全球数字高程产品概述

Review on global digital elevation products

随着世界各国乃至全球信息化和数字化的发展以及全球化热点问题的研究,高精度、高分辨率全球数字高程产品在广泛的应用领域中扮演着越来越重要的角色。为了方便不同用户根据个人需求选择合适的数据产品,本文首先论述了数字高程产品的精度衡量指标,并对其常用的指标进行等价描述,以便不同数字产品之间的比较分析;然后从全球化高程数据的获取方式出发,经由最初的多源数据融合,到后续基于光学立体摄影测量及合成孔径雷达干涉测量InSAR (Interferometric Synthetic Aperture Radar)的全球测图,对其发展的ETOPO、GTOPO30、GMTED2010、ASTER GDEM、AW3D30、SRTM及TanDEM-X DEM全球化数据产品的主要性质和特点进行详细介绍,并简单概括了不同数字产品的发展历程。在此基础上,本文以宁夏回族自治区吴忠市一座山脉为例,通过定性及定量对比的方式详细分析了1″及3″经纬度格网分辨率下的数字高程产品。分析表明,对于采用同一种技术手段生产的数字高程产品,AW3D30及ASTER GDEM均展现出相对丰富的地貌细节特征,均优于SRTM及TanDEM-X DEM产品,但ASTER GDEM产品颗粒效应明显,且产品精度较低;而TanDEM-X DEM是从更高分辨率产品重采样获取,因此相对平滑;就数字高程产品的高程精度而言,TanDEM-X DEM产品精度最高,其次为AW3D30及SRTM产品,均远优于由多源数据融合获取的全球数字产品。

Digital elevation products are the digital expression of terrain and elevation information, which has been widely utilized in the fields of climate, meteorology, topography, geological disasters, soil, and hydrology. Meanwhile, the development of information and digitalization all over the world and the research of major global issues have emphasized the increasingly becoming important role of highprecision and-resolution global digital elevation products. Therefore, the public free digital elevation products are comprehensively described and analyzed in this study to facilitate different users to select appropriate data products depending on their personal requirements.This study first discusses the different measurement indexes of digital elevation products’ accuracy. Moreover, the equivalence relationship between the common measurement indexes is derived to compare and analyze different digital elevation products. The global elevation data acquisition modes are explored first. The main properties and characteristics of ETOPO, GTOPO30, GMTED2010, ASTER GDEM, AW3 D30, SRTM, and TanDEM-X DEM global data products are introduced in detail through the initial data fusion and the subsequent global mapping based on optical stereo photogrammetry and interferometric synthetic aperture radar techniques. The development history of different products is also briefly described. The parameters and elevation accuracy among the aforementioned digital elevation products are then summarized and comparatively analyzed. The results are shown in Table 7 and 8, respectively.On this basis, the different data products under 1″ and 3″ resolution for a mountain located in Wuzhong City, Ningxia Hui Autonomous Region are analyzed in detail by means of qualitative and quantitative comparison. The visual analysis shows that the AW3 D30 and ASTER DEM products exhibit the relatively rich landform detail features, and they are both superior to the SRTM and TanDEM-X DEM elevation products. However, the particle effects obviously appear in the ASTER GDEM products, and the precision of these products is low. Among these products, the TanDEM-X DEM products are relatively smooth because they are derived by resampling the high-resolution products. In terms of elevation accuracy, TanDEM-X DEM products have the highest accuracy and are followed by AW3 D30 and SRTM products. These products are greatly superior to the global digital elevation products obtained by multi-source data fusion. The quantitative difference analysis results of different products are consistent with the conclusion mentioned above.In general, adopting the advanced satellite remote sensing technology to obtain elevation data with uniform data source, quality, and precision will be the development trend of global digital elevation products. Furthermore, the application field of digital elevation products with high precision and resolution obtained by advanced techniques will be expanded from the initial change research of global large area to the application research related to elevation of urban and even local small area. Therefore, domestic digital elevation products, which can be controlled independently, are urgently demanded. Meanwhile, the popular domestic LuTan-1 SAR satellite with the interference as main task will soon be launched, and it will provide a good technical foundation for the production and acquisition of domestic global digital elevation products.