A Sweepline Algorithm for Generalized Delaunay Triangulations

We give a deterministic O(n log n) sweepline algorithm to construct the generalized Voronoi diagram for n points in the plane or rather its dual the generalized Delaunay triangulation. The algorithm uses no transformations and it is developed solely from the sweepline paradigm together with greediness. A generalized Delaunay triangulation can be based on an arbitrary strictly convex Minkowski distance function (including all L_p distance functions 1 < p < *) in contrast to ordinary Delaunay triangualations which are based on the Euclidean distance function

On the construction of abstract Voronoi diagrams, II

Abstract Voronoi Diagrams are defined by a system of bisecting curves in the plane, rather than by the concept of distance [K88a,b]. Mehlhorn, Meiser, Ó\u27Dúnlaing [MMO] showed how to construct such diagrams in time O(n log n) by a randomized algorithm if the bisecting curves are in general position. In this paper we drop the general position assumption. Moreover, we show that the only geometric operation in the algorithm is the construction of a Voronoi diagram for five sites. Using this operation, abstract Voronoi diagrams can be constructed in a purley combinatorial manner. This has the following advantages. On the one hand, the construction of a five-site-diagram is the only operation depending on the particular type of bisecting curves and we can therefore apply the algorithm to all concrete diagrams by simply replacing this operation. On the other hand, this is the only operation computing intersection points; thus, problems arising from instable numerical computations can occur only there

On the construction of abstract Voronoi diagrams, II

Abstract Voronoi Diagrams are defined by a system of bisecting curves in the plane, rather than by the concept of distance [K88a,b]. Mehlhorn, Meiser, Ó'Dúnlaing [MMO] showed how to construct such diagrams in time O(n log n) by a randomized algorithm if the bisecting curves are in general position. In this paper we drop the general position assumption. Moreover, we show that the only geometric operation in the algorithm is the construction of a Voronoi diagram for five sites. Using this operation, abstract Voronoi diagrams can be constructed in a purley combinatorial manner. This has the following advantages. On the one hand, the construction of a five-site-diagram is the only operation depending on the particular type of bisecting curves and we can therefore apply the algorithm to all concrete diagrams by simply replacing this operation. On the other hand, this is the only operation computing intersection points; thus, problems arising from instable numerical computations can occur only there