Research on the Combined Projection Based on the Method of Average Stratified of the Earth

A kind of new map projection,called multi-level combined projection,was designed in this paper,which was suitable for the geographic grid system of China.It was also the hierarchy grid system partitioned by the latitude1°,10°,et al.The basic idea here was to divide the ellipsoid averagely to some level along with latitude according to the theory of differential geometry,and then to establish the projection model for each level.Therefore a new kind map projection was obtained.This kind of map projection could be subdivision according to the different grid scale,and could be developed to a kind of dynamic map projection which was appropriated for multi-resolution grid model.It is show by the distortion computation that the map projection is conformal,and the area distortion and length distortion is also small.Especially in the high latitude area,the distortions are apparently decreased comparing with Mercator projection.