Lamp Intensity Dialog Box

Use this dialog box to modify the brightness of a lamp for a photometric light.

Lamp intensity represents the luminous intensity, or power in a particular direction.

Intensity

Use to enter the desired amount of light.

Unit

Specify the intensity unit. Choose from:

• Intensity (candela). Luminous intensity measured in candela (cd). Specifies the amount of light produced by a source in a specific direction.
• Flux (lumen). Luminous flux, measured in lumens (lm). Specifies the total amount of light produced by a source without regard to direction. This information is typically provided by lamp manufacturers. 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 web light, there isn't any analytical formula. The flux is obtained by numerically integrating the intensities provided in the web file.
• Illuminance (lux). Illuminance, measured in lux, and represents the quantity of light arriving at a surface (Area-flux-density). When this option is selected, the Distance field becomes available.
• Wattage (watt). A measurement of the electrical power consumed by a light source. When this option is selected, the Efficacy field becomes available.

Distance

lluminance is affected by the distance from the light source to the surface. Use this field to adjust the value.

Efficacy

The amount of light (luminous flux, measured in lumens) produced by a light source as a ratio of the amount of energy consumed to produce it (measured in watts).

Pointing device: Autodesk Rendering window > Lighting tab > General section > Lamp Intensity