A ratio from a calculation grid or field measurements that shows how even the lighting is. Interior standards commonly ask for a minimum to average ratio of 0.4 to 0.7 depending on the task; outdoor and parking criteria are often written as maximum to minimum, such as 10:1 or 20:1. Poor uniformity makes spaces look patchy and forces eyes to readapt, even when the average looks fine.
Average is fine but uniformity is 25 to 1 between poles, the pole spacing is too wide for that optic.
Also heard as
- uniformity ratio
- max:min
- min:avg
- Uo
Related terms
Illuminance
The amount of light falling on a surface per unit area, measured in lux or foot-candles.
Point-by-point
A lighting calculation that predicts illuminance at each point on a grid from every luminaire's photometric data.
Foot-candle
The North American working unit of light on a surface: one lumen falling evenly on each square foot.
Scallops
The arched pattern of light and shadow that downlights draw on a wall when mounted close to it.