Two linear-time algorithms for computing the minimum length polygon of a digital contour

  • Authors:
  • J. -O. Lachaud;X. Provençal

  • Affiliations:
  • LAMA, UMR CNRS 5127, Université de Savoie, F-73376 Le Bourget du Lac, France;LAMA, UMR CNRS 5127, Université de Savoie, F-73376 Le Bourget du Lac, France and LIRMM, UMR CNRS 5506, Université Montpellier II, 161 rue Ada, F-34000 Montpellier, France

  • Venue:
  • Discrete Applied Mathematics
  • Year:
  • 2011

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Abstract

The Minimum Length Polygon (MLP) is an interesting first order approximation of a digital contour. For instance, the convexity of the MLP is characteristic of the digital convexity of the shape, its perimeter is a good estimate of the perimeter of the digitized shape. We present here two novel equivalent definitions of MLP, one arithmetic, one combinatorial, and both definitions lead to two different linear time algorithms to compute them. This paper extends the work presented in Provencal and Lachaud (2009) [26], by detailing the algorithms and providing full proofs. It includes also a comparative experimental evaluation of both algorithms showing that the combinatorial algorithm is about 5 times faster than the other. We also checked the multigrid convergence of the length estimator based on the MLP.