2011

Summary
Dialog box for setting the Lamp Intensity for a photometric light.
List of Options
The following options are displayed.
Lamp Intensity Represents the brightness of a lamp. More specifically, it
represents the luminous intensity, or power in a particular direction. It is
specified in candela by default (in both the SI and American units systems).
Must select from one of the following radial buttons:
■ Intensity (Candela). Specifies the number of candelas (cd) is the SI unit of
luminous intensity (perceived power emitted by a light source in a
particular direction).
■ Flux (Lumen). Represents the rate of total energy leaving the lamp. It is
specified in lumens (SI and American). Mathematically, the flux is the
integral of the luminous intensity over the sphere. The calculation of flux
depends on the distribution of intensities. For a point light with constant
intensity, the flux is simply the product of the intensity and the solid angle
of a sphere: 4 Pi * Intensity. For a spot light, the flux is the product of the
intensity and the solid angle of the hotspot cone, plus the incremental
solid angle of the fall-off region. For a weblight, there isn’t any analytical
formula. The flux is obtained by numerically integrating the intensities
provided in the web file.
■ Illuminance (Foot-candles). Represents the energy per area arriving at a
surface (Area-flux-density). It is specified in lux (SI) and foot-candles
(American). For a near light, because the light rays are diverging, you have
Lighting Properties | 1547