Point calculation methods are used to determine the illuminance at a specific point on a work plane or surface. Point calculations are often done to determine the uniformity of illumination ratios or the illuminance on vertical surfaces such as a building facade. Exterior point calculations include only a direct contribution from the source. Indirect contributions from reflected surfaces are usually insignificant.
Maximum uniformity ratios for parking lots and roadways are specified by IES. Uniformity of illumination is important for visual perception especially in high-speed performance tasks. Poor uniformity can distort both the speed and position of objects. IES provides recommendations for the average to minimum uniformity ratio depending on the road and parking lot classifications.
Select from the following . . .
Concept of Point Calculation
Inverse Square Law
ISL for Source Non-Perpendicular
For Non-Point Source|
For Vertical Surface
Point Calculation Conclusion