Houdini 19.0 Nodes LOP nodes

Karma Render Properties

Configure Render Properties for Karma.

Since 18.0

The Karma Render Properties LOP creates render vars, a render product and a render settings primitive, configured for Karma.

Parameters

Rendersettings Primitive Path

This node creates a RenderSettings prim with the configuration you set up using the parameters. This is the scene tree path where this node will create the RenderSettings prim.

Output Picture

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.

Camera

Path to a USD camera (UsdGeomCamera) prim to render the scene from.

Resolution

The horizontal and vertical size of the output image, in pixels.

Simplified Shading

Disable all shading and lighting (render with one headlight on the camera). This might be useful for preview purposes if a shaded view is too slow to render.

Rendering

Sampling

Lights and Indirect Rays

Min Ray Samples

Max Ray Samples

Volume and Opacity

Limits

Camera Effects

Motion Blur

Per-object Motion Blur

Whether motion blur should be on or off for objects that don’t explicitly have an opinion. If this is On by default, the parameters below let you set the defaults.

Geometry and Shading

Caustics

Shading
Dicing

Image Output

AOVs (Render Vars)

In USD, a RenderVar prim (for example, /Render/Products/Vars/diffuse) configures an AOV (arbitrary output variable) to generate during rendering. AOVs are extra “channels” of per-pixel data you can add to the image output (for image formats that support multiple channels per pixel, such as .exr).

By default, this node generates beauty, diffuse, glossy reflection, volume, depth, UV and normal AOVs.

The checkboxes in this section represent commonly used AOVs. You can also create custom AOVs (in the Extra Render Vars section) from light path expressions, Material outputs, geometry primvars, and other sources.

Import Render Vars from Second Input

Finds RenderVar prims in this node’s second input and adds them to this stage, so they add to the list of render vars to generate. This allows other LOP nodes (such as Background Plate) to “offer” render vars related to that node to be generated.

Import Render Products from Second Input

Finds RenderProduct prims in this node’s second input and adds them to this stage, so they add to the list of products to generate. This allows other LOP nodes to “offer” products related to that node to be generated.

The following checkbox is available next to each common render var:

Split Per LPE Tag

When this is on, the renderer creates additional AOVs specific to each tagged light. To manage LPE Tags for lights, use the LPE Tag LOP.

Component Level Output

LPE Tag AOV Limit

When splitting AOVs per lights' LPE Tag, specify the maximum number of LPE Tag AOVs beyond which the node will emit a warning.

Omit LPE Tags

When splitting AOVs per lights' LPE Tag, specify a space separated list of lights' LPE Tags which will not create new AOVs.

Beauty

Beauty

Add the beauty output as a color4f render var named C.

Beauty Unshadowed

Add the unoccluded (unshadowed) beauty output as a color3f render var named beautyunshadowed, using the LPE unoccluded;C.*.

Diffuse

Combined Diffuse

Add the combined (any number of bounces) diffuse surface reflection component as a color3f render var named combineddiffuse, using the LPE C<RD>.*L.

Direct Diffuse

Add the direct (no bounces) diffuse surface reflection component as a color3f render var named directdiffuse, using the LPE C<RD>L.

Indirect Diffuse

Add the indirect (one or more bounces) diffuse surface reflection component as a color3f render var named indirectdiffuse, using the LPE C<RD>.+L.

Combined Diffuse Unshadowed

Add the combined (any number of bounces) unoccluded diffuse surface reflection component as a color3f render var named combineddiffuseunshadowed, using the LPE unoccluded;C<RD>.*.

Direct Diffuse Unshadowed

Add the direct (no bounces) unoccluded diffuse surface reflection component as a color3f render var named directdiffuseunshadowed, using the LPE unoccluded;C<RD>L.

Indirect Diffuse Unshadowed

Add the indirect (one or more bounces) unoccluded diffuse surface reflection component as a color3f render var named indirectdiffuseunshadowed, using the LPE unoccluded;C<RD>.+L.

Reflections and Refractions

Combined Glossy Reflection

Add the combined (any number of bounces) glossy surface reflection component as a color3f render var named combinedglossyreflection, using the LPE C<RG>.*.

Direct Glossy Reflection

Add the direct (no bounces) glossy surface reflection component as a color3f render var named directglossyreflection, using the LPE C<RG>L.

Indirect Glossy Reflection

Add the indirect (one or more bounces) glossy reflection component as a color3f render var named indirectglossyreflection, using the LPE C<RG>.+L.

Glossy Transmission

Add the glossy transmission component as a color3f render var named glossytransmission, using the LPE C<TG>.*.

