produces focused light and shadow effects from light passing through a transparent object.

Caustic Refraction through glass.

Caustics refers to the bending and refraction of light when passing through transparent materials.

Caustics can be set for a transparent material on the Material Wizard , or using Object Properties - in IRender Plus mode.

Caustic Refraction

Caustic image after 20 passes
Caustic image after 100 passes
A caustic is the envelope of light rays reflected or refracted by a curved surface or object, or the projection of that envelope of rays on another surface.

The Caustic effect produces focused light and shadow effects from a point light.

This is a glass bowl of apples, (with a pyramid procedural bump effect), and a glass cone, rendered with transparency and refraction, and with Caustic effects. (Reflection 0.90, refraction 1.15).

These scene is illuminated with a spotlight.

Note: Caustic does not currently work with the Sun for illumination. This scene was illuminated with a spotlight.

Normal Refraction


This is the same model but no Caustic effects.

Note that with the Normal setting, objects which are highly transparent do not cast appreciable shadows.

See Also