Using frontier points to recover shape, reflectance and illumination

We describe a method to recover the surface reflectance and the 3-d shape of a non-Lambertian object as well as illumination, from a collection of images. It is based on the so-called frontier points, which are extracted from the outlines of an object. Frontier points provide 3-d locations on the object surface where the surface normal is known. This information is exploited to infer the surface reflectance of the object and the light distribution of the scene both under varying illumination and fixed vantage point, and under varying vantage point and fixed illumination. We also show how to apply frontier points for shape recovery in photometric stereo. The effectiveness of frontier points for recovering reflectance, illumination and shape is confirmed by a number of experiments on both real and synthetic data.