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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.
Block Until Render Completes
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.
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.
Examples
The following examples include this node.
Basic RIS Shading Example Example for RIS Shader Network shader node
| See also |
mantra output driver
