Houdini 20.5 Nodes Render nodes

RenderMan render node

Renders the scene using Pixar’s RenderMan renderer.

This node type is hidden. It is no longer supported.
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This output operator is used to drive the RenderMan rendering program. The operator sets up all necessary options and then invokes the renderer. Alternatively, the output can be saved to disk as a script file to be rendered later.

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

Specific parameters other than those listed below map directly to a feature in RenderMan. Various options and attributes can be set using these parameters. If a parameter is blank, then no value will be output in the RIB (i.e. the default values from the rendermn.ini file will be used).

Note

This renderer is not available by default. Available renderers are restricted to Mantra only. You can make RenderMan available in the tab menu by adding it in the Edit ▸ Preferences ▸ Rendering menu.

Parameters

Render

Renders with the last render control settings, using the path specified in Display.

Render to MPlay

Renders with the last render control settings, redirecting rendered frames to MPlay, instead of the specified path. Note that deep images will still be written out to their specified output path, if enabled.

Render Control

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

Valid Frame Range

Render Current Frame

Renders 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

Renders 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)

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

Start/End/Inc

Specifies the range of frames to render (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 rendered (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 to restore the current take when rendering has been completed.

Main

The output driver is responsible for generating RIB files. These files describe the Houdini scene to RenderMan. The Main tab determines how the RIB generation is processed.

Render Target

Chooses a target version of RenderMan allows you to generate a RIB targeted to a specific build of RenderMan.

RIB Backend

Chooses how to drive PRMan to render the scene.

SOHO

Uses SOHO, Houdini’s customizable Python scripted output system, to generate a RIB stream.

PRMan for Python

Use PRMan’s Python API to render directly. This has advantages and disadvantages over SOHO.

  • It’s probably faster than using SOHO, because it doesn’t have the overhead of writing the RIB to a file or pipe.

  • PRMan runs in the same process as Houdini, so if PRMan crashes, Houdini may crash.

  • Data structures in Python need to be massaged to fit properly with PRMan for Python, so it may use more memory.

Generate Python

Generates a Python script that uses PRMan’s Python API to render the scene.

Camera

The camera object which defines the scene.

RiBegin

The string Houdini passes to RiBegin() when RIB Backend is PRMan or Python. See the documentation for PRMan for Python for more information. The default is __render, which creates a rendering context.

Disk File

The location where the RIB file is saved to disk. You must turn on the Disk File checkbox to enable this parameter.

Command

The command where the RIB file is sent. This will be disabled if the RIB file is saved to disk.

Wait for Render to Complete

When sending the output to a command, Houdini will normally return control after it is finished writing the RIB. This allows the render process to complete in the background. Turning on this parameter will force Houdini to block until the output driver finishes rendering the frame.

When rendering a frame range, this option is automatically turned on. However, the option is not automatically turned on when rendering in an hscript or python loop construct. Therefore caution must be used or it is possible to end up starting multiple background renders.

Note

The rps and rkill hscript commands can be used to query or kill background renders.

See the Troubleshooting section 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.

Skip Existing Frames

Skip rendering of existing frames. There are three values for this parameter.

Overwrite existing frames

This option will render every frame, regardless whether there’s a file on disk or not.

Skip frames that exist

If there’s a disk file that matches the vm_picture parameter, no render will be performed.

Skip frames that are valid images

If a disk file exists, the integrity of the image is checked before rendering is performed. This option incurs the cost of reading the image, but will re-render images that weren’t fully rendered.

Initialize Simulation OPs

If this option is turned on, all POP and DOP simulations will be put in a reset state before rendering.

Objects

The parameters on this tab determine which objects and lights are included in the RIB.

Candidate Objects

The geometry objects in this parameter will be included in the RIB if their display flags are turned on and their display channel is enabled.

Force Objects

Objects in this parameter are added to the RIB regardless of the state of their display. Objects can only be added to the RIB once.

Exclude Objects

Objects in this parameter are excluded from the scene, regardless of whether they are selected in the Candidate Objects or Force Objects.

Solo Light

Only lights in this parameter will be included in the RIB. This includes shadow map generation and illumination. If this parameter is set, the candidate, forced, and exclusion parameters are ignored.

Note

Using this parameter in conjunction with the render_viewcamera property provides a quick way of generating shadow maps for selected lights.

Candidate Lights

Each light in this parameter is added to the RIB if the dimmer channel of the light is not 0. The standard light sets the dimmer channel to 0 when the light is not enabled.

