The.Algorithm.Design.Manual.Springer-Verlag.1998

Shape Similarity
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Shape Similarity
Input description: Two polygonal shapes, and .
Problem description: How similar are and ?
Discussion: Shape similarity is a problem that underlies much of pattern recognition. Consider a system
for optical character recognition (OCR). We have a known library of shape models representing letters
and the unknown shapes we obtain by scanning a page. We seek to identify an unknown shape by
matching it to the most similar shape model.
The problem of shape similarity is inherently ill-defined, because what ``similar'' means is application
dependent. Thus no single algorithmic approach can solve all shape matching problems. Whichever
method you select, expect to spend a large chunk of time tweaking it so as to achieve maximum
performance. Don't kid yourself - this is a difficult problem.
Among your possible approaches are:
● Hamming Distance - Assume that your two polygons have been overlaid one on top of the other.
The Hamming distance measures the area of symmetric difference between the two polygons, in
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