@COMMENT {Autogenerated file by bib2html.pl version 0.94} @Article{ett-ijcga-2007, author = {Ioannis~Z. Emiris and Elias~P. Tsigaridas and George Tzoumas}, title = {{Predicates for the exact Voronoi diagram of ellipses under the Euclidean metric}}, journal = IJCGA, year = 2008, volume = 18, number = 6, pages = "567--597", editor = {N. Amenta and O. Cheong}, note = {(special issue devoted to SoCG 2007)}, abstract = " This article examines the computation of the Voronoi diagram of a set of ellipses in the Euclidean plane. We propose the first complete methods, under the exact computation paradigm, for the predicates of an incremental algorithm: \ka decides which one of two given ellipses is closest to a given exterior point; \kb decides the position of a query ellipse relative to an external bitangent line of two given ellipses; \kc decides the position of a query ellipse relative to a Voronoi circle of three given ellipses; \kd determines the type of conflict between a Voronoi edge, defined by four given ellipses, and a query ellipse. The article is restricted to non-intersecting ellipses, but the extension to arbitrary ones is possible. The ellipses are input in parametric representation, i.e. constructively in terms of their axes, center and rotation. For \ka and \kb we derive optimal algebraic conditions and provide efficient implementations in \cpp. For \kc we compute a tight bound on the number of complex tritangent circles and design an exact symbolic-numeric algorithm, which is implemented in \maple. This essentially answers \kd as well. We conclude with current work on optimizing \kc and on its implementation in \cpp.", }