Force Lights

The lights in this parameter are added to the RIB regardless of the value in their dimmer channels.

Exclude Lights

These lights will be excluded from the scene, even if they are selected in Candidate Lights or Force Lights__.

Visible Fog

The fog/atmosphere objects in this parameter are included in the RIB if their display flags are turned on and their display channel is enabled.

Properties

Display

Hover your mouse over the parameter names and use the reference in the tool tip to look up the corresponding information in the RenderMan documentation.

Ri AOV

Hover your mouse over the parameter names and use the reference in the tool tip to look up the corresponding information in the RenderMan documentation.

Hider

Hover your mouse over the parameter names and use the reference in the tool tip to look up the corresponding information in the RenderMan documentation.

Sampling

Hover your mouse over the parameter names and use the reference in the tool tip to look up the corresponding information in the RenderMan documentation for the Trace Motion Blur and Pixel Samples parameters.

Allow Motion Blur

RenderMan will render the image using motion blur. The shutter parameter on the camera determines the duration of the shutter, specified as a fraction of the frame.

Xform Time Samples

The number of transformation blur motion samples. Each object (unless the parameter exists on the object) will have this many transforms output over the shutter duration. Increasing this number will result in smoother sub-frame motion, at a small memory and compute expense. Any number of segments may be specified.

Geo Time Samples

The number of deformation blur motion samples. Each object (unless the parameter exists on the object) will have this many copies of the geometry included in the RIB. When an object is deforming, increasing this parameter will result in smoother sub-frame motion blur.

This option has no effect objects, which use velocity blur, since velocity blur is linear by nature.

Note

Any number of segments may be specified; however, duplicate geometry is sent down for each sample which may significantly impact the memory footprint of RenderMan.

Motion Blur Style

The type of motion blur. You can choose either a trailing, centered, or leading blur.

DOF

Enable Depth of Field

Hover your mouse over the parameter name and use the reference in the tool tip to look up the corresponding information in the RenderMan documentation.

Focus

The lens focal distance and distance from the camera at which objects will be in focus. If the f-stop channel is also used, objects outside this distance will be blurred.

F-Stop

Lens f-stop. Determines blurriness of depth-of field effects.

Render

Hover your mouse over the parameter names and use the reference in the tool tip to look up the corresponding information in the RenderMan documentation for the Global Shadow Bias, Trace Displacements, Global Trace Depth, Enable Gaussian Texture, Enable Texture Lerp, and Volume Strategy parameters.

Create Image From Viewing Camera

Renders an image from the viewing camera. Sometimes, it is useful to skip this render, for example, when rendering shadow maps.

Auto-Generate Shadow Maps

Enable or disable shadow map generation. Each light also has its own controls to determine whether shadow maps will be generated.

Auto-Generate Environment Maps

Enable or disable environment map generation. Each object can be set up to generate an environment map of all the other objects in the scene.

Attributes

Hover your mouse over the parameter names and use the reference in the tool tip to look up the corresponding information in the RenderMan documentation.

Global Illum

Hover your mouse over the parameter names and use the reference in the tool tip to look up the corresponding information in the RenderMan documentation.

Limits

Hover your mouse over the parameter names and use the reference in the tool tip to look up the corresponding information in the RenderMan documentation.

Paths

Hover your mouse over the parameter names and use the reference in the tool tip to look up the corresponding information in the RenderMan documentation.

Statistics

Hover your mouse over the parameter names and use the reference in the tool tip to look up the corresponding information in the RenderMan documentation.

Scripts

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.

Note

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 RIBs are generated. It is only run once per render.

Pre-Frame Script

This command is run before each RIB is generated.

Post-Frame Script

This command is run after each RIB is generated.

Note

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

Post-Render Script

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

Note

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

Advanced

When generating blobby primitives in RIB, the string parameters were hard-coded to an empty list. SOHO will now search for a detail attribute named RiBlobby_Strings (case sensitive). This value of this string will be parsed using the syntax described in the Python function shlex.split(). The resulting list of strings will be output in the RiBlobby() call.

Locals

N

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

NRENDER

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.

  • Flipbook

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

  • 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.

  • Image

    Writes the output of a COP network to disk.

  • 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

    Exports 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.

  • Labs ZibraVDB Compress (Alpha)

    Compresses an OpenVDB sequence and caches it to disk as a single file.

  • 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