A New Method of Map Projection to Decrease Projection Distortion

This paper presents a new map projection based on the new form of geodetic coordinate system.In mathematics,an ellipsoidal surface can be approximated by a series of continuous secant facets,each of which passes through four corner points of corresponding grid formed by two geodetic parallels and two meridians and is taken as mapping plane.Based on this idea,a sphenoid projection mode which takes the points on the minor axis of ellipsoid as its projection centers is brought forward.Herein the points on ellipsoid and their relevant projection centers have the same latitudes.The variations of scale can be smaller than those in a usual map projection,but the new projection mode can still keep the continuity between two adjacent map sheets.The theoretical research and data testing for this method are carried out in this paper.