Luminance Calculator - Concepts
The Luminance value in cd/sq. m indicates the absolute diffuse Luminance of Emittance surfaces. Luminance is only available for the Emittance Surface Type, and is specified as a value between 1 and 30000. This specification allows you to set an absolute ‘brightness’ of the surface.
Lambertian (diffuse) Luminance is defined as Exitance / Pi. The following conversion factors are applied automatically in the Luminance Calculator:
|
Unit |
Width |
Conversion |
Example: |
|
|---|---|---|---|---|
|
Lumen / Square Ft |
Included |
Multiply by 10.76 (Sq Ft to Sq M conversion); divide by Pi (3.14159265) |
100 Lumen / Square Ft |
= 100 * 10.76 / 3.14159265 = 342.451 Cd / Square M |
|
Lumen / Square Meter |
Included |
Multiply by 10.76 (Sq Ft to Sq M conversion); divide by Pi (3.14159265) |
100 Lumen / Square Meter |
= 100 / 3.14159265 = 31.831 Cd / Square M |
|
Lumen / Linear Ft |
0.042 Ft |
Multiply by 10.76 (Sq Ft to Sq M conversion); divide by (Pi (3.14159265) multiplied by calculated Square footage) |
100 Lumen / Linear Ft |
= 100 * 10.76 / (3.14159265* 0.042 Sq Ft) = 8153.584 Cd / Square M |
|
Lumen / Linear Meter |
0.015 Meter |
Multiply by 10.76 (Sq Ft to Sq M conversion); divide by (Pi (3.14159265) multiplied by calculated Square meterage) |
100 Lumen / Linear Meter |
= 100 / (3.14159265* 0.015 Sq M) = 2122.066 Cd / Square M |
Note: If the luminance exhibited by the Emittance surface is not essentially diffuse, this assumption of Luminance will yield inaccurate simulations. You must obtain a photometric file from the manufacturer describing the candela distribution to use instead.
Backward compatibility: Emittance Factor in older version files will be used as the Luminance value (e.g. Emittance Factor = 10, Luminance = 10 cd/sq.m). It may be necessary to change this value in order to achieve desirable results. This also applies to emittance surfaces in older version library objects.