大地高误差对坐标系转换精度的影响

摘要

3D coordinates for ground points can be directly obtained in the satellite geodesy,which successfully solves the problem of plane and elevation separatly building a network in traditional work.However,the obtained 3-D coordinates based on the global geodetic coordinate frame (WGS84 or the IRTF),can not be directly applied to practical engineering projects,so the coordinate system conversion from will be needed the ellipsoid transform.The access to the geodetic height based on local coordinate frame (local ellipsoid) is difficult and the ellipsoid transformation parameters can only be approximated.The geodetic height error on the accuracy of the coordinate system conversion is analysed in which,through examples that the influnce is negligible in the local area.%卫星大地测量直接获取地面点的三维坐标,解决了传统作业中平面和高程分开建网的问题.但获得的三维坐标基于全球大地坐标框架(WGS84或IRTF),不能直接应用于实际的工程项目中,需要通过椭球变换实现坐标系转换.由于基于本地坐标框架(局部椭球)的大地高较难得到,椭球变换参数只能近似求得.分析大地高误差对坐标系转换精度的影响,并用实例证实此影响在局部范围内是可以忽略的.