基于投影变形大小的投影带和投影面选择

The Selection of Projection Zone and Plane is Based on the Size of Projection Distortion

我国国家坐标系统普遍采用高斯-克吕格正射投影(简称"高斯投影"),即先由地面投影到参考椭球面,再由参考椭球面投影到高斯平面。经过以上投影变换,定会引起一定的投影变形,变形的大小随投影点与大地水准面的距离不同而变化。针对该问题,工程测量中通常采用的处理方法是:a.采用任意分带形式,将中央子午线移至能控制投影变形的范围。b.根据实际需要,重新设定投影面高程。c.选定一个抵偿面。是先找到最佳中央子午线,然后计算抵偿面高程,得出最佳的投影带和投影面,通过实例计算对比,能得到最佳的投影带和投影面,在一定范围内,横坐标跨度最大,同时也能够准确的确定大地测量所需要的平面控制网的坐标系。

China’s national coordinate system commonly used Gauss-Kruger orthographic projections（ abbreviation ＂Gauss Projections＂）. That is to say the projections go first to the ground,and then to the reference ellipsoid. Next,the projections will finally projected onto the Gaussian flat. After the transform of above projections,it will cause some sort of deforms. The scale of the deforms will be varied with the different distance between the projection point and the geoid. Usually. Aimed at the problem,The approaches be used in engineering survey are： a. Use the form of zonation randomly to put the central meridian to the range that the projection distortion can be able to control; b. According to the actual needs,reset the elevation of projection plane; c. Select the compensation plane. In this paper,we should find the best central meridian at first,and then calculate the elevation of compensating surface,we will get the optimal projection zone and projection plane. By analysis of calculated result obtained the optimal projection zone and projection plane and the span of abscissa is the peak of maximum within a certain range,it also be able to accurately determine the coordinate system of the plane geodetic control network at the same time.