Note 1 to entry: Cylindrical illuminance is sometimes also defined as the arithmetic mean of the vertical illuminance E_v,v at a point

${\displaystyle E_{\text{v}\text{,c}}=\frac{1}{2\pi }{\displaystyle \underset{0}{\overset{2\pi }{\int }}{E}_{\text{v}\text{,v}}}\text{d}\phi }$

where E_v,v is the vertical illuminance for an area element with its normal in the direction φ, and φ is the angle in the plane perpendicular to the axis of the cylinder.

Note 2 to entry: The corresponding radiometric quantity is "cylindrical irradiance". The corresponding quantity for photons is "photon cylindrical irradiance".

Note 3 to entry: The cylindrical illuminance is expressed in lux (lx = lm·m⁻²).