The upper envelope of Voronoi surfaces and its applications

Given a set S of sources (points or segments), we consider the surface that is the graph of the function d(x) - min_p∈s ρ(x,p), for some metric ρ. This surface is closely related to the Voronoi diagram, Vor(S), of S under the metric ρ. The upper envelope of a set of these Voronoi surfaces, each defined for a different set of sources, can be used to solve a number of problems, including finding the minimum Hausdorff distance between two sets of points or segments under translation, and determining the optimal placement of a site with respect to sets of utilities. We derive bounds on the number of vertices on the upper envelope of m Voronoi surfaces, provide efficient algorithms to calculate these vertices, and discuss applications to the aforementioned problems.