Houdini 16.5 Nodes VOP nodes

Occlusion VOP node

Computes ambient occlusion at the point P with the normal N.

This operator computes ambient occlusion at the point P with the normal N. Just as in the Irradiance operator, the hemisphere is sampled. However, unlike Irradiance, Occlusion ensures that surfaces which are intersected during the hemisphere sampling are not shaded.

For this function to work properly, either a constant background color (bgcolor) or an environment map (envmap) must be specified. Most likely, it will be necessary to specify a transform space (envobj) for the environment map evaluations. Also, if an environment map is specified, it is possible to tint the resulting color (tint).

Other parameters include the Bias (bias), which gives control over self-intersections, and Number Of Samples (samples), which specifies the amount of samples should be sent out to filter rays.

If the position (P) and normal vector (N) are not connected, the global variables by the same names will be used instead. If the maximum ray distance (maxdist) is not connected, the rays will be allowed to travel to infinity.

The Object Scope parameter is a list of object names to occlude, and the Object Selection parameter is a list of categories to occlude.

See how to create an environment/reflection map.


The occlusion() operation does not accept a per-point maximum distance. This value needs to be a constant.

See also

VOP nodes