Dense Point Sets Have Sparse Delaunay Triangulations or “... But Not Too Nasty”

  • Authors:
  • Jeff Erickson

  • Affiliations:
  • Department of Computer Science, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA

  • Venue:
  • Discrete & Computational Geometry
  • Year:
  • 2005

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Abstract

The spread of a finite set of points is the ratio between the longest and shortest pairwise distances. We prove that the Delaunay triangulation of any set of $n$ points in~$\Real^3$ with spread $\Delta$ has complexity $O(\Delta^3)$. This bound is tight in the worst case for all $\Delta = O(\sqrt{n})$. In particular, the Delaunay triangulation of any dense point set has linear complexity. We also generalize this upper bound to regular triangulations of $k$-ply systems of balls, unions of several dense point sets, and uniform samples of smooth surfaces. On the other hand, for any $n$ and $\Delta = O(n)$, we construct a regular triangulation of complexity $\Omega(n\Delta)$ whose $n$ vertices have spread $\Delta$.