Study On The Local Quasi - Fine Refined Area Of ​​Local Area By Partition Method

Geoid(quasi-geoid) represents reference plane of the earth’s shape reflects distribution of the earth’s interior quality, and it’s also the elevation datum plane of the Leveling field at same time. Therefore, the establishment of high-precision and high-resolution local geoid model not only provides basic geospatial information for geodetic surveying, geodynamics,geophysics and other disciplines, but also offers essential information for realization of digital earth and digital China. At present, confirming Local or regional quasi-geoid of cm-level’s precision is hot spot of Geodesy research. Geoid(quasi-geoid) will supply necessary substantive services for digital China spatial basic framework, basic surveying and mapping, regional settlement observations, geological and seismic studies, defence constructions, and researches and applications of other disciplines. Thence, the construction of appropriate geoid has special important scientific significance and enormous social and economic benefits.The thesis has systematically studied theories of various geoid refinement methods, respectively discussed and researched advantages and disadvantages of each of these methods in detail. It has described some geometric methods for fitting method in detail, analyzed their respective applications, and also described the basic principles and processes of the two combination methods. In the small wavy terrain, we can directly apply geometric method to refine geoid (quasi-geoid),while If we select a larger area and the terrains are undulating(hills and mountains), it’s difficult to meet the requirements if we use this method to fit geoid. On the other hand, it’s difficult to gain the gravity data of these areas, it leads to the resolution of gravity data are very low. For this case, the thesis has proposed to apply zoning approach which could better achieve the regional geoid refinement. Some areas(relatively flat)could refine geoid without gravity data, namely use EGM2008gravity field model combining GPS or leveling data to fit geoid directly, so as to meeting the requirement and achieve a more cost-effective purpose. Other areas could utilize gravity combination method to fit geoid if we have enough gravity data. If the lack of gravity data, we could use zoning approach to fit geoid respectively, the last chapter has described to use zoning approach to control the overall accuracy in this case. Using data of parts of Yunnan province to test and verify, found that the approach is feasible.