Simple Discussion on Electronic Map Coordinates Transformation in ITS for Small and Medium Cities
LU Liang-xi · Geomatics & Spatial Information Technology · 2004
Most electronic maps in ITS are based on Beijing 54 coordinates, Xi'an80 coordinates or local coordinates system. The outcome of GPS dynamic positioning is based on WGS-84 coordinates system. Therefore some coordinates transformation must be constructed in order that the outcome of WGS-84 can be directly showed on electronic map in real time. The precision of GPS dynamic positioning is up to 10 meters since SA was abolished in 2000. Firstly this paper introduces some characters of constructing ITS in small and medium cities and the simplified transformation formula from WGS-84 coordinates system to electronic map coordinates is built. This method saves some calculating time and declines the demand for software and hardware in ITS. Based on it, a practical and cheap ITS can be built in middle cities. Finally an experiment test is feasible.