How are Digital Elevation Models (DEMs) generated and what are their applications?

DEM generation methods: photogrammetric processing of stereo imagery, LiDAR point cloud processing, InSAR interferometry, digitizing contours from maps, and ground survey interpolation. Resolution varies from 30m (SRTM) to sub-meter (LiDAR). Applications in civil engineering: cut/fill volume calculation, drainage analysis and watershed delineation, flood modeling, visibility analysis, slope stability assessment, road/canal alignment optimization, and 3D visualization. DEM derivatives include slope, aspect, hillshade, and contours. Quality depends on source data and terrain complexity.