资源三号卫星DEM数据与全球开放DEM数据的误差对比

全球开放DEM数据为数字地形分析提供了重要数据源。与已有的全球开放DEM数据相比,资源三号卫星具有更高的空间分辨率、更大的覆盖范围和更好的现势性。将资源三号卫星生成的DEM数据与全球开放DEM数据进行误差对比则为基于资源三号卫星的全球DEM数据研制提供科学依据。本文以山西省中部太原市为研究区,基于高精度激光点云数据生成DEM为参考数据,对资源三号卫星影像生成的DEM数据与全球典型的开放DEM数据(AW3D30、SRTM1和ASTER GDEM)的误差进行了对比分析,并获得了其在不同坡度等级下绝对误差与相对误差的平均值、平均绝对值、均方根值和标准偏差值。研究结果表明:①4种DEM数据的误差分布均具有较好的对称性。同时,平均误差接近于0 m,SRTM1和ASTER GDEM数据更是如此。因此均方根误差值与标准偏差值近似一致;②资源三号DEM具有最高的精度,误差最小(均方根误差4.6 m)。其次为AW3D30数据(均方根误差5.6 m)和SRTM1数据(均方根误差8.8 m)。ASTER GDEM数据误差最大(均方根误差12.6 m),精度最差;③资源三号DEM、SRTM1和ASTER GDEM数据的误差均随坡度的变大而增大,而AW3D30数据误差随着坡度增加呈现先减小后增大的趋势。总体上,与其他3种DEM数据相比,资源三号DEM在所有坡度范围均具有最小的误差值。

Error Comparison among the DEM Datasets Made from ZY-3 Satellite and the Global Open Datasets

Global open DEM datasets provide important data sources for digital topographic analysis. Compared to the existing global open DEM datasets, the DEM data made from ZY-3 Satellite have higher spatial resolution, wider coverage and better currency, which results to a great likelihood to produce a global DEM dataset with high quality from ZY-3 Satellite. So the error comparison among the DEM datasets made from ZY-3 Satellite and the global open datasets will provide scientific basis for the global DEM dataset production made form ZY-3 Satellite data. Taking the Taiyuan City (the middle region of Shanxi Province) as a test area, this paper made an error comparison among the DEM datasets made from ZY-3 Satellite (ZY-3 Satellite DEM) and three typical global open DEM datasets (AW3D30, SRTM1 and ASTER GDEM) based on the referencing DEM data produced by laser-point cloud data with high accuracy. Meanwhile, the mean value, mean absolute value, root mean square value and standard deviation value are computed for the absolute error and the relative error at different slope classes. The research results show: (1) the error distributions for all of the four DEM datasets show relatively good symmetry. Meanwhile, the mean error value is approximate to 0 m, especially for the SRTM1 and ASTER GDEM data. So the root mean square error values and the standard deviation error values are approximate for all the four DEM datasets. (2) ZY-3 Satellite DEM has the lowest root mean square error value (4.6 m), so it has the highest accuracy. The next is the AW3D30 data (with root mean square error value of 5.6 m), then the SRTM1 data (with root mean square error value of 8.8 m). ASTER GDEM has the highest error values (with root mean square error value of 12.6 m), so it has the lowest accuracy. Meanwhile, the relative error and the absolute error show similar rules for the four DEM datasets. (3) The errors of the ZY-3 Satellite DEM, SRTM1 and ASTER GDEM data rise with slope increasing. The error of AW3D30 data shows an undulation tendency of rising first, and then falling with slope increasing. The error for the AW3D30 data is lower than that for the SRTM1 data at any slope classes except for the 0°~2° class. At all the slope classes, ASTER GDEM data has the highest error values of all. Overall, compared to other three DEM datasets, ZY-3 Satellite DEM data has the lowest error values and the highest accuracy at all the slope classes.