BSDF Labelled coat

Add the coat component as a color3f render var named coat, using the LPE C<...'coat'>.*.

Lights and Emission

Combined Emission

Add the combined (any number of bounces) emission component as a color3f render var named combinedemission, using the LPE C.*O.

Direct Emission

Add the direct (no bounces) emission component as a color3f render var named directemission, using the LPE CO.

Indirect Emission

Add the indirect (one or more bounces) emission component as a color3f render var named indirectemission, using the LPE C.+O.

Visible Lights

Add the visible lights component as a color3f render var named visiblelights, using the LPE CL.

Volume

Combined Volume

Add the combined (any number of bounces) volume component as a color3f render var named combinedvolume, using the LPE CV.*L.

Direct Volume

Add the direct (no bounces) volume component as a color3f render var named directvolume, using the LPE CVL.

Indirect Volume

Add the indirect (one or more bounces) volume component as a color3f render var named indirectvolume, using the LPE CV.+L.

SSS

BSDF Labelled sss

Add the sss component as a color3f render var named sss, using the LPE C<...'sss'>.*.

Albedo

Albedo

Add the albedo output as a color3f render var named export_basecolor. Only available with shaders that export this information, such as the principled shader.

Ray Level Output

Ray Origin (P)

Add the ray origin as a point3f render var named rayorigin.

Ray Direction (D)

Add the ray direction as a vector3f render var named raydirection.

Time (Shutter Time)

Add the shutter time as a float render var named time.

Near (Near Bias)

Add the near bias as a float render var named near.

Far (Max Distance)

Add the max distance as a float render var named far.

Mask (Intersection Mask)

Add the mask (alpha) as a float render var named mask.

Contribution

Add the ray contribution as a float render var named contribution.

P (World Space)

Add the world space position as a point3f render var named P.

Depth (Camera Space)

Add the depth as a float render var named depth.

Hitstack

Add the ray hit stack as a float render var named hitstack.

Element (Raw ID)

Add the element ID as a float render var named element.

Prim ID

Add the primitive identifier as a float render var named primid.

UV

Add the primitive hit UV as a float3 render var named UV.

Hit Dist

Add the primitive hit distance as a float render var named hitdist.

dPdz

Add the dPdz (Z-depth delta for the current microvolume) as a float render var named dPdz.

N (Smooth Normal)

Add the primitive hit normal as a normal3f render var named N.

Ng (Geometric Normal)

Add the primitive geometric normal as a normal3f render var named Ng.

Flags

Add the ray flags as a float render var named flags.

Extra Render Vars

Render Vars

Use this multiparm to add custom AOVs (render vars) to the image output.

Filters

Image Filters

Denoiser

Choose a denoiser to run on the finished image output, or No Denoiser. This utility currently supports Intel Open Image Denoise (included with Houdini) and the NVIDIA OptiX Denoiser (must be installed separately). You must be on a supported platform and have the chosen denoising library installed for this to work.

The NVIDIA OptiX Denoiser only works with NVIDIA cards. It is now included with the NVIDIA driver (version 435 or later).

Use Albedo

Some denoising libraries can use albedo to get a better sense of the image, guiding how and where it reduces noise.

Use N Input

Some denoising libraries can use normals to get a better sense of the image, guiding how and where it reduces noise.

Use Gl Input

???

AOVS

Space-separated list of AOVs to run the denoiser on.

OCIO

OCIO image filters can be added to various render vars/image planes.

Enable

Enables the OCIO image filter defined below.

Planes

The render var names to which the OCIO image filter will be applied.

Output Space

Specify the OCIO color output space the image filter will apply.

Input Space

In most cases this should be left at data. There may be some strange case where the source of the AOV is already in a defined color space, in which case you can specify the source space here.

Looks

Space-separated list of looks to apply to the finished image. A “look” is a named OCIO color transform, usually intended to achieve an artistic effect. See the OCIO documentation for more information.

Sample Filters

Color Limits

A color limit clamps the value a shading sample is allowed to contribute to an LPE image plane, to reduce appearance of “fireflies” caused by undersampling of extremely bright light sources. This multiparm lets you apply separate limits to different sets of render vars.

Enable

Enables the color limit sample filter defined below.

Planes

A space-separated list of AOV names to which this color limit will be applied.

Limit

The maximum value a shading sample is allowed to contribute to these AOVs.

Aspect Ratio

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.

Meta Data

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).

EXR Compression

The type of compression to apply to .exr output files.

