等分分层组合投影研究

针对中国地理格网(1°、10°等多级格网系统)的分割方法,设计了一种适合该格网系统的新型地图投影——分层组合投影。从微分几何的观点出发,把地球椭球按等纬度分割成若干层圆台,分别建立每个圆台的投影模型,即可得到一种地图投影。这种投影还可根据格网间隔的不同进行细分,从而发展成为一种适合多分辨率格网模型的动态地图投影。通过对该投影进行变形计算表明,该投影可以保持等角,而且面积和长度变形都很小,特别是在高纬度地区,与Mercator投影相比变形明显减小。

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.