Practical distribution-sensitive point location in triangulations

  • Authors:
  • Pedro Machado ManhãEs De Castro;Olivier Devillers

  • Affiliations:
  • Centro de Informática (CIn) da Universidade Federal de Pernambuco (UFPE), Av. Jornalista Anibal Fernandes, s/n - Cidade Universitária (Campus Recife) 50.740-560, Recife, Pernambuco, Braz ...;INRIA, 2004 route des lucioles BP 93, 06902 Sophia Antipolis, France

  • Venue:
  • Computer Aided Geometric Design
  • Year:
  • 2013

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Abstract

We design, analyze, implement, and evaluate a distribution-sensitive point location algorithm based on the classical Jump & Walk, called Keep, Jump, & Walk. For a batch of query points, the main idea is to use previous queries to improve the current one. In practice, Keep, Jump, & Walk is actually a very competitive method to locate points in a triangulation. We also study some constant-memory distribution-sensitive point location algorithms, which work well in practice with the classical space-filling heuristic for fast point location. Regarding point location in a Delaunay triangulation, we show how the Delaunay hierarchy can be used to answer, under some hypotheses, a query q with an O(log#(pq)) randomized expected complexity, where p is a previously located query and #(s) indicates the number of simplices crossed by the line segment s. The Delaunay hierarchy has O(nlogn) time complexity and O(n) memory complexity in the plane, and under certain realistic hypotheses these complexities generalize to any finite dimension. Finally, we combine the good distribution-sensitive behavior of Keep, Jump, & Walk, and the good complexity of the Delaunay hierarchy, into a novel point location algorithm called Keep, Jump, & Climb. To the best of our knowledge, Keep, Jump, & Climb is the first practical distribution-sensitive algorithm that works both in theory and in practice for Delaunay triangulations.