LiDAR (Light Detection and Ranging) and photogrammetry are two powerful remote sensing technologies used extensively in Geographic Information Systems (GIS) for mapping, modeling, and analyzing Earth’s surface and features. Here’s a breakdown of each and how they are applied in GIS:
LiDAR in GIS
What is LiDAR?
LiDAR uses laser pulses emitted from an aircraft or drone to measure distances to the Earth’s surface. These pulses return elevation data, allowing the creation of highly accurate 3D models.
Key Outputs:
- Point clouds
- Digital Elevation Models (DEM)
- Digital Surface Models (DSM)
- Canopy Height Models (CHM)
- Contour lines and terrain models
Applications in GIS:
- Topographic mapping (bare-earth modeling)
- Flood modeling and hydrology
- Forestry analysis (e.g., biomass estimation, canopy density)
- Urban planning and infrastructure development
- Power line corridor mapping
- Coastal erosion and shoreline monitoring
Photogrammetry in GIS
What is Photogrammetry?
Photogrammetry involves using overlapping aerial or drone photographs to create 2D and 3D spatial data through triangulation. It can be done with passive sensors (like cameras), unlike LiDAR’s active laser system.
Key Outputs:
- Orthophotos (geometrically corrected aerial images)
- 3D point clouds
- Digital Surface Models (DSM)
- Textured 3D meshes
- Contour maps
Applications in GIS:
- Land-use/land-cover mapping
- Cadastral mapping
- Archaeological documentation
- Construction monitoring
- Environmental impact studies
- Change detection over time
Comparison of LiDAR and Photogrammetry
| Feature | LiDAR | Photogrammetry |
|---|---|---|
| Sensor Type | Active (laser) | Passive (camera) |
| Lighting Dependency | No (can work at night) | Yes (needs sunlight) |
| Vegetation Penetration | High (can reach ground under trees) | Limited |
| Resolution | Very high (cm-level accuracy) | High, but depends on image quality |
| Cost | More expensive | More affordable (especially via drones) |
| Best Use | Detailed terrain and elevation models | Image-rich 3D models and visual mapping |
🔧Integration in GIS
Both LiDAR and photogrammetry can be:
- Processed in software like ArcGIS, QGIS, Global Mapper, or CloudCompare.
- Combined to create hybrid datasets: e.g., LiDAR for accurate elevation + photogrammetry for texture/color.
- Used for automated feature extraction (e.g., building footprints, vegetation classification).
Summary
| LiDAR is best for: | Photogrammetry is best for: |
|---|---|
| Precise terrain modeling | Visual surface representation |
| Forest and utility mapping | Urban and cultural heritage mapping |
| Elevation-based analysis | Orthophoto creation and 3D modeling |
If you’re working on a GIS project and need help choosing between LiDAR or photogrammetry—or using both—We can help tailor a workflow. Just let me know your use case.
