关键词: 中国大陆区域, TanDEM-X 90 m DEM, ICESat/GLA14, 误差, 影响因素, 分布规律, 保真性

Abstract:

Some topographic factors such as slope, aspect, and land cover may cause errors on TanDEM-X 90 m Digital Elevation Model (DEM) product when collecting and processing of these data. In order to better understand the error distribution and serve the research in this field, the comparison between TanDEM-X 90 m DEM and ICESat/GLA14 DEM was conducted over the entire China. The findings are summarized: ① The average absolute error, Root Mean Square Error (RMSE) and Standard Deviation (STD) of TanDEM-X 90 m DEM over the entire China are about 3.89, 9.03, and 8.85 m, respectively. ② The error increases when the slope increases. The mean absolute error is about 1.29 m and the STD is about 2.84 m when the slope is below 3°. In comparison, the mean absolute error is above 20 m and the STD is about 30 m when the slope is above 25°. ③ For the aspect, the mean value of absolute error in the north-south direction is obviously smaller than that in the east-west direction, indicating the influence of aspect on TanDEM-X 90 m DEM product. ④ For the land cover, the uncultivated land shows the smallest error with the mean absolute error of 1.85 m, while the region covered with snow and glacier show the largest error with the mean absolute error of 12.68 m. Comparisons of the contour map and profile between TanDEM-X 90 m DEM and UAV-derived DEM suggest that the TanDEM-X 90 m DEM can reflect the real topography. However, due to the influence of resolution in some areas, it can not be expressed for some detailed terrains, especially for valley and ridge. The absolute error distribution of TanDEM-X 90 m DEM over the entire China is produced and evaluated based the weights of different influencing factors, which are considered to be reliable. Through the analysis of error distribution map, it is found that the accuracy of TanDEM-X 90 m DEM shows a trend of high in the north and low in the South over the entire mainland of China. In the North China region, the overall accuracy is higher, while the error in the northwest region is smaller, but the overall accuracy in the Central South region is poor. By referring to the relevant data, when using the data of TanDEM to generate DEM, its accuracy has a great relationship with the vegetation coverage rate of the area. High forest coverage rate will seriously affect the coherence of SAR data, and then affect the accuracy of generated DEM.

Key words: Mainland China, TanDEM-X 90 m DEM, ICESat/GLA14, error, influencing factor, regularities of distribution, fidelity