“…The 3D reconstruction of the spine in upright posture can be obtained by stereo-radiographic or bi-planar radiographic methods, developed since the 1970s [10,13,15,20,33,35,48,53,61]. The principle is to identify 4-25 anatomical landmarks per vertebrae, in two (or more) calibrated radiographs and to compute their 3D positions using algorithms such as DLT [13,48] or Non Stereo Corresponding Points [43].…”