中文摘要：

研究利用重力场模型直接进行GPS高程转换的方法，即模型高程异常法和模型重力位法．根据误差传播定律，导出了由重力场模型位系数方差计算模型高程异常以及模型正常高的误差公式，并对影响两种GPS高程转换方法精度的因素进行分析．利用具有代表性的EGM96、EIGEN-51C和EGM2008重力场模型及某线路GPS／水准数据对两种方法进行实验研究与精度分析，结果表明：理论公式及实验结果都显示两种高程转换方法是等价的，转换精度相当；两种方法使用过程中，均可能需要系统偏差校正；EGM2008重力场模型具有非常好的分辨率及精度，在局部区域，基于EGM2008模型的GPS高程转换精度有望达到cm级．

英文摘要：

The methods of direct GPS height transformation based on Earth gravity field model are discussed in this paper. They include height anomaly method and gravity potential method. The error formulae of height anomaly and normal height are derived from the coefficient＇s variance of Earth gravity field based on error propagation rules, and the factors effecting on the GPS height transformation precision for two methods are analyzed. Based on the two methods, the test and accuracy analysis are carried out with GPS/leveling data and representative model EGM96, EIGEN-51C and EGM2008. The results show that the two transformation methods are equivalent from the theoretical formulae and test results; the systematic bias may be corrected during the GPS height transformation; the accuracy and resolution of EGM2008 model is higher than EGM96 and EIGEN-51C, in local region, the centimeter-level accuracy may be achieved for GPS height transformation with EGM2008.