Light luminous intensity is a measure of the amount of light emitted in a unit
of time per solid angle.
In SI, unit of luminous intensity is candela (candle, cd). A candle emits light
with a luminous intensity of one candela. Other main luminous intensity unit is
lumen per steradian which is the amount of light from a source in one second. 1
candela equals 1 lumen per steradian.