Page "Rendering (computer graphics)" Paragraph 67

Rendering is practically exclusively concerned with the particle aspect of light physics — known as geometric optics.

Treating light, at its basic level, as particles bouncing around is a simplification, but appropriate: the wave aspects of light are negligible in most scenes, and are significantly more difficult to simulate.

Notable wave aspect phenomena include diffraction ( as seen in the colours of CDs and DVDs ) and polarisation ( as seen in LCDs ).

Both types of effect, if needed, are made by appearance-oriented adjustment of the reflection model.