Placing the largest similar copy of a convex polygon among polygonal obstacles

  • Authors:
  • L. P. Chew;K. Kedem

  • Affiliations:
  • Department of Computer Science, Cornell University, Ithaca, NY;Department of Computer Science, Cornell University, Ithaca, NY

  • Venue:
  • SCG '89 Proceedings of the fifth annual symposium on Computational geometry
  • Year:
  • 1989

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Abstract

Given a convex polygon P and an environment consisting of polygonal obstacles, we find the largest similar copy of P that does not intersect any of the obstacles. Allowing translation, rotation, and change-of-size, our method combines a new notion of Delaunay triangulation for points and edges with the well-known functions based on Davenport-Schinzel sequences producing an almost quadratic algorithm for the problem. Namely, if P is a convex k-gon and if Q has n corners and edges then we can find the placement of the largest similar copy of P in the environment Q in time &Ogr;(k4n &lgr;4(kn) log n), where &lgr;4 is one of the almost-linear functions related to Davenport-Schinzel sequences. If the environment consists only of points then we can find the placement of the largest similar copy of P in time &Ogr;(k2n &lgr;3(kn) log n).