Steiner hull algorithm for the uniform orientation metrics

  • Authors:
  • Christian Wulff-Nilsen

  • Affiliations:
  • Department of Computer Science, University of Copenhagen, DK-2100 Copenhagen, Denmark

  • Venue:
  • Computational Geometry: Theory and Applications
  • Year:
  • 2008

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Abstract

Given a set Z of n=2, we consider the problem of finding a @l-Steiner hull of Z, i.e., a region containing every Steiner minimal tree for Z in the @l-metric. We define a @l-Steiner hull @l-SH(Z) of Z as a set obtained by a maximal sequence of removals of certain open wedge-shaped regions from an initial hull followed by a simplification of its boundary. A perhaps surprising result is presented, namely that a Euclidean MST for Z can be used to decompose the problem of finding @l-SH(Z) into subproblems. Each of these can then be solved recursively using linear searches combined with a sweep line approach. Using this result, we present an algorithm computing @l-SH(Z). This algorithm has O(@lnlogn) running time and O(@ln) space requirement which is optimal for constant @l. We prove that @l-SH(Z) is independent of the order of removals of the open wedge-shaped regions.