Accuracy Evaluation Of Regional Quasi-geoid Refinement

In recent years, with the continuous development of satellite positioning technology, Global Positioning System(GPS) has been extensive applied in the field of surveying and mapping. In order to obtain high-precision point flat position at the same time, also be able to obtain high-precision of elevation data,determine the high-precision Quasi-Geoid has become a necessary work. Not only does it play on the basis of surveying and mapping the advantage, but also for the geoscientific research, marine science, regional subsidence monitoring as well as transportation and water conservancy and other services to provide the necessary mapping services. Determination using GPS to determine the normal-height, can greatly save manpower and expenditure, improve operating efficiency.This paper first introduces the research background and the development present situation in domestic and abroad of the regional quasi-geoid, systematic exposition of the principles of refined quasi-geoid and various of methods to conventional GPS/standard geometrical fitting divided into functional model, statistical model and integrated model. The paper respectively introduces the principle, the elaboration and analysis of their respective features and applicable scope are compared.In order to be able to accurately compare several common fitting precision of the models, Based on the research of the inner precision and the outer precision, root-mean-square-error(RMSE) in height-anomaly used as auxiliary accuracy index to assess the precision of the model fitting results. RMSE in height-anomaly can better reflect to the fitting precision of each point, as a standard to judge the level of high and low precision. Established the mathematical model reflect elevation fitting precision without area constraint conditions extreme value point, and by interpolation with the area of the constraint method, look for local extreme value point of the precision of experiment was carried out.In this article, through the trial case of RMSE in height-anomaly index for feasibility analysis, then combined with the relevant information of a concrete actual project, according to the characteristics of the terrain, combining with the actual situation of area measuring point distribution, respectively based on the fitting point number, location, fitting method, weight distribution, partition fitting scheme is comparative analyzed, plentiful available experience and conclusion, for the future plans of regional 1uasi-geoid refinement and its precision-assessment provides a theoretical basis.