
Journal for Geometry and Graphics 08 (2004), No. 2, 215224 Copyright Heldermann Verlag 2004 On Arne Dür's Equation Concerning Central Axonometries Hellmuth Stachel Institute of Discrete Mathematics and Geometry, Vienna University of Technology, Wiedner Hauptstr. 810/104, 1040 Vienna, Austria stachel@dmg.tuwien.ac.at It is a classical Descriptive Geometry problem in the Euclidean nspace to characterize the central projections among collinear transformations with rank deficiency. Recently A. Dür [Journal for Geometry and Graphics 7 (2003) 137143] presented for n = 3 a characterization in form of an equation in complex coordinates  the central axonometric counterpart of the Gauss equation for orthogonal axonometries. Here two new proofs for Dür's equation are given combined with equivalent statements. And its ndimensional generalization is addressed which characterizes twodimensional orthogonal central views among central axonometries. Keywords: Central projection, central axonometry. MSC: 51N05 [ Fulltextpdf (162 KB)] for subscribers only. 