Calibration of light sources

We present a methodology for calibrating multiple light source locations in 3D from images. The procedure involves the use of a novel calibration object that consists of either 2 or 3 spheres at known relative positions. There are two variants of the process: one which uses range and intensity imaging to find the positions of the light sources, and one that uses only the intensity image to locate the illuminants. We conducted experiments using both variations of the technique to locate light sources in 51 different positions in a laboratory setting. Our data shows that the vector from a point in the scene to a light source can be measured to within 3°(6%) of its tote direction and within 0.13 m (9%) of its true magnitude compared to empirically measured ground truth. Finally, we demonstrate how light source information can be applied to burn scar color correction and color segmentation