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Since | 18.0 |
Overview ¶
-
A RenderProduct combines one or more RenderVars into a file (or interactive buffer).
-
A render product prim (
UsdRenderProduct
) is referenced by a render settings prim (UsdRenderSettings
). The render settings prim holds the general configuration for rendering the scene. The render product prim may override any of the attributes on the settings prim for this particular product. -
Specific renderers may support additional settings, such as a way to configure compression settings, file type metadata, and so on. These settings would be encoded in attributes following a renderer-specific Schema API.
-
Render product prims must be somewhere under
/Render
in the scene graph tree.
Creating vs. editing prims ¶
This node belongs to a class of nodes that create or edit USD prims directly. These nodes operate in Create mode or Edit mode. This is controlled by a Create primitives checkbox or a Create/Edit popup menu. In create mode, the node creates new prims. In edit mode, the node changes the attributes on an existing prim. The Edit mode has two variations. Edit will not modify primitives which have a houdini:editable
attribute set to false
. Force edit will modify a primitive regardless of the existence or value of this attribute. This attribute can be set on a primitive using the Configure Primitives LOP.
Parameters that correspond to a USD attribute have a pop-up menu to the left that controls how the node authors the attribute.
In addition to that, any connectable USD attributes (i.e., the ones in the inputs:
namespace) will have menu items that allow disconnecting them from their sources.
Pop-up menu item |
Meaning |
---|---|
Set or Create |
Sets the attribute to the given value, whether it previously existed or not. |
Set If Exists |
Only set the attribute to the given value if it previously existed. Use this mode to make sure an attribute is only set on primitives of the correct type. For example, only |
Block |
Makes the attribute appear to not exist, so it takes on its default value. (If the attribute doesn’t already exist on the prim, this does nothing.) |
Disconnect Input |
Deletes the attribute input connection to its source. Input connections take precedence over attribute values, so disconnecting an input allows the attribute value to take effect. |
Do Nothing |
Ignore this parameter, don’t create or change the attribute in any way. |
Parameters ¶
Sampling Behavior
Cooking this node can generate many USD time samples, rather than just a single time sample at the current time. This can be equivalent to having a Cache LOP following this node, but it will evaluate much faster, and does not cache data from any other nodes. This allows animated data to be authored to USD without introducing a node time dependency which would then cause all following nodes to also be time dependent. This can vastly improve playback performance of some LOP Networks.
In all sampling modes, if a parameter on this node does not vary with time, and does not rely on other time sampled data from the stage, only a single default value will be generated in USD for the corresponding attribute. USD time samples are only generated for parameters that may vary over time.
Sample Current Frame
A single time sample will be generated for the current time.
Sample Frame Range If Input Is Not Time Dependent
If the input to this node is time dependent, this node behaves as if it is in Sample current frame
mode. Otherwise it behaves as if it is in Sample frame range
mode.
Sample Frame Range
The Start/End/Inc parameter is used to generate multiple times at which this node’s parameters are evaluated, and a USD time sample is created for each attribute at each one of these times.
Start/End/Inc
When the Sampling behavior is Sample frame range
, this parameter controls the number and spacing of base time samples to be generated by this node. The default values of this parameter are @fstart
, @fend
, and @finc
. These values correspond to the start, end, and step size of the global Houdini animation settings when interacting with Houdini. When using a ROP node to generate a range of frames, these values correspond to the start, end, and increment values specified on the ROP node being executed. This default ensures that a USD file written to disk will contain time samples for exactly the frame range requested by the ROP (regardless of the Houdini animation settings).
Subframe Sampling
For each primary sample generated by this node, these parameters can cause additional samples to be generated around that primary sample time. This is most often used to ensure that accurate data exists at exactly the camera shutter open and close times, as well as at the primary sample time.
Shutter
Controls the method used to specify the shutter open and close times relative to the primary sample times.
Specify Manually
The Shutter Open/Close parameter values provide exact offset values relative to the primary sample time.
Use Camera Prim
The Camera Prim parameter provides the scene graph path of a camera primitive from which the shutter open and close times are extracted to provide the offset values relative to the primary time sample.
Shutter Open/Close
When Shutter is set to Specify Manually, these two offset values are added to the primary sample time to indicate the shutter open and close times. The open time should be less than or equal to zero, and the close time should be greater than or equal to zero.
