基于ICESat/GLAS高度计数据的SRTM数据精度评估——以青藏高原地区为例

Accuracy evaluation of SRTM data based on ICESat / GLAS altimeter data:A case study in the Tibetan Plateau

为全面了解航天飞机雷达测图计划(shuttle Radar topography mission,SRTM)高程数据的精度及误差特征,利用精度更高的ICESat/GLAS激光高度计数据(简称ICESat高度计数据)为参照数据,以具有多种地貌类型的中国青藏高原地区为实验区,采用双线性插值算法分析了SRTM在中国青藏高原地区的高程精度,以及SRTM高程数据与地形因子(坡度和坡向)间的关系。实验结果表明:在青藏高原地区,ICESat高度计数据与相对应的SRTM高程数据高度相关,相关系数高达0.999 8;SRTM的系统误差为2.36±16.48 m,中误差(RMSE)为16.65 m;当坡度低于25°时,SRTM高程数据精度随坡度增大而显著降低。此外,相对于ICESat高度计数据,SRTM在青藏高原地区N,NW和NE方向的测量值偏高,在S,SE和SW方向的测量值偏低。

To understand the accuracy and error characteristics of the shuttle Radar topography mission （ SRTM ） elevation data,the authors used the more precise ICESat/GLAS laser altimeter data as reference data in the Tibetan Plateau covering various landscape types so as to assess the accuracy of SRTM and explore the relationship between SRTM and terrain factors （ slope and aspect ） through bilinear interpolation algorithm. The experimental results show that ICESat altimeter data are highly correlated with SRTM data, with a correlation coefficient of 0. 999 8. The system error of SRTM is 2. 36 ± 16. 48 m,with a RMSE of 16. 65 m. The accuracy of SRTM data decreases obviously as the slope increases when the slope is lower than 25＆#176;. In addition, compared with ICESat altimeter data, the measurements of SRTM elevation are higher in the north, northwest and northeast directions, and lower in the south, southeast and southwest directions in the Tibetan Plateau.