The Research On Transformation Results Of Geodesy Control Between China Geodetic Coordinate System 2000 And Ordinary Coordinate Systemin China

Since the foundation of our country, we have established 1954 Beijing coordinatessystem and 1980 Xi`an coordinates system. They have provided the basic mapping guara nteeto nationa l economic and socia l development, and made tremendous contributions to thedevelopment of surveying and mapping enterprise. But they all belong to reference centriccoordinate system, there are a series of deficienc ies and shortcomings during the process ofusing. They have been unable to meet the requirements of mapping and related industries inChina, economic construction and nationa l defense construction and socia l development.Under this background, on July1, 2008, we officia lly opened the new geocentric coordinatesystem-China Geodetic Coordinate System 2000. It would be an urgent and mea ningful issueon how to effectively use the origina l mapping results and information, to establish the linksbetween the old and new coordinate system, and to study the influencing factors betweenthem.This article describes the related theoretica l knowledge of coordinate system, expla insthe circumsta nces about the coordinate system which we are using and China GeodeticCoordinate System 2000 in details. There are two aspects refered to coordinate transformation ,the transformation under the same datum and different datum. This paper ma inly studies thetransformation under different datum. The transformation can be carried out in three ways:First, using the common point to solve the transform paramete rs between the two sets ofcoordinate system and then to achieve transformation. The scope of nationa l and provincia llevel coordinate transformation choose the transformation model of two dimensiona l sevenparameters, while the scope below provincia l level select three dimensiona l four parametersmodel or two dimensiona l four parameters. For the relatively independent pla ne coordinate system, it does not need to convert to China Geodetic Coordinate System 2000, but mustestablish the linkages with the China Geodetic Coordinate System 2000. we can use 1980Xi`an coordinates system or 1954 Beijing coordinates system as transitions to set contact withChina Geodetic Coordinate System 2000; Second , by using the constrained adjustmentmethod from the contrast between a high grade-point joint China Geodetic Coordinate System2000 measuring and a low-grade GPS nets to achieve conversion; Third, change the pointposition of Internationa l Terrestrial Reference Frame to China Geodetic Coordinate System2000 through the framework of conversion and mea n conversion.This paper focuses on the first method. Based on the author's own designed program,combined with the anlysis of examples, we get the flowing achievements:First, in differentregions in China, with the same transformation model, we can get the different transformparameters. Second, changing 1954 Beijing coordinates system and 1980 Xi`an coordinatessystem into China Geodetic Coordinate System 2000, compared with seven parameterstransformation, four parameters transformation has a higher accuracy, but in the central part ofChina , their differences about accuracy turn out little. Third, as for the select ion of publicpoints, they should be selected well-proportioned in the transformation region, the moreextensively the public points distribute, the higher conversion accuracy we get. Too much ortoo little single points can not increase the conversion accuracy. Fourth, no matter using fourparameters transformation or seven parameters transformation, the accuracy from 1980 Xi`ancoordinates system into China Geodetic Coordinate System 2000 is higher tha n that from1954 Beijing coordinates system into China Geodetic Coordinate System 2000. Fifth, amongall the transformation parameters, the translation parameters influence the most, while therotation parameters second, and scale parameters the sma llest, but the scale parameters can notbe ignored.