3D DIGITIZATION OF HERITAGE: PHOTOMETRIC STEREO CAN HELP

Abstract. There are mainly two families of photographic 3D reconstruction. Photogrammetry techniques work according to the principle of triangulation, from the matching of different views, while photometric techniques link the appearance of a 3D point to the orientation of its normal, relative to the direction of the incident light. While photogrammetry allows to find the global shape of a 3D scene, if it is sufficiently textured, photometric techniques highlight the details of the relief, as long as the model linking the lighting to the shape and reflectance of the scene is sufficiently realistic. In order to avoid errors in the 3D models obtained, all the photographic techniques of 3D reconstruction have benefited, over the years, from algorithmic improvements that make them more and more robust to outliers or unreliable data. Moreover, the complementarity between these two types of approaches having been identified for a long time, many solutions have been proposed to merge them. Our work aims at providing the free and open-source photogrammetry software Meshroom with the benefits it could get from photometric stereo, particularly in the context of the 3D digitization of heritage, knowing that it is the only photometric technique for 3D reconstruction that has really proven itself.