An illumination planner for Lambertian polyhedral objects

The measurement of shape is a basic object inspection task. We use a noncontact method to determine shape called photometric stereo. The method uses three light sources which sequentially illuminate the object under inspection and a video camera for taking intensity images of the object. A significant problem with using photometric stereo is determining where to place the 3 light sources and the video camera. In order to solve this problem, we have developed an illumination planner that determines how to position the three light sources and the video camera around the object. The planner determines how to position light sources around an object so that we illuminate a specified set of faces in an efficient manner and so that we obtain an accurate measurement. From a high level, our planner has three major inputs: the CAD model of the object to be inspected, a noise model for our sensor, and a reflectance model for the object to be inspected. We have experimentally verified that the plans generated by the planner are valid and accurate