luminance coefficient, q

[11.5.19]

In roadway lighting:

At a surface of a medium, in a given direction, under specified conditions of illumination: The quotient of the luminance of the surface element in the given direction by the illuminance on the medium, expressed by:

    q = L/E ,

where:

    L is the luminance in cd/m2

    E is the illuminance in lx

Unit: sr-1

 

NOTE: This term was added in RP-16-17 Addendum 3.

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