Two Components of Illumination

Every object in a scene is potentially a source of light. Light may be either be emitted or reflected from objects. Generally, in computer graphics we make a distinction between light emitters and light reflectors. The emitters are called light sources, and the reflectors are usually the objects being rendered. Light sources are characterized by their intensities while reflectors are characterized by their material properties.

Light Sources

  • Emittance Spectrum (colour)

  • Geometry (position and direction)

  • Directional Attenuation

Surface Properties

  • Reflectance Spectrum (colour)
    for different aspects of illumination

  • Geometry (position, orientation, and micro-structure)

  • Absorption