The many benefits of a full cutoff design Lighting distribution graphic of full cutoff and non cutoff lighting This graphic indicates the lighting distribution of a full cutoff fixture and a globe style non-cutoff fixture. No direct light would be emitted and no glare would be seen above the horizontal line. Full strength light and glare are emitted below the diagonal. In the lower illustration the non-cutoff offers no directional control, except that the fixture base and pole block illumination from the area near the pole base.
Light diminishes exponentially over distance according to the inverse squares law.
Glare's effect , however, does not diminish to the same extent, and causes problems at far greater distances. See IDA Information Sheet No. 78 for a more detailed discussion. Increases driver and pedestrian safety by greatly reducing glare in the horizontal plane which forms our field of view as we drive and move about in vertical positions. Provides directional control against light spillage onto other property. Reduces urban skyglow.