Facial Reflectance Measurements from Single Images using Shape-from-shading

In this paper we show how to estimate facial surface reflectance properties (a slice of the BRDF and the albedo) in conjunction with facial shape from a single image. We show how an estimate of the surface reflectance function can be made by fitting a curve to the scattered and noisy reflectance samples provided by the estimated shape. We present a novel statistical face shape constraint which we term ‘model-based integrability’ which we enforce on the field of surface normals. We iteratively interleave the two processes of estimating reflectance properties based on the current shape estimate and updating the shape estimate based on the current estimate of the reflectance function. We show that the method is capable of recovering accurate shape and reflectance information from single images using both synthetic and real world imagery.