Research And Realization Of Coordinate Conversion System

Because of some historical factors,different countries and regions differ in their adoption of the reference ellipsoid,and as a result,there appear a variety of geodetic coordinate systems.Even in the same country or district,the geodetic coordinate system of different historical periods may have differences.At present,China takes the geodetic control point which uses Beijing 54 coordinate system or Xi'an 80 coordinate system in mapping,engineering design,engineering planning and other usage.How to convert the existing measurement data between Beijing 54 coordinate system,Xi'an 80 coordinate system and local independent coordinate system,and finally convert to Chinese geodetic Coordinate System 2000 is an urgent problem to be solved to realize Geospatial information sharing,the avoidance of repeated construction and reduction of resource waste.Research of the conversion relationship between different coordinated systems and the analysis of the influential factors,in order to make the high precision conversion between different coordinate systems come true and assure that the surveying and mapping results can be accurately switched to be used in the objective coordinate system and make use of the obtained surveying and mapping results and data to a large extent.The main work of this thesis is as follows:(1)Based on the fundamental theory of Earth ellipsoid,the coordinate system is simply classified,and this thesis introduces the coordinate system commonly used in China and narrates the methods of how to convert between different coordinate systems.(2)As for the problem of the non-uniform coordinate systems in local places and projects,this thesis researches the influence of the common points on the precision of coordinate conversion.By way of researching some effective factors,the project case study of the influence of several factors such as the number of common points,the common point distribution and the common point precision on the accuracy of coordinate transformation.(3)This thesis lays great importance on the study of two models of the conversion of WGS-84 coordinate to the commonly used reference-ellipsoid-centric coordinate system in China,namely,Plane transformation model and Space transformation model.In addition,the conversion between these two transformation models is testified by use of the actual data.(4)On this basis,this thesis designs a set of coordinate system conversion software to realize the conversion between different coordinate systems.Taking Yulin City as an example,this thesis designs the conversion between Local independent coordinate system in Yulin City and Beijing 54 Coordinate system and Xi'an 80 coordinate system.The design of the software is succinct,friendly and easy to operate.