DEM

A Digital Elevation Model (DEM) is a digital representation of the bare-earth ground surface, stored as a raster grid where each cell value represents the elevation at that location. DEMs are fundamental to terrain analysis and 3D visualization in GIS.

• DEM (Digital Elevation Model): General term for elevation grids; sometimes specifically refers to bare-earth elevation
• DTM (Digital Terrain Model): Bare-earth surface excluding vegetation and structures
• DSM (Digital Surface Model): Top surface including vegetation, buildings, and other features

• USGS 3DEP: National Elevation Dataset at 1/3 arc-second (approximately 10 meter) resolution
• SRTM: Shuttle Radar Topography Mission, global 30-meter coverage
• LiDAR: High-resolution point cloud data processed into DEMs (sub-meter resolution)
• Photogrammetry: Derived from stereo aerial or satellite imagery
• Drone surveys: Site-specific high-resolution elevation data

Applications in mining: - Topographic analysis for mine site selection and design - Slope and aspect calculations for engineering - Viewshed analysis for visual impact assessment - Drainage analysis and watershed delineation - Volume calculations for stockpiles and excavations - 3D visualization and flythrough animation - Cross-section and profile generation - Access road design and route planning

Common DEM operations: - Slope calculation (steepness of terrain) - Aspect calculation (direction of slope) - Hillshade generation (shaded relief visualization) - Contour generation - Hydrological modeling (flow direction, accumulation) - Cut-and-fill analysis

DEMs are essential for nearly all site-specific analysis in mining and land management.