中文摘要：

对厘米级大地水准面精化中影响地形改正精度的几个因子：DEM精度、分辨率及积分半径进行了分析和评价。通过对地形质量影响的球谐展开分析，推导并量化了地形质量与DEM之间的线性关系，从而得到DEM精度至少需达到81m；综合分析DEM分辨率与球谐展开级数、积分半径之间的相互关系，给出适合厘米级大地水准面精化的分辨率和积分半径。以我国地表起伏较大的西藏某区为研究区域，选取不同分辨率DEM、不同积分半径，并利用SRTM计算地形影响。结果表明，6”分辨率的DEM和50’的积分半径可以满足大地水准面的厘米级精度要求。

英文摘要：

There＇re several factors affecting the accuracy of terrain correction to obtain geoid with centimeter-level ： accu- racy of DEM, resolution and the integral radius. Derive the linear relationship between DEM and terrain correction by computing the spherical harmonic expansions. The resuh showed that the accuracy of DEM should be better than 81m. After the relationship between resolution and the degree of spherical harmonic expansions and integral radiusanalyzed, the best suitable factors for geoid with centimeter-level was giant.This article chosed different resolution and different in- tegral radius to compute terrain correction with DEM of Tibet. The test results showed that the resolution of 6＂ DEM could meet the needs of geoid with centimeter-level. And it needs 50＇ integral radius to meet the corresponding requirements.