椭球膨胀法在线路工程坐标系建立中的应用

Application of Ellipsoid Expansion Method in the Establishment of Linear Engineering Coordinate System

【目的】运用椭球膨胀法,建立线路工程坐标系,减小因测区跨度大、海拔高、起伏大引起的投影变形。【方法】研究5种椭球膨胀方法的原理,并结合实例从长半轴变化量、基点大地坐标变化量、边长变形量等3个方面进行计算分析。【结果】5种椭球膨胀方法的严密程度不同,得到的计算结果也不同,通过直接法、卯酉曲率半径法、平均曲率半径法计算得到的结果差异较大,通过平面解析法、广义微分法计算得到的结果差异最小,且投影变形量均能满足要求。【结论】5种椭球膨胀方法均可用于线路工程坐标系的建立。

[Purposes]This paper applies ellipsoid expansion method to establish the coordinate system of line engineering,and reduce the projection deformation caused by large span,high elevation,and high undulation in the survey area.[Methods]The principles of five ellipsoid expansion methods are dis⁃cussed,and the calculation and analysis are carried out from three aspects,namely,the amount of change in the long semi-axis,the amount of change in the geodetic coordinates of the base point,and the amount of deformation of the side length combing with examples.[Findings]The five ellipsoidal expansion meth⁃ods have different degree of rigour and the calculation results obtained are different,the results obtained by direct method,prime unitary curvature radius method and mean radius of curvature method have large differences,and the results obtained by planar analytic method and generalized differential method have the smallest differences,and the projection deformation amount can satisfy the requirements.[Conclu⁃sions]All five ellipsoid expansion methods can be used for the establishment of line engineering coordi⁃nate system.