Camera Prim
When Shutter is set to Use Camera Prim, this is the scene graph path of a camera prim on the input node’s stage. The shutter open and close attribute values are read from this primitive.
Samples
The number of subframe samples to create for each primary sample. These samples are evenly distributed between the shutter open and close times. Note that such an even distribution may or may not create a sample at exactly the primary sample time.
Always Include Frame Sample
When turned on, forces a sample to be created at exactly the primary sample time. If the Samples value, together with the shutter open and close times, already place a sample at the primary sample time, turning on this option has no effect. Otherwise, this option causes an addition sample to be added. This means that the actual number of samples per primary sample may in fact be one more than the number specified in the Samples parameter.
Action
Whether this node should create new prims, or edit existing prims. In addition, the Force Edit
option can be chosen to cause this node to ignore the houdini:editable
attribute on prims, and always edit the specified attributes. This is in contrast to the Edit
mode which will trigger a warning and not set attributes on prims with the houdini:editable
attribute set to false
.
Primitive Path
In create mode, this lets you control where in the scene graph to create the prim(s).
The default is usually /$OS
. This creates a primitive at the root level with the same name as the node (for example, /tube1
). This is a useful default for preventing naming conflicts, but terrible for organization. You should try to remember to change the Primitive path to a better value when you create prims.
For example, instead of naming models after the node that created them, you might want to name them after the geometry inside, and organize them under a /Models
branch.
The “Create primitives” section contains basic controls for how to create the new prim(s).
Primitives
In edit mode, the node has a Primitive pattern parameter. This lets you specify the prim(s) the node should operate on. You can click the select button beside the text box to select the primitives from the scene graph tree. You can also use primitive patterns for advanced matching, including matching all prims in a collection.
Initialize Parameters
Changes the state of all control menu parameters to Do Nothing
, so that this node will not apply any changes. Also grabs the current values of each property from the first Primitives match, and sets the values of the corresponding parameters to match. This means that changing any parameter’s control menu to Set or Create
mode will set the property to its current value, making it easier to apply changes to an existing value rather than setting a brand new value.
Create Primitives
This section only appears when the node is creating primitives.
For example:
-
If you want to create a new cube primitive at
/world/objects/cube1
on an empty stage: Set Primitive Specifier to “Define”, and the Parent Primitive Type to “Xform”. -
If you want to override the radius of a sphere at
/world/objects/sphere1
: Set Primitive Specifier to “Over”, and the Parent Primitive Type to None. This makes sure the primitive types of any existing ancestor prims are not be modified by this node.
Primitive Count
The number of primitives to create.
Primitive Kind
Set all created prims to have this kind.
Primitive Specifier
The USD operator to use when creating the new prims.
Define
Authors a completely new prim. Use this if you want to create a brand new prim or replace an existing prim.
Over
Authors an override of an existing prim. Attributes not explicitly authored on this prim will get their values from the existing prim on the lower layer.
Class
Define a primitive class. This is usually not necessary unless you are doing deep USD magic.
Class Ancestor
If the Specifier is Define
or Over
, this parameter will cause some ancestor primitives to be authored with a specifier of Class
. This makes it easy to create an Over
or Define
within a Class
without having to use two separate nodes. When the Specifier is Class
, this parameter is disabled because the entire primitive hierarchy is already authored as Class
primitives.
Parent Primitive Type
If any parents of a path in Primitive paths do not exist, this node will automatically create them. In this case, it will create parent nodes of this type.
Subframe Sampling
For each primary sample generated by this node, these parameters can cause additional samples to be generated around that primary sample time. This is most often used to ensure that accurate data exists at exactly the camera shutter open and close times, as well as at the primary sample time.
Shutter
Controls the method used to specify the shutter open and close times relative to the primary sample times.
Specify Manually
The Shutter Open/Close parameter values provide exact offset values relative to the primary sample time.
Use Camera Prim
The Camera Prim parameter provides the scene graph path of a camera primitive from which the shutter open and close times are extracted to provide the offset values relative to the primary time sample.
Shutter Open/Close
When Shutter is set to Specify Manually, these two offset values are added to the primary sample time to indicate the shutter open and close times. The open time should be less than or equal to zero, and the close time should be greater than or equal to zero.
Camera Prim
When Shutter is set to Use Camera Prim, this is the scene graph path of a camera prim on the input node’s stage. The shutter open and close attribute values are read from this primitive.
