Space/query-time tradeoff for computing the visibility polygon

  • Authors:
  • Mostafa Nouri Baygi;Mohammad Ghodsi

  • Affiliations:
  • Computer Engineering Department, Sharif University of Technology, Tehran, Iran and IPM School of Computer Science, Tehran, Iran;Computer Engineering Department, Sharif University of Technology, Tehran, Iran and IPM School of Computer Science, Tehran, Iran

  • Venue:
  • Computational Geometry: Theory and Applications
  • Year:
  • 2013

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Abstract

In this paper, we consider the problem of computing the visibility polygon (VP) of a query point q (or VP(q)) in a scene consisting of some obstacles with total complexity of n. We show that the combinatorial representation of VP(q) can be computed in logarithmic time by preprocessing the scene in O(n^4logn) time and using O(n^4) space. We can also report the actual VP(q) in additional O(|VP(q)|) time. As a main result of this paper, we will prove that we can have a tradeoff between the query time and the preprocessing time/space. In other words, we will show that using O(m) space, we can obtain O(n^2log(m/n)/m) query time, where m is a parameter satisfying n^2=