THE USE OF GEOGRAPHIC AND MAP GRID COORDINATE SYSTEMS FOR GEODETIC NETWORK ADJUSTMENTS

Abstract

Geodetic networks composed of conventional survey measurements may be based upon different types of coordinate systems. The most commonly used are geographic coordinates of latitude, longitude and height, or map grid coordinates of easting, northing and height. The adjustment of such networks may be similarly based upon either of these coordinate systems and the well accepted principles of least squares estimation and variation of coordinates. The observation equations required for the map grid and geographical coordinate system are presented, along with the necessary differential coefficients which make up the design matrices for the adjustments. As well as the traditional survey measurements, the observation equations and differentials required for Global Positioning System (GPS) baselines are included for each coordinate system. A comparison is made between the convenience, accuracy and efficiency of each approach. Results are presented of the adjustment of example networks composed of simulated and real data. Some conclusions are drawn regarding the appropriate use of the two different approaches for geodetic network adjustments.