Determining Intrinsic Dimension and Entropy of High-Dimensional Shape Spaces
Jose A. Costa, Alfred O. Hero · Modeling and simulation in science, engineering & technology · 2006
Given a finite set of random samples from a smooth Riemannian manifold embedded in ℝ d , two important questions are: what is the intrinsic dimension of the manifold and what is the entropy of the underlying sampling distribution on the manifold? These questions naturally arise in the study of shape spaces generated by images or signals for the purposes of shape classification, shape compression, and shape reconstruction. This chapter is concerned with two simple estimators of dimension and entropy based on the lengths of the geodesic minimal spanning tree (GMST) and the k -nearest neighbor ( k -NN) graph. We provide proofs of strong consistency of these estimators under weak assumptions of compactness of the manifold and boundedness of the Lebesgue sampling density supported on the manifold. We illustrate these estimators on the MNIST database of handwritten digits.