Both methods map large areas from the air far faster than ground survey. The right choice depends on one question more than any other: what is covering the ground?
How photogrammetry works
A drone flies a grid and takes hundreds of overlapping photos. Software matches points between the photos and builds a 3D surface and an orthomosaic, a single map-accurate image of the whole site. Ground control points surveyed with DGPS tie the result to real coordinates.
How LiDAR works
A LiDAR sensor sends laser pulses and measures how long each one takes to return. Some pulses pass through gaps in trees and crops and hit the ground below, so the software can separate the ground from the vegetation and build a true terrain model.
When to choose which
- Open land, construction sites, mines and stockpiles: photogrammetry is usually enough and gives the best image.
- Sites with trees, orchards, crops or bushes: LiDAR gives far more reliable ground levels.
- Road, rail and canal corridors with mixed cover: LiDAR, often with an orthomosaic from the same flight.
- Progress monitoring and visual records: photogrammetry.
What you receive
- Orthomosaic (GeoTIFF) and KMZ for Google Earth
- Digital surface model (DSM) and digital terrain model (DTM)
- Contour plan in AutoCAD
- Point cloud (LAS / XYZ) for LiDAR jobs
- Cross-sections and L-sections where needed
Accuracy comes from the ground
No drone survey is better than its control. Ground control points and independent check points, surveyed with DGPS, are what make the final drawing trustworthy. Always ask for the check-point comparison in the report.
Permissions and airspace
Drone flights in India follow the DGCA Drone Rules. The Digital Sky airspace map divides the country into green, yellow and red zones. Green zones can usually be flown without prior permission, while yellow and red zones need approval before flying. Check the zone of your site early, because approvals can take time.
Not sure which method fits your site? Send the location or a KML and we will suggest the method, the deliverables and the price.