Exact Implementation of Arrangements of Geodesic Arcs on the Sphere with Applications

Recently, the Arrangement 2 package of Cgal, the Computational Geometry Algorithms Library, has been greatly extended to support arrangements of curves embedded on two-dimensional parametric surfaces. The general framework for sweeping a set of curves embedded on a two-dimensional parametric surface was introduced in [3]. In this paper we concentrate on the specific algorithms and implementation details involved in the exact construction and maintenance of arrangements induced by arcs of great circles embedded on the sphere, also known as geodesic arcs, and on the exact computation of Voronoi diagrams on the sphere, the bisectors of which are geodesic arcs. This class of Voronoi diagrams includes the subclass of Voronoi diagrams of points and its generalization, power diagrams, also known as Laguerre Voronoi diagrams. The resulting diagrams are represented as arrangements, and can be passed as input to consecutive operations supported by the Arrangement 2 package and its derivatives. The implementation is complete in the sense that it handles degenerate input, and it produces exact results. An example that uses real world data is included. Additional material is available at http://www.cs.tau.ac.il/~efif/VOS.