Drone surveying in geodesy: when photogrammetry beats a classic survey
Orthophotos, 3D terrain models, point clouds and volumes — how drone surveying with the DJI Matrice 4E works and when it pays off versus a classic survey.
Only a decade ago, aerial capture meant an aircraft, a big budget and a long wait. Today a professional mapping drone captures in one day an area that would take several days with a classic survey — and records every detail of the terrain, not just the points the surveyor chose.
Our office uses the DJI Matrice 4E, a drone built for mapping and surveying. Here is how it works in practice.
How a survey-grade capture is made
- Flight plan — in software we define the area, flight height and image overlap (typically 70–80%). Height determines resolution: the lower we fly, the smaller the ground sampling distance (GSD).
- Ground control — on site we measure ground control points (GCPs) with GNSS RTK equipment, tying the model to the Croatian national coordinate system HTRS96/TM.
- Flight — the drone autonomously flies the grid and captures hundreds or thousands of overlapping photos. The Matrice 4E has an RTK module (horizontal positioning accuracy of 1 cm + 1 ppm per the manufacturer’s specification) and a 4/3” wide camera with a mechanical shutter — important for sharp, distortion-free images in motion.
- Processing — photogrammetry software turns the images into a point cloud, digital surface and terrain models, and an orthophoto.
- Accuracy check — we verify the result on independent check points before delivery.
What you get
- Orthophoto — a geometrically corrected, scaled image on which distances and areas can be measured.
- Digital surface and terrain models (DSM/DTM) — the basis for contours, profiles and design.
- Point cloud — millions of coordinated points for analysis and 3D modelling.
- 3D model — textured representation of buildings, quarries, construction sites.
- Volume calculations — excavations, embankments, material stockpiles.
- Vector base maps (DWG/DXF) for designers.
When a drone is the better choice
| Situation | Drone | Classic survey |
|---|---|---|
| Large open area (several hectares) | ✔ faster and more complete | slower |
| Inaccessible or hazardous terrain | ✔ no need to enter the zone | risky |
| Construction progress monitoring | ✔ repeatable, with a visual record | limited |
| Stockpile and excavation volumes | ✔ the whole surface | sampled points |
| Boundaries under dense vegetation | limited | ✔ |
| Survey report for a small plot in a village | rarely needed | ✔ |
A drone does not replace the surveyor — it is a tool. For many tasks the best result comes from a combination: the drone for a complete picture of the terrain, GNSS and a total station for key points and details.
How accurate is it?
Accuracy depends on flight height, camera, ground control, site conditions and processing. That is why we always state it for the specific project, verified on check points — not as a marketing number.
And legality?
Every commercial flight must be carried out by a registered operator with a trained remote pilot, respecting UAS geographical zones and regulations. We explain why this matters to the client as well in Why your drone surveyor must be licensed.
Wondering whether your site can be captured by drone? See our drone surveying page or get in touch.