| luminance coefficient multiplied by the cube of the cosine of the angle of incidence of the light on a point on a surface Note 1 to entry: The reduced luminance coefficient can be expressed by the equation r = q(cos ε)3 where q is the luminance coefficient in steradian to the power minus one (sr−1), and ε is the angle of incidence in degree (°).
Note 2 to entry: The angle of observation, α, affects the value of r. By convention this angle is fixed at 1° for road lighting calculations. Note 3 to entry: The reduced luminance coefficient is expressed in steradian to the power minus one (sr−1).
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