DEM获取（免费数据源）
创建 DEM 的高程数据的方法 Lidar Radar Stereo photogrammetry from aerial surveys Structure from motion / Multi-view stereo applied to aerial photography Block adjustment from optical satellite imagery Interferometry from radar data Real Time Kinematic GPS Topographic maps Theodolite or total station Doppler radar Focus variation Inertial surveys Surveying and mapping drones Range imaging 准确度影响因素 terrain roughness; sampling density (elevation data collection method); grid resolution or pixel size; interpolation algorithm; ver...