“…Beginning with the work of B. Horn [1,2,3], Shape from Shading (SfS), algorithms enjoy a long history in computing science research [4,5,6,7,8], continue to attract theoretical investigation in the field of computer vision [9,10,11,12,13,14,15,16,17,18,19,20] and find many practical applications, e.g. in planetary research (Photoclinometry), industrial automation, medical imaging or face recognition [21,22,23,24,25,26,27,28,29].…”