The light intensity distribution curve is obtained by taking a section through the light intensity distribution, which represents the light intensity of a light source for all solid angles. With rotationally symmetrical light sources, the luminous intensity distribution can be shown by a single light intensity distribution curve, whereas two or more curves are required for axially symmetrical light sources. The light intensity distribution curve is generally expressed in the form of a polar coordinate diagram, but with projectors it is often shown in Cartesian coordinates.