Finding a minimum medial axis of a discrete shape is NP-hard

  • Authors:
  • David Coeurjolly;Jérôme Hulin;Isabelle Sivignon

  • Affiliations:
  • LIRIS, UMR CNRS 5205, Université Claude Bernard Lyon 1, F-69622 Villeurbanne, France;LIF, UMR CNRS 6166, Université de la Méditerranée, 163, av. de Luminy F-13288 Marseille, France;LIRIS, UMR CNRS 5205, Université Claude Bernard Lyon 1, F-69622 Villeurbanne, France

  • Venue:
  • Theoretical Computer Science
  • Year:
  • 2008

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Abstract

The medial axis is a classical representation of digital objects widely used in many applications. However, such a set of balls may not be optimal: subsets of the medial axis may exist without changing the reversivility of the input shape representation. In this article, we first prove that finding a minimum medial axis is an NP-hard problem for the Euclidean distance. Then, we compare two algorithms which compute an approximation of the minimum medial axis, one of them providing bounded approximation results.