Samples
The number of subframe samples to create for each primary sample. These samples are evenly distributed between the shutter open and close times. Note that such an even distribution may or may not create a sample at exactly the primary sample time.
Always Include Frame Sample
When turned on, forces a sample to be created at exactly the primary sample time. If the Samples value, together with the shutter open and close times, already place a sample at the primary sample time, turning on this option has no effect. Otherwise, this option causes an addition sample to be added. This means that the actual number of samples per primary sample may in fact be one more than the number specified in the Samples parameter.
Action
Whether this node should create new prims, or edit existing prims. In addition, the Force Edit
option can be chosen to cause this node to ignore the houdini:editable
attribute on prims, and always edit the specified attributes. This is in contrast to the Edit
mode which will trigger a warning and not set attributes on prims with the houdini:editable
attribute set to false
.
Primitive Path
In create mode, this lets you control where in the scene graph to create the prim(s).
The default is usually /$OS
. This creates a primitive at the root level with the same name as the node (for example, /tube1
). This is a useful default for preventing naming conflicts, but terrible for organization. You should try to remember to change the Primitive path to a better value when you create prims.
For example, instead of naming models after the node that created them, you might want to name them after the geometry inside, and organize them under a /Models
branch.
The “Create primitives” section contains basic controls for how to create the new prim(s).
Primitives
In edit mode, the node has a Primitive pattern parameter. This lets you specify the prim(s) the node should operate on. You can click the select button beside the text box to select the primitives from the scene graph tree. You can also use primitive patterns for advanced matching, including matching all prims in a collection.
Initialize Parameters
Changes the state of all control menu parameters to Do Nothing
, so that this node will not apply any changes. Also grabs the current values of each property from the first Primitives match, and sets the values of the corresponding parameters to match. This means that changing any parameter’s control menu to Set or Create
mode will set the property to its current value, making it easier to apply changes to an existing value rather than setting a brand new value.
Create Primitives
This section only appears when the node is creating primitives.
For example:
-
If you want to create a new cube primitive at
/world/objects/cube1
on an empty stage: Set Primitive Specifier to “Define”, and the Parent Primitive Type to “Xform”. -
If you want to override the radius of a sphere at
/world/objects/sphere1
: Set Primitive Specifier to “Over”, and the Parent Primitive Type to None. This makes sure the primitive types of any existing ancestor prims are not be modified by this node.
Primitive Count
The number of primitives to create.
Primitive Kind
Set all created prims to have this kind.
Primitive Specifier
The USD operator to use when creating the new prims.
Define
Authors a completely new prim. Use this if you want to create a brand new prim or replace an existing prim.
Over
Authors an override of an existing prim. Attributes not explicitly authored on this prim will get their values from the existing prim on the lower layer.
Class
Define a primitive class. This is usually not necessary unless you are doing deep USD magic.
Class Ancestor
If the Specifier is Define
or Over
, this parameter will cause some ancestor primitives to be authored with a specifier of Class
. This makes it easy to create an Over
or Define
within a Class
without having to use two separate nodes. When the Specifier is Class
, this parameter is disabled because the entire primitive hierarchy is already authored as Class
primitives.
Parent Primitive Type
If any parents of a path in Primitive paths do not exist, this node will automatically create them. In this case, it will create parent nodes of this type.
Standard ¶
Ordered Render Vars
Specifies the RenderVars that should be consumed and combined into the final product. If ordering is relevant to the output driver, then the ordering of targets in this relationship provides the order to use. However, only explicitly named RenderVars will appear in the specified order. RenderVars specified using wildcard matching or VEX evaluation will appear in alphabetical order after any explicitly named RenderVars.
Product Name
The name of the render product. The use of this string is specific to the delegate, but it usually represents and output filename or a device name. When rendering with Karma, you can set this value to an output image filename (usually an .exr
file), or ip
which renders the image in MPlay.
Include $F
in the file name to insert the frame number. This is necessary when rendering animation. See expressions in file names for more information.
Product Type
The type of output to produce. The default, “raster”, indicates a 2D image.
In the future, UsdRender may define additional product types.
Camera
Path to a USD camera (UsdGeomCamera
) prim to render the scene from.
Resolution Mode
Use the USD Camera’s aperture aspect ratio to automatically set one dimension of the resolution.
The computed parm is set using an expression, but is locked to prevent accidental edits.
