Houdini 20.5 Nodes Copernicus nodes

Derivative Copernicus node

Computes the derivative of the source layer along the x- and y-axis.

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This node computes the derivative of the source layer along the x- and y-axis. This derivative represents the change in pixel values along those axes. For example, this is useful for edge detection.

Parameters

Signature

The layer type that the source accepts.

See Signatures for more information.

Angle

Rotates the position at which the pixels are sampled by this angle. An angle of 90 degrees would mean that the x derivative would be equal to the y derivative of an angle 0.

Scale

Multiplies the output value by this amount.

Offset

Adds this amount to the output value.

Read Pixels outside Image

Determines if derivatives at the boundary should read outside the image or restrict to the image range. Reading outside is useful for building seamless textures with wrap-mode. But restricting to the image range avoids artificial flattening of the derivative at the boundary in clamp modes, as it acts more like an extrapolation.

Kernel Size

Usually a derivative is computed with adjacent pixels, but if the values are slowly varying there may not be enough bit-depth to get smooth derivatives. This will expand the distance (in buffer elements) to compute the derivative, possibly removing stepping artifacts from the derivative.

Inputs

source

The original layer to compute the derivatives from.

Outputs

dCdx

The derivative along the x-axis.

dCdy

The derivative along the y-axis.

Copernicus nodes