RESEARCH ON ACCURACY OF QUASI-GEOID WITH FITTING METHODS UNDER DIFFERENT DISTRIBUTION OF GPS POINTS
拟合点分布与GPS水准面拟合精度关系研究

The aim of this study is to find out the relation between density of GPS leveling points and interpolation error,and to provide scientific basis for planning GPS leveling network and three following chief contents are given.(1) The GPS leveling points are divided into two groups,one is called fitting points that are used to fitting guasi-geoid,and those in another group are called check points that are used to check the interpolation error.(2) Using four fitting methods with six parameters,Multi-curve function,Moving curve and fitting element method to fit the local quasi-geoid and the fitting accuracy will be evaluated with the check points.(3) Through the calculation and analysis,the anwsers are:a) The accuracy of local quasi-geoid is higher than 2 centimetre with practical third grade leveling combining with GPS;b)Interpolated nomal height can take place of fourth grade leveling when GPS density resolutions are 1 000 meter,1 250 meter and1 500 meter;c)When the resolution is 2 000 meters,the interpolation nomal height can take place of fourth grade leveling only by use of finite the limted element method.