Manual
Set the resolution height and width values.
Set Width, Compute Height from Aperture
Set the width size, while height is computed from the width and the camera aspect ratio.
Set Height, Compute Width from Aperture
Set the height size, while width is computed from the width and the camera aspect ratio.
Resolution
The horizontal and vertical size of the output image, in pixels.
Disable Motion Blur
Override the camera’s Shutter close parameter to be equal to its Shutter open time, to produce a zero-width shutter interval. This is a convenient way to disable motion blur.
Aspect Ratio Conform Policy
What to do if the aspect ratio of the output image (Resolution width divided by height) doesn’t match the aspect ratio of the camera aperture (controlled by attributes on the camera). This allows a standard renderer to do something reasonable when you switch between cameras.
Expand Aperture
If necessary, expand the camera aperture to match the image.
Crop Aperture
If necessary, crop the camera aperture to match the image.
Adjust Aperture Width
If necessary, change the camera aperture width to match the image.
Adjust Aperture Height
If necessary, change the camera aperture height to match the image.
Adjust Pixel Aspect Ratio
Change the aspect ratio of the image to match the camera.
Data Window NDC
Directs the renderer to only render within this window of the entire output image. You specify the window as minX, minY, maxX, maxY
, where each number is a normalized value from 0
to 1
. 0, 0
is the bottom left, 1, 1
is the top right, 0.5, 0.5
is the center, and so on. The default is 0, 0, 1, 1
(no cropping). Note that you can use negative values. For example, -0.1, -0.1, 1.1, 1.1
will give you 10% overscan on each side.
You can use this window to temporarily crop the render to a smaller region, for testing purposes.
Pixels are only rendered if they are fully inside the window.
The normalized coordinates map to the image after any adjustments by the Aspect ratio conform policy.
Pixel Aspect Ratio
The aspect ratio (width/height) of image pixels (not the image itself).
The default is 1.0
, indicating square pixels.
Husk ¶
The husk
utility looks for properties on the RenderProduct when saving image data.
Any property that is prefixed with driver:parameters:
will be passed through to the Houdini image device library.
Each image format has a different set of tags and options which can be set using metadata. The parameter name may also be prefixed with the format identifier to send the parameter to a specific format. For example driver:parameters:OpenEXR:customMetaData
will be passed to OpenEXR, but not JPEG files.
Artist
The name of the person, department, or studio that created the image file. The node will set this field on the output image if the image format supports metadata (for example, .exr
).
Comment
An arbitrary comment, for example a description of the purpose of the output image. The node will set this field on the output image if the image format supports metadata (for example, .exr
).
Hostname
The name of the computer that generated this the output file. The node will set this field on the output image if the image format supports metadata (for example, .exr
).
Image Format
Normally, husk
will infer the image format from the file extension. You can also specify the image format by choosing a format from the associated drop-down menu.
Source Color Space
Specifies the default source color space for all color RenderVars. You can override the color space on a per-AOV basis by setting the property on a Render Var LOP.
Output Color Space
Specifies the default source color space for all color RenderVars. You can override the color space on a per-AOV basis by setting the property on a Render Var LOP. Specifying the source color space on the render product will force all AOVs to have the chosen source color space - including non-color AOVs (like point
or normal data
).
Compression
Specifies the saved image’s default file compression. Some formats allow you to specify compression per AOV and you can override this property through a Render Var LOP.
OpenEXR Compression
Sets the compression for saved OpenEXR files. When saving multi-part OpenEXR files, you can specify compression per AOV through a Render Var LOP.
DWA Compression Level
The compression level when using DWA-A or DWA-B compression.
Karma ¶
DCM Compression
Compression value between 0
and 10
. Used to limit the number of samples
which are stored in a lossy compression mode for volume samples. The
compression parameter determines the maximum possible error in scalar
channels for each sample. For compression greater than 0
, the following
relationship holds: Error = 1/(2^(10-compression))
DCM Of Size
Opacity is usually computed as a full-color value and stored as such. To
cut down on file size, if full color is not needed, this settings can be
used to store a monochromatic version of the full color value.
Set this value to 1
for monochrome, 3
for full color.
DCM Z-Bias
Used in compression to merge together samples which are closer than the given threshold. Samples that are closer together than this bias value are merged into a single sample whose z-front and z-back span encompasses all the merged samples.