• Radiant energy

    • Radiant energy is “total # of hits” anywhere in the scene over the complete duration of the scene
    • This quantity captures the total energy/* of all the photons hitting the scene
    • Unit: Joules (J)
  • Radiant flux

    • Energy per second (power)
    • Unit: Joules per second () = Watts ()
  • Radiant energy density

    • Energy per unit area
    • Unit: Joules per square meter ()
  • Irradiance/Radiant Exitance

    • flux per unit area incident on a surface
    • Unit: Watts per square meter ()
    • Irradiance: flux arriving a surface
    • Radiant Exitance: flux leaving a surface
  • Radiance

    • Power per unit area, per steradian (solid angle unit)
    • Unit ()
    • It is the solid angle density of irradiance