Houdini 13.0 Nodes

interface version 2

Calculates ambient occlusion and stores it in per-point attribute(s).

This operator calculates ambient occlusion. It also can be tuned to compute “edge maps”.

  • Occlusion attribute calculated for the stanford dragon model.

  • An example set of parameters for computing an "edge map".

Note

This is a “naive” implementation (without any acceleration techniques), so it can be slow for large number of samples.

Some recommended workarounds are

  • Post-process (blur) the resulting attribute(s)

  • Compute occlusion for a lower-resolution model, then transfer the results

  • A Scatter SOP driven by the calculated occlusion attribute.

Parameters

Parameters

Settings for the ambient occlusion computation.

Tip

Make sure geometry normals are correct (i.e. pointing outwards).

Max Distance

Sampling radius for the ambient occlusion.

Normal Attrib

If enabled, this (per-point vector) attribute will be used as surface normal for the computations. (Also see tip about normals above.)

Flip Normal Direction

Reverses the surface normal direction.

Tip

This can be useful for computing edge maps.

Angle, Exponent

Occlusion aperture cone angle. (The exponent value can be used to bias the ray distribution within the aperture cone.)

Num Samples

Number of occlusion rays to be cast. Can get very slow for large numbers.

Ray Bias

Self-intersection tolerance value.

Range, Exponent

Additional corrections on computed occlusion value.

Output

Output attribute settings. All attributes are per-point types.

Occlusion Attrib

Output occlusion as a per-point float attribute (in the [0..1] range).

Color Attrib

Map the Occlusion Attrib to a color ramp and output it as a color attribute.

Distance Attrib

Output the computed average distance as a float attribute. (The occlusion value is this value divided by Max Distance.)

Release Notes

interface version 2 —

2014-08-28

  • Added Flip Normal Direction toggle.

2014-06-10

Interface version 2, initial version.

  • Occlusion aperture is now specified with an angle

  • Better structured output options

  • Output attribute local variables are now properly defined

  • UI/Help card improvements, internal cleanups

  • Internal calculation is the same (slow)

interface version 1 —

Version 0.0.1

Initial version. (Slow – an alternative, pointcloud-based method would be much faster.)