Study On Solving GPS Elevation Anomalies By Using Entropy Function Model

Global Positioning System is widely used in Surveying Engineering due to its advantages.GPS measurement can obtain high-precision geodetic height,but the general elevation system in the project is normally high.Leveling Surveying is the traditional method of obtaining the normal height.There is a difference between geodetic height and normal height,which is called height anomaly,that is H=h+?,where H is the geodetic height,h is the normally height,and?is the height anomaly.Therefore,it is particularly important to determine the height anomaly in practical engineering applications.GPS measurement is not only widely used in practice,but also more and more in our daily life.If GPS measurements are fully utilized,GPS measurements can better serve actual production or daily life,that's why people pay more attention to the research of elevation abnormality,and use the land effectively.Although the number of method to obtaining elevation anomaly is not too small,because of the harsh conditions,there are not many methods to obtain the elevation anomaly in actual work.GPS elevation fitting is one of the low condition ways,and this method can obtain.In this paper,we introduces the conversion principle of GPS elevation briefly at first,and introduce several conversion methods of GPS height anomaly.Then,several GPS height anomaly fitting models and methods that are used commonly are listed,the applicable regions and actual situation of these methods are described.Based on the above,the theory of maximum entropy is introduced,and the maximum entropy method can be used to fit the GPS height anomaly.It is discussed that the maximum entropy method can make the data model maximum dependence on the sample,that is,the model error minimization,which makes the interpolation model more able to reflect the discreteness of the spatial data,the model will be more robust.Finally,according to the above theoretical knowledge,combined with relevant examples,several commonly used fitting methods and maximum entropy methods are used,the test results are evaluated respectively.Through the comparison and analysis of the fitting results,the established model is proved to be reliable and the fitting accuracy is well,which shows that the maximum entropy method is of great significance for the research of GPS elevation fitting.