1. A method for representing a class of objects, comprising: acquiring a set of samples for the objects in the class, there being one sample for each object, and each sample includes a plurality of data values representing characteristics of the object; grouping the samples into subsets such that each subset intersects at least one other subset; determining, for each subset, a low-dimensional subset parameterization; and averaging nullspaces of the low-dimensional subset parameterizations to obtain a matrix having a nullspace containing a low-dimensional representation of the class of objects.