How to understand photometric polar diagrams
If you are working in the lighting industry sooner or later you will come across photometric diagrams and you must know how to interpret them. This blog entry page is quick introduction on how to look at a photometric diagram and get important information from it. Often photometric diagrams use the C-Gamma system. Gamma=0 points downwards towards the floor or road. Gamma=180 points upwards to the ceiling or sky. Here is a C-Gamma diagram with some of the luminous intensity “rays of light” left in: The "rays" make the diagram more confusing than it needs to be and photometric diagrams always leave out those “rays” to give you a simpler diagram as shown below: The point to remember is that the distance from the center of the diagram to one of the points on the “outline” corresponds to a luminous intensity value, often in candelas, in the given direction. These diagrams ...