A GPS height transformation method by Remove-Restore idea,using EIGEN-GL04C EGM,local topographic correction and geometry method is presented in this paper.It verified the precision of EIGEN-GL04C EGM and compared some formulae of current local topographic correction.Besides,a case study of tunnel project is given to show that the proposed method is useful and effective.The algorithm is also proved to get good precision in mountain area of rugged topography.

For the low precision of GPS height transformation by simple numerical approach in areas of rugged topography,a GPS height transform method,based on remove-polish-restore idea,combining EIGEN-CG03C EGM and numerical approach is presented,Finally,a tunnel example shows that the proposed method is effective and practical,and algorithm proves a satisfying precision in mountains of rugged topography.