Fitting Method Geiod Refinement In The Application Of Relatively

Geiod or quasi-geoid is a height datum for acquiring geospatial information. If the geoid or quasi-geoid model is given, GPS can be used directly to determine orthometric height or normal height, which can take the place of the traditional geometric leveling and make the seperation mode of plane control network and elevation control network in traditional geodesy become a history. Therefore geoid refining is one of important missions for the establishment of the height datum in a country or a region.Precise determination of local geoid is the importing issue of some field .such asgeodesy and geophysical .and so on. And same time, it also is a import project of basemap up date, Regional geoid determination with centimeter-level precision is the geodesy research hotspot. It will provide mufti-disciplinary research and application such as base map up date ,digital China geo-spatial framework, local monitoring on settlement ,environment forecast ,disaster prevention, national defense construction,ocean science, weather forecast, earth science research, traffic, water resources,power with essential surveying and mapping service, has significant scientific significance and tremendous economic and social benefit.At first the article describes basic theory and principles of precise determination of local geoid. Then discuss and make a research about geometrical method and gravitymethod at length, respectively. In the geometrical method ,compute and analyze the applicable area of the moving curved surface fitting, multiple curved surface fitting, Neural Network (NNT) ,compare the precision and applicable area.Combining measuring region GPS/leveling data thesis adopts the maul trinomial surface:fitting model and move curve surface fitting model and Har function interpolation model, author has developed a MATLAB program to do the test and analyze its accuracy and draws several satisfied conclusion's. The fitting regional quasi-gieod can be applied into the shift between GPS height and normal height. Then, it introduces the theory of global geopotential model and studies how to determine regional quasi-geoid with remove-restore method, GPS/leveling data and global geopotential model, gaining the; normal height.