This is a simple and useful pattern for creating edge effects and curvature based results like wear on edges and objects in contact with other surfaces.

Parameters

Num Samples

Controls the number of samples used to calculate curvature. More samples can reduce the noise at the cost of increased render time.

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Sample spread of rays when using cosine distribution. A value of 1.0 gives a perfect Lambertian distribution. Lower values shrink or "tighten" the effect along curves while larger amounts spread out the effect.

Bias

The bias will affect the falloff of the curvature and will be linear, decreasing with the distance from the shaded point. Bias can be used to take further samples into account more or less while nearby points have more weight.

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Convex Threshold

Increasing this parameter erodes the result, shrinking the visible effect.

Concave Threshold

Increasing this parameter erodes the result, shrinking the visible effect.

Output

Output Gain

A multiplier for the resulting curvature effect (areas without curvature are naturally unaffected)

Output Type

Set to "Concave", only concave curvature will be output. Set to "Convex", only convex curvature will be output. "Both" will show both convex and concave curvature.

Monochrome Output

The result is a simple white or greyscale value for both concave and convex results. Off outputs Convex as Red and Concave as Green

Image Added

Clamp Output

Values are clamped to 0-1 ranges by default. If you require an expanded range (perhaps with the gain control or to drive another parameter connection) you can disable this.