to a first preferred embodiment of the present invention the preferred embodiments relate specifically to matching of faces but the skilled person will be aware that the principles of the present invention are applicable to any geometric body having a three dimensional structure apparatus 10 comprises a three dimensional scanner 12 for obtaining three dimensional topographical data of the body several types of scanner are described hereinbelow together with brief discussions of how to process data therefrom in some of the cases data from the three dimensional scanner 12 is passed to a triangulator 14 the triangulator may perform triangulation on the data received from the scanner in order to generate a three dimensional triangulated manifold to represent the topological features of the body the exact operation of the triangulator to derive the manifold may vary depending on the way in which the 3d information is gathered in certain cases the manifold may be formed directly from the gathered data without the need for any intervening processing stage the manifold preferably represents all of the three dimensional topology of the body and therefore is in theory sufficient for allowing matching however in practice direct comparisons using the triangulated manifold have a number of disadvantages as will be demonstrated in the results given hereinbelow they requires a large amount of calculation matching does not distinguish reliably between different faces moreover matching generally fails when the same face has a different expression and matching is unreliable even.