render nodes

    Render nodes either render the scene or set up render dependency networks.

  • 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

  • glTF