Study And Application Of GPS Height Transformation Based On SST Earth Gravity Model

As the appearance of GPS has great impact to the conventional technology surveying, geometry leveling has no exception. First of all, even on the precision, the challenge of GPS is obvious in efficiency, economy, real-time character. If normal height is not necessary for some cases, GPS leveling can replace geometry leveling to solve the problems of engineering or scientific research. Secondly, if the abnormal height has been computed by quasi-geoid, geodetic height computed from GPS surveying can been translated into normal height. The method is an alternative for leveling.With the gravity of the development of satellite technology, in particular a series of high-precision satellite tracking satellite (satellite-to-satellite tracking, SST) Earth Gravity Model for the development of GPS height transformation provides a good reference datum, such as the recent release of high-precision Earth Gravity Model of EGM2008, the order of 2190 to meet bands, spatial resolution of about 9km.However, the GPS measurement of geodetic height into a normal high there are still a number of ways and many of the preferred Earth Gravity Model optimization problem. This paper is aimed at the content of these two areas have done a more detailed discussion and analysis.This thesis introduced the basic theory of GPS height transformation, which introduced a number of conventional pure mathematical functions fitting the height of GPS, and describes only the use of SST Earth Gravity Model on the basic principles of GPS height transformation. In introducing the Earth Gravity Model, the European large-scale regional and a specific tunnel project for an example, do a lot of comparative analysis of Earth Gravity Model. Gravi- tational methods and Numerical Fitting methods, In view of the merits and demerits of them are complementary for each other, According to the fact that the precision of GPS height transformation is low by simple geometry method in areas of rugged topography, a GPS height transform method by Remove-Interpolate-Restore idea with EGM,local topographic correction and geometry method is presented, and light of the specific example of a tunnel project are analyzed and compared the accuracy of various methods and applicability of the GPS height transformation. Uniform distribution of known GPS /Level points in the circumstances, evidence of the high mountain, the accuracy of the integrated algorithm is superior to other methods, Demonstrated in the mountains known GPS/Level points, under the circumstances of uneven distribution ,using the method of high-precision Earth Gravity Model EGM2008 combine system deviation correction , the accuracy is superior to other methods.