Parameters

Num Samples

Controls the number of samples used to calculate curvature per camera hit point. More samples reduces can the noise at the cost of increased render time.

Sample Distribution

Possible values are uniform and cosine (Lambertian).

Cosine Spread

Sample spread of rays when using cosine distribution. A value of 1.0 gives a perfect Lambertian distribution.

Bias

The bias will affect the falloff of the curvature and will always be linear, decreasing with distance.

The closer to 0.0, only points closest to the shading point will contribute.

With the default of 0.5 any points close to Max Distance will contribute less, and points close to the shaded point will contribute more. 

The closer to 1.0, the more all sampled points will contribute. At exactly 1.0 sampled points at all distance will contribute equally.

Falloff

Falloff can be used to control the softness of the occlusion effect.

Max Distance

The max distance at which objects may occlude. Zero is infinite (all objects occlude).

Direction

Trace rays in the direction of the surface normal (outside), inverse to the normal (inside), or in both directions.

Bias Normal

Add a directional bias to the normal vector. Values must be specified in world space.