基于三维椭球面电子矢量图的大地线表达新样式

A new style of geodesic line representation based on 3D ellipsoidal electronic vector map

传统海洋测绘成果与内陆专题地图一致,均采用“平面投影”的表达形式,无法避免投影变形,而多投影带间的相互搭接与转换在使用过程中又较为繁琐,为了规避海洋地区测绘成果的投影变形,借助克莱劳定理与Bessel大地主题解算方法,探讨了一种地理要素“椭球面三维电子矢量图”的表达形式,该地图以参考椭球面为地图绘制、地理要素表达的基准面,以大地线为基本线进行展绘。最后对两个案例进行了测试,测试结果表明:该大地线内插点位的解算成果是可靠的,大地线在绘制与表达上紧密依附参考椭球面,不存在投影过程,无投影变形,该样式更适用于海洋地理要素的表达。

The traditional marine surveying and mapping results are consistent with the inland thematic map,and both adopt the expression form of“plane projection”,which can not avoid projection deformation,and the overlapping and conversion between multiple projection zones are relatively complicated.In order to avoid the projection deformation of the marine surveying and mapping results,with the help of Clairaut equation and Bessel's geodetic thematic solution method,the expression form of a geographical element“Three-dimensional electronic ellipsoid vector map”is discussed,The map is drawn with reference ellipsoid as the reference plane of the geographical feature expression,and the geodesic as the basic line.Finally,two cases were tested,the test results show that the solution results of the geodesic interpolation points are correct.The geodesic is closely attached to the reference ellipsoid in drawing and expression,without projection process and projection deformation.This style is more suitable for the expression of marine geographical elements.