Local Geoid Method Based On Gps Leveling Data And The Earth Model

With the GPS (Global Positioning System) technology development and the increasingly mature, GPS relative positioning accuracy of elevation is up to (2-3) X 10-6,experimental results show that below the baseline for the 10km side length the accuracy can be achieved by a few centimeters In absolute precision, If the observation and calculation using a number of measures to eliminate errors, their accuracy is better than lcm.That geodetic height obtained with GPS positioning technology is converted to centimeter-level orthometric height or normal height has become an inevitable trend. Its implementation can reduce the workload outside the industry, save much of the material and financial resources, accelerate progress and improve work efficiency, leading to direct economic benefits. The prerequisite to achieve this goal is to have a sufficient accuracy Geoid and with geoid height or height anomaly, high-precision geodetic height will be able to convert to orthometric height or normal height we need. Determining the centimeter-level regional geoid is today's researching hot in geodesy, it will provide the necessary mapping services for based mapping, geo-spatial basic framework for digital china, regional subsidence monitoring, geological studies, transportation, water conservancy, electric power and other multi-disciplinary research and application.First, this paper introduces the purpose and meaning of Geoid Refinement, domestic and abroad geoid research status quo, Second, it systematically introduce the refinement of the regional geoid the principles and various methods, respectively, of which the gravity method and geometric method discussed in detail and study, in the gravity method, we study the main theoretical of using gravity method refining geoid: stokes theory and its several convolution form,molodensky theory,Geoid calculation model. in geometry, we mainly introduce and study the several fitting methods of GPS leveling, which includes fitting constant,polynomial interpolation,multi-faceted function method,mobile quadratic surface fitting,Shepard fitting,BP neural network simulation method. And then study the realization of two-dimensional FFT algorithm and its application in the refined geoid model.In chapter 4, using GPS/levels of data and fitting methods introduced in the two chapter which include fitting constant,polynomial interpolation,multi-faceted function method,mobile quadratic surface fitting,Shepard fitting,BP neural network simulation method. I use the Matlab language was fitting test and accuracy analysisConclusions indicate that fitting regional quasi-geoid can be applied to the conversion between geodetic height and normal height.in Chapter 5,we focuse on the Earth's gravity field model theory, the use of the Earth-bit models to determine the geoid height method and the use of the Earth's gravity field model and the GPS data to determine height anomaly method and Combined with the measured data of a survey area carried out a spreadsheet, draw some useful conclusions, finally, describes the comprehensive utilization of gravity data, terrain data, gravity field model and the GPS/level of the results of physical geodetic theory and method, application removal-recovery method to calculate gravity geoid, and then use GPS/quality control and calibration of gravity geoid systematic bias, the gravity geoid fitting on the GPS/standards to be measured quasi-geoid to obtain precise regional geoid, thus solving normal way.