“…In the present state-of-the-art, the concept of geodesic shape averaging allows unbiased constructions of atlases through diffeomorphic methods [12,2,17], i.e., the transformation of a reference shape toward an average (the geometry of the atlas) follows a geodesic path on a Riemannian manifold (the space of diffeomorphic transformations). While the LDDMM [4,3,6] or forward scheme approaches [1,8] provide elegant mathematical frameworks for averaging shapes, these methods could be slow and find their limitations with high shape variability. Guimond et al [10] proposed a fast and efficient algorithm [19,16,26] with sequential (pairwise) registrations to a reference image.…”