A fundamental discussion of 3-dimensional pattern matching using canonical angles between subspaces for the purpose of differentiating a face and its photograph.

Three-dimensional pattern recognition requires the definition of a similarity measure between 3-dimensional patterns. We discuss how to match 3-dimensional patterns, which are represented by a set of images taken from multiple directions and approximately represented by subspaces. The proposed method is to calculate the canonical angles between two subspaces. In order to differentiate an object and its photograph, at least a canonical angle other than the smallest one is required. We discuss the usage of the canonical angle both used by itself and combination, sum and product. We also demonstrate the effectiveness of the proposed method by experiments. © 2007 Wiley Periodicals, Inc. Syst Comp Jpn, 38(9): 11–20, 2007; Published online in Wiley InterScience (<URL>www.interscience.wiley.com</URL>). DOI 10.1002/scj.20786 [ABSTRACT FROM AUTHOR]