Houdini 20.5 Nodes LOP nodes

Houdini Procedural: Ocean

Houdini Ocean Procedural for Solaris.

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Since 20.0

This node configures Houdini Ocean Procedural primitives, which provide a render-time Ocean solution that saves disk-space and avoids texture baking. The procedural takes low-resolution input geometry and generates high-resolution geometry at render time by dicing and displacing the input to the specified resolution.

This dicing and displacement was previously performed in VEX, and was therefore only available in Mantra or Karma, limiting render-time ocean displacement to those renderers, with other renderers limited to baking per-frame textures. However, because the procedural now handles the dicing and displacement aspects of the ocean rendering process, any Solaris-compatible renderer can render fully displaced oceans without per-frame texture baking.

The basis of this procedural is the Remesh to Camera SOP followed by optional foam particle splatting, then displacing the geometry with the Ocean Sample Layers VOP.

Tips

  • When using the Small Ocean or Large Ocean Ocean shelf tools inside the Solaris /stage context, the ocean proxy and render geometry will be created within the Houdini Ocean Procedural LOP itself, keeping all components within Solaris.

  • After changing the parameters on the Ocean Spectrum SOP(s) that generate the ocean spectrum, you will need to re-save the spectra to a file for the renderer to pick up the changes, then press the Reload Geometry button.

  • The Preview Quality parameter controls the resolution of the ocean when previewed in the Solaris viewport with a Preview Houdini Procedurals LOP. The Dicing Quality parameter controls the resolution for a full-quality render via husk or the USD Render ROP.

Parameters

Primitive Path

The scene graph path at which to create the ocean procedural prim.

Spectrum

Spectrum File

The location of the ocean spectrum file, containing one or more ocean spectra as created the by the Ocean Spectrum SOP.

Mask File

An optional animated file sequence of mask geometry that can be used to mask the ocean displacement, often created by the Particle Fluid Mask SOP and set up by the Ocean Flat Tank or Guided Ocean Layer shelf tools.

Time

The time at which the ocean surface should be evaluated.

Reload Geometry

Force a reload of the Spectrum File geometry, which will refresh any previews of the ocean after a change to the spectrum file on disk,

Geometry

Render Geometry

The path to the geometry that will be diced and displaced by the procedural.

Group

The primitive group on the Render Geometry that should be diced and displaced.

Reference Render Geometry as Interior

Create a second USD reference to the Render Geometry that will be rendered as the ocean interior, usually using a uniform volume material to give the appearance of depth falloff within the ocean volume.

Preview Quality

The dicing resolution for the procedural when previewing the ocean in the Solaris viewport with a Preview Houdini Procedurals LOP.

Note

The full render quality is controlled by the main Dicing Quality parameter.

Dicing

Camera LOP Path

Path to the camera primitive source LOP Node.

Camera Prinitive Path

The camera primitive used for dicing and rendering the ocean.

Dicing Quality

The dicing resolution of the procedural. A setting of 1 generally gives full resolution, but can be increased for more detail. If you only require more detail at the horizon, consider increasing Z Importance instead.

Geometry Z Measure

The space in which the diced ocean geometry’s z-coordinate should be projected before measuring if it meets the Dicing Quality criterion. The x and y coordinates are always in pixel space, but the z coordinate along the camera direction can be in a different space.

Camera Space

The z coordinate is mapped to camera space, and its value will range 0 to (camera_far - camera_near). This mapping works well for most small to medium-scale scenes, and retains good detail at the horizon. However, for very large camera distances, it can lead to excessive dicing and memory usage as the geometry becomes very stretched at the horizon.

Pixel Space

The z coordinate is mapped to pixel space, and its value will range from 0 to max(xres, yres). This mapping gives more consistent dicing across widely varying scales, but might require increasing Z Importance for long camera views to keep sufficient horizon detail.

Z Importance

A scale on the mapping specified in the Geometry Z Measure parameter. Increasing this value will increase detail at distance along the horizon, generally with lower memory usage than increasing the overall Dicing Quality.

Resolution

The resolution of the image to be rendered by the Camera.

Screen Window Size

The size of the screen window. Increasing this value will extend the subdivision to the offscreen area, which is especially useful if the resulting geometry might be displaced horizontally into view.

Downsample

Downsample the incoming ocean spectra before evaluating any ocean values. This parameter specifies the number of powers of two to remove from the resolution of the incoming ocean spectrum. For example, if the spectrum was originally specified at resolution 10 to generate a 1024 x 1024 volume, downsampling by 2 will evaluate ocean volumes at resolution 8, a 256 x 256 volume.

Anti-Alias Blur

A scale on the polygon size before measuring against wavelength for anti-aliasing. Decrease its value to reduce the amount of downsampling done, or set to zero to disable completely.

Verbose

Output statistics to the console about ocean dicing, displacement, and foam splatting.

Shading

Surface Material

The material applied to the surface render geometry. The default material is a MaterialX shader that will work with many renderers that support MaterialX.

Interior Material

The material applied to the interior ocean volume, usually rendered as a uniform volume to emulate depth falloff beneath the surface of the water. The default material will work with Karma CPU and XPU.

Proxy Material

The material used for viewport display of the ocean surface, with some features like refraction disabled.

