The study of the Earth's topographic surface using digital topography is an important component of many problems in the Earth Sciences. The 30-m Shuttle Radar Topography Mission (SRTM) and the Advanced Land Observing Satellite (ALOS) global digital topography datasets have been the most recently available global digital topography datasets. Most users directly download the data/DEMs in their native form assuming a vertical error close to their mission goals. We demonstrate, through the use of 221 dual-frequency static Global Positioning System (GPS) independent ground control points, that the datasets typically have outliers and voids that increase the error by an order of magnitude. Filtering the voids, outliers, and correcting systematic errors significantly improved the vertical accuracy of the datasets. We concluded from our study that the ALOS data generated the most accurate DEM in the Indian subcontinent. This finding needs to be tested and confirmed worldwide for generating the best DEMs.

使用数字地形学研究地球地形表面是地球科学中许多问题的重要组成部分。30米的航天飞机雷达地形任务（SRTM）和高级陆地观测卫星（ALOS）全球数字地形数据集已成为最新可用的全球数字地形数据集。假定垂直错误接近他们的任务目标，大多数用户会以其原始格式直接下载数据/ DEM。通过使用221个双频静态全球定位系统（GPS）独立地面控制点，我们证明了数据集通常具有异常值和空白，从而使误差增加了一个数量级。过滤空隙，离群值和纠正系统误差可以显着提高数据集的垂直精度。从我们的研究中我们得出结论，ALOS数据在印度次大陆上生成了最准确的DEM。此发现需要在全球范围内进行测试和确认，以生成最佳的DEM。