Illumination Terminology

• Radiant power [flux] (F)

  • Rate at which light energy is transmitted (in Watts).

• Radiant Intensity (I)

  • Power radiated onto a unit solid angle in direction (in Watts/sr)
    • e.g.: energy distribution of a light source (inverse square law)

• Radiance (L)

  • Radiant intensity per unit projected surface area (in Watts/m2sr)
    • e.g.: light carried by a single ray (no inverse square law)

• Irradiance (E)

  • Incident flux density on a locally planar area (in Watts/m2 )
    • e.g.: light hitting a surface along a

• Radiosity (B)

  • Exitant flux density from a locally planar area (in Watts/ m2 )

Previous slide

Back to first slide

View graphic version