Linked from
The 17 pages that link to Illuminance, each with the reason it gives.
Inverse-square lawRelated: For a point light source, illuminance falls with the square of distance.
Lighting designRelated: It quantifies how much light reaches a task surface.
Theatrical lightingRelated: It describes how much light reaches a performer or scenic surface.
Stage lightingRelated: It helps specify how brightly performers or scenery are lit.
LightRelated: Illuminance measures human-weighted brightness, not every biological effect of light.