Luminous intensity is the concept for the concentration of light in a specific direction, radiated per second.
It is designated by the symbol I. The unit is the candela (cd).
The luminous intensity can be defined as:
The luminous flux in a certain direction, radiated per unit of solid angle.
1 candela = 1 lumen / steradian
Intensity is not a function of distance
The photometrical performances of a luminaire are derived from the luminaire’s measured luminous intensity distribution. These measurements of luminous intensity are carried out in specialised laboratories, using goniophotometers.