Illuminance falling on a horizontal plane 1m above and parallel to the playing surface.
Illuminance falling on a vertical plane 1m above and perpendicular to the playing surface.
The uniformity of illuminance in terms of how evenly light is distributed over a given reference plane. The uniformity of illuminance is expressed using two illuminance ratios: U1 and U2.
The total illuminance range, from minimum to maximum, that a person or camera will be exposed to. The U1 value contributes to visual performance.
The difference between a person’s normal adapted exposure and the lowest illuminance level on the given plane. The U2 value contributes to visual comfort.
The unit of illuminance incident on a pitch surface (1lx = 1lm/m2).
The quantity of light falling on a surface at a given point, measured in lux.