The Research Of GPS Elevation Application In Municipal Engineering

The plane coordinates and ellipsoidal height of GPS provide, which are highly accuracy and stability, can meet the production needs.But in the real engineering, we need the normal height which equals the ellipsoidal height minus height anomaly.So the precision of height anormaly directly affects the GPS height precision. We should improve the precision of GPS height abnormally to get GPS height of high precision.This paper, studies12kinds of GPS height anomaly fitting model, including linear model and planar model.The former includes line fitting, polynomial curve fitting, MLS curve fitting and orthogonal function fitting, spline fitting and AKIMA curve fitting.The latter includes plane fitting, moving curved surface fitting, chebyshev polynomial fitting, MLS curved surface fitting, moving curved surface fitting and the polyhedral function fitting. For ease of use, the GANHIS is developed with all the fitting models above.Theoretical analysis and numerical examples,we find that the height abnormally precision is affected by the amount of modeling datas, data distribution, datas’precision and so on. The amount of Modeling datas should increase2more or less except meeting the number of coefficients to solve.The distribution of modeling point should be uniform global as far as possible;The precision of modeling datas have a direct impact on the fitting accuracy.we should cancel the error datas before fitting.This paper studies GPS height which comes from CORS-RTK,GPS static and conventional GPS-RTK.It can meet Fourth-order accuracy with proper condition. This suggests that in good condition, the GPS elevation can basically meet the need of municipal engineering.