Deep Output

Deep Camera Map

Generate a deep camera map image recording depth

Deep camera maps are rendered images, where semi-transparent areas (such as volumes) between the camera and the nearest opaque surface are stored with depth information. Each pixel in the image is represented as a curve describing how the transparency value changes across the depth of the scene. This allows you to composite rendered images and have the semi-transparent areas blend correctly according to their depth.

DCM Filename

The filename to save the deep camera map image to (this should be an .exr file).

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.

DCM Render Vars

Space separated list of RenderVar prim paths (not a list of AOV names). These must be the fully qualified path to the RenderVar prim and the render var name. You can use patterns to match multiple prims. The default is /Render/Products/Vars/*, which matches all prims in the branch where Houdini usually creates RenderVar prims.

Advanced

Sampling

Noise Level

Pixel Oracle

Minimum Samples

When The minimum number of samples.

Plane

The AOV to use to measure variance.

Variance Threshold

The amount of variance that triggers more rays.

Random Seed

Variance sampling involves some randomness. You can change this number to get slightly different results.

OCIO Transform

Whether to apply an OCIO transform to the pixels before measuring variance.

Disabled

Do not apply an OCIO transform.

Display View

Transform to the color space of a display.

Explicit

Transform to a named color space.

Display

When OCIO Transform is Display View, the display to transform to before measuring variance.

View

When OCIO Transform is Display View, the view to transform to before measuring variance.

Color Space

When OCIO Transform is Explicit, the color space to transform to before measuring variance.

Checkpointing

Output Checkpoint Files

When this is on, Karma will periodocially write out image tile data to a checkpoint file. If the process is terminated before completing the render, you can resume it by turning on Resume from Checkpoint and restarting.

Checkpoint File

When Output checkpoint files is on, the name of the checkpoint file to write to. The default ($HIP/render/$HIPNAME.$OS.$F4.checkpoint) puts the checkpoint file inside a render directory next to the current scene file, and includes the base name of the current scene file ($HIPNAME), this node’s name ($OS), and the render frame ($F) in the filename to help avoid two processes trying to use the same checkpoint file at the same time.

Save Frequency

When Output checkpoint files is on, Karma waits this number of seconds between writing out a checkpoint file. The default is 60.

Resume From Checkpoint

If this is on and you start a render and the renderer notices there is a valid checkpoint file, it will try to resume rendering from that checkpoint. If you want to restart the render from the beginning, you can turn this off or just delete the checkpoint file(s).

Tiles and Caching

Driver

Cancel Render if Missing Texture is Discovered

Component Labels

See also

LOP nodes

  • Add Variant

    Adds one or more variants to a variant set on a primitive. This node creates the primitive if it doesn’t exist.

  • Additional Render Vars

    Create multiple render vars.

  • Asset Reference

    Reference, Transform, and select variants of a USD Asset.

  • Assign Material

    Assigns a material to one or more USD primitives. You can use also programmatically assign materials using VEX, programmatically override material settings for each assignment, and programmatically assign materials to geometry subsets.

  • Attribute VOP

    Create/edit USD attribute values using a VOP network.

  • Attribute Wrangle

    Create/edit USD primitive attributes using a VEX snippet.

  • Auto Select LOD

    Automatically selects a level-of-detail variant based on the primitive’s distance from the camera.

  • Background Plate

    Sets up hold-out or matte objects that leave holes in the scene through which the background is visible. These prims still take shadows and contribute to reflections as if they were the background.

  • Bake Skinning

    Bakes animation driven by a UsdSkel into transforms and point positions.

  • Basis Curves

    Creates or edits a basis curves shape primitive.

  • Begin Context Options Block

    This node begins a block of LOP nodes, within which certain context options have certain values.

  • Blend

    Partially applies edits to a layer’s attributes based on a fractional weight.

  • Blend Constraint

    Blends transforms according to a list of weights specified as parameters.

  • Cache

    Caches the results of cooking the network at different times, increasing playback speed.

  • Camera

    Adds a USD camera to the scene.

  • Capsule

    Creates or edits a capsule (tube with hemispherical ends) shape primitive.

  • Collection

    Creates/edits collections using primitive patterns.

  • Component Geometry

    Geometry container or import source, in a network created by the Component Builder tool.

  • Component Geometry Variants

    Sets up geometry variants, in a network created by the Component Builder tool.

  • Component Material

    Assigns materials to geometry in a network created by the Component Builder tool.

  • Component Output

    Assembles the final Component prim, in a network created by the Component Builder tool.

  • Cone

    Creates or edits a cone shape primitive.

  • Configure Layer

    Edits metadata on a layer.

  • Configure Primitives

    Edits various metadata on one or more primitives.

  • Configure Properties

    Configures metadata on properties (relationships and attributes).

