AN ANALYTICAL APPROACH TO THE DISTORTION CHARACTERISTICS OF GINZBURG’S POLYCONIC PROJECTONS

I.O. Bildirici¹, C. Ipbuker²

1 - Selcuk University Engineering Faculty, Dept of Geodesy & Photogrammetry, Konya, Turkey

2 - Istanbul Technical University, Civil Eng.Faculty, Geodesy & Photogrammetry Eng. Dept. 34469 Maslak, Istanbul, Turkey

iobildirici@yahoo.com

Some map projections are defined by table values rather than mathematical equations. The most popular and famous one in this category is the Robinson Projection. The Ginzburg projections, which were developed and used in the former Soviet Union, are also defined with tabular coordinates. But, the mathematical model of polyconic ones between them is actually known. In a previous work, the authors discussed the forward and inverse transformation of them, and suggested different numerical approaches with the partial derivatives required for distortion analysis. In this paper, first the mathematical model of the policonic projections of Ginzburg is given, and then the distortion characteristics of Ginzburg IV, V, VI and 1966 are discussed in detail. They are arbitrary in distortion distribution, neither conformal nor equal-area, but they show very reasonable distortions. Considering distortion characteristics Ginzburg projections are also compared with two popular world projections with optimal distortion distribution: Winkel Tripel and Robinson Projections. With the awareness of such projections, there are more alternatives in seeking a suitable map projection in world-scale GIS implementations.