地图投影的分类,常见的主要有两种划分标志,一是依据投影后表象的不变性(或即变形性质),二是按正常位置下经纬线的形状来区分。前者是属于内在的问题,后者是属于外在的问题。

Through analyzing the invariants in map projection and according to the condi-tions whether there are any directions along which length of segements is true, the author finds that the projections can be mainly divided into three categories, i.e., elliptic, parabolic and hyperbolic. A new way of studying map projection has been derived and the problems remained in Prof. Wu's monograph "mathematic carto-graphy" (1964, in Chinese) are solved.