Kinetic and dynamic data structures for convex hulls and upper envelopes

  • Authors:
  • Giora Alexandron;Haim Kaplan;Micha Sharir

  • Affiliations:
  • School of Computer Science, Tel Aviv University, Tel Aviv 69978, Israel;School of Computer Science, Tel Aviv University, Tel Aviv 69978, Israel;School of Computer Science, Tel Aviv University, Tel Aviv 69978, Israel, and Courant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA

  • Venue:
  • Computational Geometry: Theory and Applications
  • Year:
  • 2007

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Abstract

Let S be a set of n moving points in the plane. We present a kinetic and dynamic (randomized) data structure for maintaining the convex hull of S. The structure uses O(n) space, and processes an expected number of O(n^2@b"s"+"2(n)logn) critical events, each in O(log^2n) expected time, including O(n) insertions, deletions, and changes in the flight plans of the points. Here s is the maximum number of times where any specific triple of points can become collinear, @b"s(q)=@l"s(q)/q, and @l"s(q) is the maximum length of Davenport-Schinzel sequences of order s on n symbols. Compared with the previous solution of Basch, Guibas and Hershberger [J. Basch, L.J. Guibas, J. Hershberger, Data structures for mobile data, J. Algorithms 31 (1999) 1-28], our structure uses simpler certificates, uses roughly the same resources, and is also dynamic.