Research On Replaccement Of Leveling Surveying By GPS Elevation Fitting

GPS is the technology of radio navigation and localization which takes the satellite as the foundation and emerges along with the modem science development, it can provide three dimensional coordinates of space point, the speed of surveying object and the time for each kind of user,h recent years. along with the technical rapid development as well as the American Government SA policy graduallycancellation and appearing of a series of measure method, fartherly with the improve of the navigation localization technology of GPS in precision,reliability and stability, it has more and more widespread application in ours daily life.However,GPS also has its deficiency in the elevation pointing accuracy aspect,Because the geoid is an irregular curved surface, it is unable with an essence accurate curved surface to simulate,this enables GPS only to provide for US the accuracy of the geoid height,but is not the normal height in our project needs. So it has seriously affected the three dimensional localization application development of GPS and makes the superiority of providing the three dimensional coordinates not to be able to obtain the full display.This article introduced GPS principle of work as well as the concept of the GPS geoid height,normal height and orthometric height and three mutual relations, elaborated the principle of GPS standard(GPs elevation fitting), in the collection the consult,has analyzed in the last few years domestic and foreign in view of the GPS standard high research technique and the application technology.After the collection,consult,and analysing in the last few years dome-stic and foreign in view of the GPS standard height research technique and the application technology,and in the foundations of these research results, Aming at the slightly hilly terrain as the trait of Southwest,and using existing GPS obversed data from Shaoyang urban2nd cadastre investigation and control survery and geometrical standard materials as known data, I undertook the GPS height fitting, taking advantage of quadric surface and multiple-surface function methods. Through comprehensive comparation and analytical research in experiments, I came up with accuracy evaluation using the different fitting methods to the same terrain and suggest concrete conclusion and advice. The identification of the fitting results illustrated: under certain conditions, we gain high accurate surface coordinates and geodetic height using GPS, the results of the weighted averages method fitting can not met the demand in plain leveling survey, the results of multiple-surface functions fitting met the demand in four class leveling survey, so this means can completely replace conventional geometrical leveling survey; quadric surface fitting needs to judge according to elevation abnormality charts, and we should exert divisional fitting methods in areas with no more than one hilly surfaces, and the results from it content the accurate demand of plain leveling survey, which is of great directive significance to engineering elevation survey.