The Comparative Study Of The Gravity Field Model And GPS /level Combination Method Of Regional Quasi Geoid Refinement

Boost the construction of Digital China and informationize surveying and mapping system is an extremely important work which can be achieved through launch of digital city construction, building the unification of urban geospatial framework and geospatial information public platform. City Regional quasi geoid is an urgent need for the construction of the digital city. Quasi geoid with high resolution and high accuracy not only guarantee the use of GPS direct determination of normal high but also greatly improve the surveying and mapping work efficiency and reduce the cost.In this paper, we firstly introduce the research background and the domestic and foreign like the development condition of the geoid, and domestic urban areas like the status quo of the geoid. Next geoid refinement principle and a variety of methods are well introduced. On this basis, we discuss about the earth’s gravity field model and egm2008 model. We calculate data selected in Shaanxi and briefly introduces the GPS data and the standard data acquisition, adjustment calculation and precision measurement. Respectively by quadratic polynomial, the polyhedral function, moving curved surface, the thin plate spline fitting method survey area quasi geoid, and compare the advantages and disadvantages of various fitting methods and some conclusions are obtained in this paper. Then the based on egm2008 earth gravity field model of the "remove recovery" method, survey area on geoid computation. In the end, a comparative analysis is making between the results and GPS Fitting Method, some meaningful conclusions are drawn.Finally the article sums up the work, puts forward several problems need to work in the future.