A traditional ambient occlusion effect can be accomplished by setting the occluded color to black and unoccluded color to white.

Parameters

Occluded and Unoccluded

Resulting colors for occluded and unoccluded shading.

Num Samples

Controls the number of occlusion samples 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.

Falloff

Falloff values greater than zero create a softer look. Values less than zero give a hard edge when combined with max distance.

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.