Compensating for the reflectance of the human face

A structured light imaging system is being developed which is capable of accurately recovering the three-dimensional surface of the human face. In structured light, a uniform square grid pattern is projected onto the face, and an image of this pattern is recorded using a single solid-state camera. By locating the intersections of the grid stripes and matching them correctly to the projected grid patterns, the three-dimensional positions of points on the face can be determined by triangulation. One of the major problems in locating the intersections of the grid pattern is the brightness variation due to the variations in the reflectivity of the human face. A solution to this problem is presented which is based on a simple statistical approximation of the reflectivity. A set of experiments is reported showing that the reflectance compensation improves the image processing used to detect and match the intersections.<>