A method represents a class of objects. A set of samples for the objects in the class is acquired, there being one sample for each object, and each sample includes a plurality of data values representing characteristics of the object. The samples are grouped into subsets such that each subset intersects at least one other subset. For each subset, a low-dimensional parameterization is determined. Nullspaces of the low-dimensional parameterizations are averaged to obtain a matrix whose nullspace contains a low-dimensional representation of the class of objects.