  • Configure Stage

    Configures metadata for how to load layers into the stage and asset resolution.

  • Copy Property

    Copy properties from one primitive to another, or renames properties on a primitive.

  • Create LOD

    Uses the PolyReduce SOP to automatically generate multiple levels of detail from a high-res model, and stores them as USD variants.

  • Cube

    Creates or edits a cube shape primitive.

  • Cylinder

    Creates or edits a cylinder shape primitive.

  • Distant Light

    Creates or edits a USD Distant Light, representing a far-off light source such as the sun. Adds some useful Karma-specific attributes.

  • Dome Light

    Creates or edits a USD Dome Light prim. A dome light emits light inward, simulating light coming from the sky/environment surrounding the scene.

  • Drop

    Runs a simulation to drop primitives under gravity.

  • Duplicate

    Creates copies of a prim (and its descendants).

  • Edit

    Interactively transforms prims in the viewer. Can use physics collisions to position props realistically.

  • Edit Context Options

  • Edit Material

    Allows you to edit an existing USD material by modifying parameters and shader connections. This can be useful if the existing material is on a non-editable layer.

  • Edit Material Properties

    Lets you build a spare parameter interface that reflects material or shader input attributes to directly edit their values.

  • Edit Properties

    Lets you build a spare parameter interface to directly edit attribute and relationship values.

  • Edit Prototype

    Switch point instances or USD instanceable prims to instance a different prototype.

  • Edit Target Layer

    Allows you to apply edits directly in a lower layer, instead of overriding prims and attributes in the active layer.

  • Error

    Generates a message, warning, or error, which can show up on a parent asset.

  • Explore Variants

    Visualize, set, or extract variants on primitives.

  • Extract Instances

    Converts (heroes) an instance into a real editable prim.

  • Fetch

    Grabs the output of another LOP, potentially in another LOP network.

  • Follow Path Constraint

    Constrains a prim to follow a path curve.

  • For Each

    The end node of a For-Each loop block.

  • Geometry Sequence

    Imports a sequence of geometry files into LOPs as animated geometry.

  • Geometry Subset VOP

    Creates USD geometry subsets within geometry prims (similar to groups in SOPs) based on evaluating a VEXpression or VOP network.

  • Graft Branches

    Takes prims/branches from the second input and attaches them onto branches of the scene graph tree in the first input.

  • Graft Stages

    Takes scene graph trees from other inputs and attaches them onto branches of the scene graph tree in the first input.

  • HDA Dynamic Payload

    Cooks a OBJ or SOP asset on disk and imports the animated geometry output as a USD payload.

  • Hermite Curves

    Creates or edits a hermite curves shape primitive.

  • Inline USD

    Parses usda code representing a layer and adds it to the layer stack.

  • Insertion Point

    Represents a point in the node graph where nodes can be inserted.

  • Instancer

    Instances or copies primitives onto points.

  • Instancer

    Creates a constant volume within a box.

  • Instancer

    Create multiple render products sharing common settings.

  • Karma

    Renders the USD scene using Houdini’s Karma renderer.

  • Karma Procedural

    Sets up render-time instantiation for Karma.

  • Karma Render Properties

    Configure Render Properties for Karma.

  • Karma Standard Render Vars

    Create standard karma render vars (AOVs/Image Planes).

  • LOP nodes

    LOP nodes generate USD describing characters, props, lighting, and rendering.

  • LPE Tag

    Manage Lights LPE Tags.

  • Labs RizomUV Optimize

  • Labs RizomUV Rectangularize

  • Labs RizomUV Unwrap

  • Layer Break

    Starts a new active sublayer that subsequent nodes will edit, and indicates all previous layers will be discarded when saving to disk.

  • Layer Replace

    Replaces all uses of a certain layer with a substitute layer from its second input.

  • Layout

    Provides tools for populating a scene with instanced USD assets. You can place individual components, paint/scatter components in different ways using customizable brushes, and edit existing instances.

  • Light

    Creates or edits a USD Light prim. This node also adds some useful Karma-specific attributes.

  • Light Linker

    Creates USD light link properties based on rules.

  • Light Mixer

    Lets you interactively edit USD properties for multiple lights.

  • Load Layer for Editing

  • Loft Payload Info

    Adds basic information from inside a payload to the primitive that loads the payload.

  • Look At Constraint

    Constrains a prim to always point toward a target.

  • Mask from Bounds

    Sets a primvar based on whether/by how much selected prims are inside a bounding shape.

  • Material Library

    Authors USD material primitives from shader VOP nodes.

  • Material Linker

    Creates material assignments based on rules.

