Study On The Methods Of Refining The Quasi-geoid Based On GGMplus Model

Quasi geoid refinement is a process for determining exact height anomaly. It is also one of the key technologies in simultaneously obtain true 3D coordinates of ground point. A high-resolution and accurate quasi-geoid model can effectively reduce leveling workload and improve work efficiency. For this purpose, finding an accuracy and high-resolution quasi-geoid model has become a hot topic.Firstly, this paper introduced the concept and necessity of quasi geoid refinement. Through domestic and foreign-related research, described the quasi geoid model and technical progress in chapter one. Besides, the latest research results of foreign countries were also given. The geoid refinement theory, remove restore method and two commonly used fitting algorithms were discussed in chapter two.Secondly, we researched GGMplus model which had new ultra-high resolution picture of Earth’s gravity field. The model used three kinds of data and six steps to obtain five gravity field messages. Difference between this model and other models could make us better use this model. According to MATLAB platform and model application methods, this paper analyzd its mass data storage technology and compiled a new program which would dedicate to processing the geoid refinement data. Through analyzing experimental results and researching relation between EGM08 and GGMplus in many regions, we built a combined model called joint model.Finally, according to data and methods which were used in EGM08 model and GGMplus model, this paper caught principal of joint model. Because the principal combined long time satellite data, the joint model could have more reliable accuracy. Based on remove restore geoid refinement software and many accuracy assessment factors, the paper got a conclusion that the joint model was better than EGM08 model and GGMplus model, especially in mountain area.