Study On Elevation Fitting Method Based On EGM2008Model

Elevation obtained by GPS measurement is geodetic height that based on the WGS-84ellipsoid, and there is a. value between GPS geodetic height and normal height, which is named height anomaly. EGM2008is a new generation of Earth’s gravity field model, which is20cm providing the abnormal height of the overall accuracy in China mainland, which is12cm in the east and central regions, which is9cm in the northern region, which is24cm in the west region. The abnormal height provided by the model of the gravity field model has become a hot topic combined with a certain number GPS-level.The study analyzes the existing elevation fitting methods, explores and summarizes scope of application and accuracy after introducing the basic concept of elevation system and describing the basic theory. The study proposes the "removed-fitting-recovery" method based on the gravity model of EGM2008according to the deficiency of the traditional elevation conversion method. We can do elevation fitting researches through the method of combining the RBF neural network to GPS-level observation data. The test data prove that the accuracy can achieve3～4cm fitting precision using a few fitting points and the results are more reliable than other methods. The results can meet the needs of the majority of engineering measurement.