DEM分辨率对计算地形起伏引起的高程异常的影响

影响GPS高程转换精度主要有两个方面：地形改正的短波段分量和重力场改正的中长波段分量。文章以四川某山区为例，采用不同分辨率的数字高程模型（DEM）来计算各控制点的高程异常地形改正值，然后利用“移去-恢复”技术来拟合各控制点的高程异常值。结果表明，对于山区当DEM分辨率在10m～100m内取20m-30m时，可以显著提高GPS高程转换的精度，从而有利于具有精度高、速度快、布网灵活等诸多优势的GPS高程测量新技术的普及应用。

The Impact of DEM Resolution on the Calculation of Height Anomaly Caused by Hypsography

There are mainly two aspects affecting the GPS height conversion Accuracy： the short-wave component of topographic correction and the medium-and long-band component of gravitational field. This paper calculates the elevation unusual values of control points with different resolution DEM data of digital elevation models （DEM） of a mountain area of Sichuan. Then use the ＂remove - to resume＂ technology to fit the elevation unusual values of control points. The results obtain that taking 20 m- 30 m when the DEM resolution in the 10 m - 100 m can significantly improve the accuracy of GPS height conversion. It is advantage for the wider application of new technologies of GPS height measurement which has high precision, quickly speed, net flexible cloth and many other advantages.