VERTICAL ACCURACY ASSESSMENT OF THE PROCESSED SRTM DATA FOR THE BRAZILIAN TERRITORY

Abstract: This research aims to determine the vertical accuracy of the Interferometric Digital Elevation Model (DEM) obtained from the processed Shuttle Radar Topographic Mission (SRTM) data. The research compared the SRTM-GL1 (Shuttle Radar Topographic Mission-Global 1) with 30-meter resolution and the following 90-meter resolution models: (a) EMBRAPA; (b) Hydrological data and maps based on Shuttle Elevation Derivatives at multiple Scales (HydroSHEDS) (HydroSHEDS), provided by the United States Geological Survey (USGS); (c) Consultative Group for International Agricultural Research-Consortium for Spatial Information (CGIAR-CSI); and (d) Jonathan de Ferranti. The accuracy analysis considered the diverse Brazilian regions, adopting 1,087 field points from the Global Navigation Satellite System (GNSS) trackers or topography methods. The Jonathan de Ferranti model achieved the best accuracy with RMSE of 9.61m among the 90-meter resolution models. Most SRTM models at 1:100,000 scale reached Grade A of the Cartographic Accuracy Standard. However, the accuracy at the 1: 50,000 scale did not achieve the same performance. SRTM errors are linearly related to slope and the most significant errors always occur in forest areas. The 30-meter resolution SRTM showed an accuracy of around 10% better (RMSE of 8.52m) than the model of Jonathan de Ferranti with 90-meter resolution (RMSE of 9.61m).摘要：本研究旨在评估经处理的航天飞机雷达地形测绘任务（Shuttle Radar Topographic Mission，SRTM）数据所生成的干涉型数字高程模型（Interferometric Digital Elevation Model，DEM）的垂直精度。研究对比了分辨率为30米的SRTM-GL1，以及以下四款90米分辨率模型：(a) 巴西农牧业研究公司（EMBRAPA）模型；(b) 由美国地质调查局（United States Geological Survey，USGS）提供的多尺度航天飞机高程衍生水文数据与地图（HydroSHEDS）；(c) 国际农业研究磋商组织-空间信息联盟（CGIAR-CSI）模型；(d) Jonathan de Ferranti模型。精度分析覆盖巴西境内多样的地理区域，采用了来自全球导航卫星系统（Global Navigation Satellite System，GNSS）接收机或地形测量手段的1087个野外实测测点。在90米分辨率的模型中，Jonathan de Ferranti模型精度最优，其均方根误差（Root Mean Square Error，RMSE）为9.61米。多数1:100000比例尺的SRTM模型达到了制图精度标准的A级，但1:50000比例尺下的精度未达到同等水准。SRTM模型的误差与坡度呈线性相关，且最显著的误差始终出现在林区。30米分辨率的SRTM模型精度较90米分辨率的Jonathan de Ferranti模型提升约10%，前者均方根误差为8.52米，后者为9.61米。