The Establishment of Engineering Coordinate System and Its Coordinate Transformation by Changing the Geometric Parameters of Ellipsoid

We often encounter the problem of mutual transformation between the various coordinate expression in the work. because the engineering ellipsoid is only for the country long ellipsoid half shaft made of change, and the two centre, flattening the same, so their space rectangular coordinate system of the three axis also overlap, namely national ellipsoid space rectangular coordinate with engineering ellipsoid space rectangular coordinate exactly equal. Based on this, this paper introduces some key factors that need to be considered in establishing engineering coordinate system by changing the geometric parameters of ellipsoid. The idea of transforming engineering coordinates, national coordinates and urban coordinates based on different ellipsoid parameters is put forward. It provides useful reference for the practice of surveying and mapping engineering.