“…An unconstrained photometric-stereo method for estimating the surface normal and the surface reflectance of objects without a priori knowledge of the light source directions was proposed in [7]. Also, worth mentioning the work in [16,9,29] that are based on similar approaches. Recently approaches for 3D reconstruction based on photometric stereo with unknown lighting were proposed [4,25,1,26,31,22,21,27].…”