Introduction
Digital Elevation Models (DEMs) are fundamental datasets in civil engineering, environmental science, hydrology, and geospatial studies. Processing DEMs requires specialized software capable of visualization, editing, hydrological analysis, terrain modeling, and export to various formats.
Choosing the right software depends on project requirements — accuracy, ease of use, processing speed, and advanced analysis tools. This article covers:
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Popular software for DEM processing,
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How to download DEM datasets,
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Typical processing workflows,
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Shortcut keys for faster operations, and
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A comparison table for easy selection.
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| Image source: QGIS Tutorials and Tips |
DEM Data Download Sources
Before processing DEMs, you first need the data. Major free sources include:
| Source | Resolution | Notes |
|---|---|---|
| USGS EarthExplorer | 1m, 10m, 30m | SRTM, LiDAR, ASTER GDEM available. |
| OpenTopography | High-resolution LiDAR | Global coverage, especially USA focus. |
| Copernicus DEM (ESA) | 30m, 90m | Free global DEM, excellent for Europe. |
| ALOS World 3D (AW3D30) | 30m | Japan Aerospace Exploration Agency. |
| NASA SRTM | 30m global | Good for flood modeling and terrain. |
| Indian NRSC Bhuvan | Various, 30m, Indian focus | National data for India. |
Popular Software for DEM Processing
Here’s a breakdown of the most used software for DEM analysis:
| Software | License | Main Strengths |
|---|---|---|
| QGIS | Free/Open Source | Hydrology, terrain analysis, plugins. |
| ArcGIS Pro | Paid | High-end terrain modeling, advanced tools. |
| Global Mapper | Paid (affordable) | Fast DEM editing, volume calculations. |
| GRASS GIS | Free/Open Source | Advanced geospatial modeling. |
| ERDAS Imagine | Paid | DEM editing, ortho-rectification. |
| ENVI | Paid | DEM from stereo imagery, remote sensing. |
| SAGA GIS | Free/Open Source | Strong for geomorphological modeling. |
Typical Step-by-Step DEM Processing Workflow
Here’s a generalized DEM processing workflow (example shown for QGIS):
Step 1: Data Download
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Visit USGS EarthExplorer.
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Select area of interest.
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Choose DEM (SRTM, ASTER).
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Download in GeoTIFF format.
Step 2: Import DEM into Software
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Open QGIS →
Layer→Add Raster Layer→ Select downloaded DEM.
Step 3: Visualization
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Apply hillshade effect:
Raster→Analysis→Hillshade. -
Create contour lines:
Raster→Extraction→Contour.
Step 4: Hydrology Analysis
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Fill sinks/depressions:
Processing Toolbox→r.fill.dir. -
Generate flow direction:
Processing Toolbox→r.watershed. -
Watershed delineation:
Use flow accumulation and outlet selection.
Step 5: Export Outputs
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Export processed DEM or analysis results:
Right-click layer→Export→Save As.
Shortcut Keys to Speed Up Work
| Operation | Shortcut Key (QGIS/ArcGIS Pro) |
|---|---|
| Add Raster Layer | Ctrl+Shift+R (QGIS) / Ctrl+Shift+R (ArcGIS) |
| Zoom to Layer | Ctrl+J (QGIS) / Alt+Z (ArcGIS) |
| Open Attribute Table | F6 (QGIS) / Ctrl+T (ArcGIS) |
| Pan | Spacebar + Drag Mouse |
| Identify Features | Ctrl+Shift+I (QGIS) / Ctrl+Shift+I (ArcGIS) |
| Start Processing Toolbox | Ctrl+Alt+T (QGIS) |
Pro Tip: Customize your own shortcuts in settings for maximum efficiency!
Advanced DEM Processing Capabilities by Software
| Feature | QGIS | ArcGIS Pro | Global Mapper | SAGA GIS |
|---|---|---|---|---|
| Hillshade, Contour Generation | ✅ | ✅ | ✅ | ✅ |
| Watershed & Flow Accumulation | ✅ | ✅ | ✅ (easy) | ✅ (advanced) |
| Cut/Fill Volume Calculation | ✅ (plugin) | ✅ | ✅ (very fast) | ❌ |
| DEM Interpolation | ✅ | ✅ | ✅ | ✅ |
| Raster Algebra (Map Calculator) | ✅ | ✅ | ✅ | ✅ |
| Hydrological Sinks Removal | ✅ | ✅ | ✅ | ✅ |
| Machine Learning Classification | Plugins | Built-in (deep learning) | ❌ | ❌ |
| Scripting Support (Python/R) | ✅ | ✅ | ✅ | ✅ |
Example Mini-Project: Watershed Delineation in QGIS
Objective: Identify watershed boundary for a small river.
Steps:
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Load DEM.
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Fill depressions (to ensure continuous flow).
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Generate Flow Direction (using D8 algorithm).
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Create Flow Accumulation Raster.
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Threshold Accumulation to extract streams.
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Define Outlet Point manually.
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Use Watershed tool to delineate catchment area.
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Export shapefile of watershed.
Time Estimate: 15–20 minutes using QGIS!
Best Practices When Processing DEMs
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Always reproject DEMs into a projected CRS (like UTM) for accurate distance/slope calculations.
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Check for artifacts (e.g., sinks, spikes) and apply preprocessing if necessary.
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Use appropriate resolution DEM for the analysis (e.g., 1m for flood modeling, 30m for general watershed).
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Document your steps for reproducibility and reporting.
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Backup raw data before heavy processing.
Conclusion
Processing DEMs unlocks a vast world of spatial and topographic analysis possibilities. Whether you are working on watershed management, flood modeling, or erosion control, selecting the right software platform and following efficient processing workflows ensures the best outcomes.
QGIS offers an excellent free solution for most needs, while ArcGIS Pro excels for large-scale or complex professional workflows. Global Mapper stands out for quick and robust terrain edits, and SAGA GIS is a power tool for advanced geospatial modeling.
With the right skills and tools, DEMs can transform complex terrain into actionable insights — making it easier to plan, design, and manage the world around us.
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