Point Velocity

Generate a velocities primvar that can be used for shading or motion blur.

Cusp Min/Max

When enabled, the procedural will generate a cusp primvar that can be used for shading and/or displacement of the procedural surface. The Cusp Min/Max parameter remaps the specified cusp range to 0-1.

Cusp Gamma

Applies a gamma curve to the cusp value after remapping according to Cusp Min/Max.

Cusp Intensity

A multiplier applied to the cusp value after remapping and gamma scaling.

Foam Particles

An optional animated file sequence of foam particles that can be used to create a foam primvar on the ocean for shading and/or displacement of the procedural surface.

Foam Pattern

If the Foam Particles parameter is set, these parameters control generation of a foam primvar from the foam particles that can be used in shading and displacement. These foam particles are typically created using the Ocean Foam SOP.

Radius Scale

A scale on the particle radius applied before looking up foam particles around a shading point. Increase this value and decrease Alpha to smooth out the look of the foam.

Alpha

The amount of opacity each particle will contribute. Increase this value for a thicker foam layer.

Filter Width

How much to filter the streak pattern to avoid aliasing artifacts when viewed from a distance.

Foam Min/Max

When enabled, the procedural will generate a foam primvar that can be used for shading and/or displacement of the procedural surface. The Foam Min/Max parameter remaps the specified foam range to 0-1.

Foam Gamma

Applies a gamma curve to the foam value after remapping according to Foam Min/Max.

Foam Intensity

A multiplier applied to the foam value after remapping and gamma scaling.

Streaks

Direction

The direction in which to stretch the Frequency to stretch out the foam in that direction. Setting this to the prevailing wind direction or wind direction plus 90 degress can give interesting effects.

Bias

The amount of Frequency stretching to do along the streak Direction.

Sharpness

How sharp the edges of the foam are. High values will create a sharper more web-like pattern, low values will create a softer, rounder pattern.

Frequency

The frequency of the streak pattern.

Offset

How much to offset the streak pattern.

Bubbles

Frequency

The frequency of the bubble pattern.

Offset

How much to offset the bubble pattern.

Displacement

Cusp Displacement

The diced ocean surface will be displaced in the normal direction by the output cusp primvar scaled by this amount.

Foam Displacement

The diced ocean surface will be displaced in the normal direction by the output foam primvar scaled by this parameter.

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.

  • Assign Prototypes

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

  • 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.

  • Coordinate System

    Define named coordinate systems used in shaders.

  • 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.

  • Draw Mode

    Sets draw mode properties on USD model assets.

  • 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 Properties From Node

    Lets you refer to the parameter on another node to directly edit attribute and relationship values.

  • Edit Prototypes

    Modify the prototypes of native or point instances in-place, without disturbing the instancing setup.

  • 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.

  • File Cache

    Caches (writes out once and then reads from) USD layers (possibly animated) to disk.

  • Follow Path Constraint

    Constrains a prim to follow a path curve.

  • For Each

    The end node of a For-Each loop block.

  • Geometry Clip Sequence

  • Geometry Color

    Adds display color and display opacity primvars to geometry.

  • 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.

  • Houdini Feather Procedural

    Generates feathers for rendering.

  • Houdini Preview Procedurals

    Invokes Houdini Procedurals while working interactively.

  • Houdini Procedural: Crowd

    Houdini Crowd Procedural for Solaris.

  • Houdini Procedural: Hair

    Houdini Hair Procedural for Solaris.

  • Houdini Procedural: Ocean

    Houdini Ocean Procedural for Solaris.

  • Houdini Procedural: RBD

    Houdini RBD Procedural for Solaris.

  • 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.

  • Isolate Scene

    Work in masked areas of the stage.

  • Karma

    Renders the USD scene using Houdini’s Karma renderer.

  • Karma Cryptomatte

    Setup Cryptomatte AOVs for Karma.

  • Karma Fog Box

    Creates a constant volume within a box.

  • Karma Physical Sky

    Creates a Karma Sky Dome and Sun Light rig.

  • Karma Render Products

    Create multiple render products sharing common settings.

  • Karma Render Properties

    Configure Render Properties for Karma.

  • Karma Sky Atmosphere

    Creates or edits a Karma Sky Atmosphere.

  • Karma Sky Dome Light

    Creates or edits a Karma Sky Dome Light.

  • Karma Standard Render Vars

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

  • LPE Tag

    Manage Lights' LPE Tags.

  • Labs Karma AOVs for RenderMan Denoiser

    Generates AOVs for the Pixar RenderMan denoiser.

  • 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 Filter Library

    Authors USD light filter primitives from VOP nodes.

  • 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.

  • Match Size

    Resizes and recenters the input geometry to match a reference bounding box.

  • 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.

  • Merge Point Instancers

    Merges point instancers into a single consolidated point instancer.

  • 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.

  • Motion Blur

    Adds time samples to allow motion blur when rendering.

  • 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 for a fracturing simulation in USD, also useful as a canned effect.

  • Reference

    References the contents of a external USD files and/or layers created by other LOP nodes into a branch of the existing scene graph tree. Can also remove or replace 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 Doctor

    Validates primitives on a USD stage.

  • 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.

  • Split Scene

    This node splits a scene graph into two disjoint sets of primitives.

  • 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.