1. A method for representing a 3D object with a descriptor, wherein a model of the 3D object is a 3D point cloud, comprising the steps of: locating a local support for each point p in the 3D point cloud, wherein the local support is a spherical volume S of points p i , centered on the point p and within a radius r of the point p according to 
 S={p i : ∥p i −p∥≦r}. generating reference x, y, and z axes for the local support; applying, according to the references x, y, and z axes, a polar grid along an azimuth and a radial directions on an xy plane centered on the point p such that each patch on the grid is a bin for a 2D histogram, wherein the 2D histogram is a 2D matrix F on the grid and each coefficient of the 2D matrix F corresponds to the patch on the grid; and estimating, for each grid location (k, l), an elevation value F(k, by interpolating the elevation values of the 3D points within the patches to produce the descriptor for the point p, wherein the steps are performed in a processor.