Similarity Calculations and Applications for Low Beam Head Lamp Beam Patterns

A method to obtain a quantitative value for similarity between automotive beam patterns is presented. The use of the quantitative value for similarity is discussed in two contexts. First, similarity calculations are used to judge the correlation between computer predicted photometric performance and hardware photometric performance of Free-Form Reflector (FFR) low beam head lamps. A method for improving the similarity between hardware result and software prediction is discussed. In a second application, the similarity calculations are used to judge the resemblance of a benchmark beam pattern vs. three other beam patterns. In this application, we attempt to quantitatively judge whether a new “candidate” beam pattern exhibits similar behavior on the road as a benchmark or “goal” beam pattern. Finally, conclusions about the usage of beam pattern similarity are presented.