Quantity defined by the formula

where dΦv is the luminous flux transmitted by an elementary beam passing through the given point and propagating in the solid angle dΩ containing the given direction; dA is the area of a section of that beam containing the given point; θ is the angle between the normal to that section and the direction of the beam.
Unit: cd*m^(2) = lm*m^(-2)*sr^(-1)