Overlaid oriented Voronoi diagrams and the 1-Steiner tree problem.

Overlaid oriented Voronoi diagrams (OOVDs) are known to provide useful data for the construction of optimal Euclidean $1$-Steiner trees. The theoretical time complexity of construction methods exploiting the OOVD is $O(n^2)$, but a computational study has never been performed, and robust constructions for OOVDs have not previously been implemented. In this paper, we outline a numerically stable implementation for constructing OOVDs using tools from the Computational Geometry Algorithms Library (CGAL), and test its performance on random point sets. We then study the effect that the OOVD data has in reducing the complexity of $1$-Steiner tree construction when compared to a naive approach. The number of iterations of the main loop of the 1-Steiner algorithm is directly determined by the number of faces in the OOVD, and this appears to be linear for the random inputs we tested. We also discuss methods for processing the OOVD data that lead to a reduction in construction time by roughly a factor of 12.