Automatic tracing of photometric curves

Abstract

A method is described of drawing photometric curves (e.g. isolux, isoluminance curves) for any given lighting system directly through a computer. Particular reference is made to the calculation of illuminance and isolux curves in street lighting. The method consists essentially in calculating the illuminances for a discrete series of points defining an ideal lattice on the road surface, and in direct tracing through a plotter of the isolux curves by linear interpolation of the data obtained. The luminaires are characterized by their luminous intensity distributions. Provision is made for an arbitrary inclination of the optical axis of the luminaire and for any working condition. The application of the method to lighting installations with multiple sources is also considered.