A Straight Skeleton Approximating the Medial Axis

  • Mirela Tănase
  • Remco C. Veltkamp
Part of the Lecture Notes in Computer Science book series (LNCS, volume 3221)


We propose the linear axis, a new skeleton for polygonal shapes. It is related to the medial axis and the straight skeleton, being the result of a wavefront propagation process. The wavefront is linear and propagates by translating edges at constant speed. The initial wavefront is an altered version of the original polygon: zero-length edges are added at reflex vertices. The linear axis is a subset of the straight skeleton of the altered polygon. In this way, the counter-intuitive effects in the straight skeleton caused by sharp reflex vertices are alleviated. We introduce the notion of ε-equivalence between two skeletons, and give an algorithm that computes the number of zero-length edges for each reflex vertex which yield a linear axis ε-equivalent to the medial axis. This linear axis and thus the straight skeleton can be computed from the medial axis in linear time for polygons with a constant number of “nearly co-circular” sites. All previous algorithms for straight skeleton computation are sub-quadratic.


Voronoi Diagram Medial Axis Voronoi Cell Simple Polygon Linear Axis 
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Copyright information

© Springer-Verlag Berlin Heidelberg 2004

Authors and Affiliations

  • Mirela Tănase
    • 1
  • Remco C. Veltkamp
    • 1
  1. 1.Institute of Information & Computing SciencesUtrecht UniversityThe Netherlands

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