  • Material Variation

    Creates attributes/primvars to override material parameters per-prim/instance.

  • Merge LOP

    Merges the layers from incoming stages into a unified layer stack.

  • Mesh

    Creates or edits a mesh shape primitive.

  • Modify Paths

    Modify asset path attribute values.

  • Modify Point Instances

    Modifies point transforms and property values for individual point instances.

  • Null

    This node does nothing. It can be useful to insert a Null into a network as a fixed point in the network that you can refer to by name in expressions/scripts.

  • Output

    Represents the output of a subnetwork. Allows you to design a node asset with multiple outputs.

  • Parent Constraint

    Makes a primitive appear to inherit the transform hierarchy of another prim somewhere else in the tree.

  • Points

    Creates or edits a Points shape primitive.

  • Points Constraint

    Position and Orient primitives using point positions from a geometry.

  • Primitive

    Bulk-creates one or more attributes of a certain type.

  • Prune

    Hides or deactivates primitives and point instances.

  • Python Script

    Lets you write Python code in the node to use the USD API to directly manipulate the stage.

  • RBD Destruction

    An example of how to a fracturing simulation in USD, also useful as a canned effect.

  • Reference

    References the contents of an external USD file into a branch of the existing scene graph tree, or removes/replaces existing references.

  • Render Geometry Settings

    Applies renderer-specific geometry settings to geometry in the scene graph.

  • Render Product

    Creates or edits a UsdRenderProduct prim, which represents an output of a renderer (such as a rendered image file or other file-like artifact produced by a renderer), with attributes configuring how to generate the product.

  • Render Settings

    Creates or edits a UsdRenderSettings prim, which holds the general settings for rendering the scene.

  • Render Var

    Specifies a custom variable computed by the renderer and/or shaders, either a shader output or a light path expression (LPE).

  • Resample Transforms

    Generates interpolated transform time samples from existing time samples on USD prims.

  • Restructure Scene Graph

    This node has various operations for editing prim paths, variant sets, and composition arcs.

  • Retime Instances

    Offsets and/or scales the timing of animation on selected instances.

  • SOP Character Import

    Imports a character or animation from a SOP network into the USD scene graph.

  • SOP Create

    Lets you create geometry in a SOP subnetwork inside this node, so you can create geometry in-place in the LOP network instead of needing a separate SOP network.

  • SOP Crowd Import

    Imports a crowd from a SOP network into the USD scene graph.

  • SOP Import

    Imports geometry from a SOP network into the USD scene graph.

  • SOP Modify

    Converts USD geometry into SOP geometry, runs the SOP subnet inside this node on the geometry, and converts the changes back to USD overrides.

  • Scene Import

    Imports models, materials, and lights from the Object level into the LOP network.

  • Scope

    Creates a scope primitive. Scope is the simplest form of grouping, and does not have a transform. Scopes can be useful for organizing the scene tree.

  • Set Extents

    Sets the bounding box metadata of selected primitives.

  • Set Variant

    Selects (switches to) one of the variants stored in a variant set on a primitive.

  • Simulation Proxy

    Generates low-poly collison geometry suitable for physical simulation and creates a proxy relationship to the original model.

  • Sphere

    Creates or edits a sphere shape primitive.

  • Split Point Instancers

    Splits a point instancer into two or more instances, which divide up the original instances.

  • Split Primitive

    Splits USD geometry prims into child primitives based on geometry subsets or primvar values.

  • Stage Manager

    Provides a convenient interface to reference in many files at once and place them in the scene graph tree.

  • Store Parameter Values

    Lets you store temporary (unsaved) data in the stage.

  • Sublayer

    Imports from USD files or other LOP node chains into as sublayers, or removes/replaces/reorders existing sublayers.

  • Subnet

    Encapsulates a LOP subnetwork, allowing you to organize and hide parts of the network.

  • Surface Constraint

    Constrain a prim to stick to a surface.

  • Switch

    Passes through one of several inputs, based on a parameter choice or expression.

  • TimeShift

    Outputs the stage as it is at a different point in the timeline.

  • Transform

    Edits the transforms of selected USD primitives.

  • Transform UV

    Moves, rotates, and scales texture coordinates on USD primitives.

  • USD ROP

  • USD Render ROP

  • Unassign Material

    Unbinds a material from one or more USD primitives.

  • Value Clip

  • Vary Material Assignment

    Assign different materials across a number of prims to create variation.

  • Volume

    References volume data on disk into a volume prim containing field prims.

  • Xform

    Creates or edits an Xform prim. Xform (and its sub-classes) represents a transform in the scene tree.