Technical Reports

The ICICS/CS Reading Room

UBC CS TR-90-17 Summary

Polygon Triangulation in $0(N \log \log N)$ Time with Simple Data Structures, June 1990 David G. Kirkpatrick, Maria M. Klawe and Robert E. Tarjan

We give a new $O (n \log \log n )$-time deterministic algorithm for triangulating simple $n$-vertex polygons, which avoids the use of complicated data structures. In addition, for polygons whose vertices have integer coordinates of polynomially bounded size, the algorithm can be modified to run in $O (n \log^{*} n )$ time. The major new techniques employed are the efficient location of horizontal visibility edges that partition the interior of the polygon into regions of approximately equal size, and a linear-time algorithm for obtaining the horizontal visibility partition of a subchain of a polygonal chain, from the horizontal visibility partition of the entire chain. The latter technique has other interesting applications, including a linear-time algorithm to convert a Steiner triangulation of a polygon into a true triangulation.

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