In this work we introduce a new method for indexing 3D models. This method is based on the characterization of 3D objects by a set of 7 characteristic views, including three principals, and four secondaries. The primary, secondary, and tertiary viewing directions are determined by the eigenvector analysis of the covariance matrix related to the 3D object. The secondary views are deduced from the principal views. We propose an index based on "curvature scale space", organized around a tree structure, named M-Tree, which is parameterized by a distance function and allows one to considerably decrease the calculating time by saving the intermediate distances.