在AutoCAD中参考椭球面上大地线及DLG表达新方法

A New Method for Expression of Geodesic Lines and DLG on the Reference Ellipsoid in AutoCAD

基于大地线与克莱劳方程的特性,完成了大地线内插点的大地坐标解算及其空间直角坐标的转换,并借助AutoCAD三维模拟空间构建了参考椭球,实现了大地线与大区域三维面状要素在参考椭球面上的绘制与表达,探讨了大地线的解算与表达精度。最后通过实例表明:该三维DLG在较大地理区域线状、面状要素的表达中,避免了投影变形,且具有精确可量测性,为今后可精确量测的三维DLG的制作与发展提供了一些值得借鉴的经验。

This paper completes the geodetic coordinate calculation of the interpolated point and the transformation of the spatial Cartesian coordinates based on the characteristics of geodesic line and Clairau equations. The reference ellipsoid is constructed with the help of AutoCAD 3D simulation space, which achieves the drawing and expression of geodesic line and large area 3D polygon on the surface of reference ellipsoid, and discusses the solution and expression accuracy of geodesic line. Finally, two examples are shown that： the 3D expression of DLG avoids the projection deformation in the expression of linear and surface elements in a large geographic area, and has precise and measureable properties. It provides a valuable experiences for making and developing on 3D DLG in the future .