1.6.13 Shape Similarity

Problem Input | Problem Output

INPUT                    OUTPUT


Input Description: Two polygonal shapes, P_1 and P_2.

Problem: How similar are P_1 and P_2?

Excerpt from The Algorithm Design Manual: 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.


Implementations

  • SNNS - Stuttgart Neural Network Simulator (C) (rating 7)
  • Shape similarity testing via turning functions (C) (rating 6)
  • GMT - Graph Matching Toolkit (Binary) (rating 5)

    Related Problems

  • Graph Isomorphism
  • Medial-Axis Transformation


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    This page last modified on Wed Mar 07, 2001 .