Height to Caustics Copernicus node

Creates caustic patterns on the ground from a refractive height layer.

On this page	Parameters Height Ground Quality Dispersion Inputs Outputs
Since	22.0

This node treats the height input as the surface of a refractive medium. For each pixel, it traces light from a directional or point light source through the surface, refracts the ray using the surface normal, and accumulates where the ray reaches the ground. Concentrated ray hits create brighter caustic patterns.

If a ground input is wired, the node ray-traces against that ground height layer. Otherwise, it uses a flat ground plane controlled by the Ground Center parameter.

Parameters ¶

Signature

The output layer type to generate.

RGB enables the Dispersion parameters.

See Signatures for more information.

Space

Local

Use the height layer’s local space for the light direction or position.

World

Use world space for the light direction or position.

Enable Tile

Wrap ray hit positions back into the output image when they land outside the image bounds.

Directional

Use a directional light. When this is off, the node uses a point light.

Light Azimuth

The horizontal angle of the directional light.

Light Altitude

The vertical angle of the directional light above the horizon.

Light Position

The position of the point light in the selected space.

Exposure

Multiplies the final caustic intensity.

Height ¶

Index of Refraction

The index of refraction of the medium. The default value of 1.33 approximates water.

Height Offset

The value to add to the input height before tracing rays.

Height Scale

The value to multiply the input height by before tracing rays.

Compute Derivative outside Image

Allows the internal derivative calculation for the height surface to read outside the image bounds. This affects the surface normals used for refraction.

Kernel Size

The kernel size for the internal derivative calculation on the height surface.

Ground ¶

These parameters control the wired ground layer. If no ground input is wired, the node uses Ground Center as a flat ground plane.

Ground Center

The base height of the ground. When no ground input is wired, this is the height of the flat ground plane.

Ground Offset

The value to multiply the wired ground height by before adding Ground Center.

Ray Trace Iterations

The number of Newton iterations used to approximate where refracted rays intersect the ground height layer.

Compute Derivative outside Image

Allows the internal derivative calculation for the ground layer to read outside the image bounds. This affects the ray-ground intersection solve.

Kernel Size

The kernel size for the internal derivative calculation on the ground layer.

Quality ¶

Photon Jitter Radius

The radius used to jitter photon samples during accumulation. Larger values create softer caustics with fewer grid artifacts. This has no effect when Photon Iterations is 1.

Photon Iterations

The number of photon accumulation passes to run for each pixel. Higher values reduce noise and improve denoising quality, but take longer to cook.

Denoise Iterations

The number of denoising iterations to apply after photon accumulation.

Denoise Mask

Controls where denoising is applied based on the caustic intensity mask. Higher ramp values apply stronger denoising in the corresponding intensity range.

Dispersion ¶

Dispersion parameters are available when Signature is RGB.

Method

Perturbation

Uses a fast approximation that perturbs the refractive result into color bands. This is faster than Spectrum, but is less physically accurate.

Spectrum

Samples wavelengths using the selected material’s dispersion model. This can create more vivid dispersion, but is slower.

Material

The transparent material used for spectral dispersion. This is available when Method is Spectrum.

Water

Uses water-like dispersion.

Glass

Uses glass-like dispersion, which is stronger than water.

Diamond

Uses diamond-like dispersion, which produces the strongest color separation.

Background Color

The background color composited behind the RGB caustics.

Strength

The amount of color dispersion. Higher values increase the separation between wavelengths.

Number of Colors

When Method is Perturbation, this controls the number of color bands used for photon distribution.

When Method is Spectrum, this controls the number of wavelength samples per photon iteration. Higher values create smoother spectral dispersion, but take longer to cook.

Inputs ¶

height

The height layer representing the refractive surface of the transparent medium.

ground

An optional height layer representing the ground that receives the caustics. If this input is not wired, the node uses a flat ground plane.

Outputs ¶

caustics

The generated caustic pattern on the ground.