Case study by SPH Engineering · UgCS · Photogrammetry
UgCS Circlegrammetry cuts drone mapping time by 64%
Researchers at Dalhousie University in Canada compared UgCS Circlegrammetry with standard oblique missions over a tightly planted orchard. Circlegrammetry flew far faster and needed far fewer images, with the same mapping accuracy. The study was published in the ISPRS Open Journal of Photogrammetry and Remote Sensing in November 2025.
The challenge
The team needed accurate 3D maps of a 2.45-hectare orchard of about 450 dense, conical fir trees, packed into tight rows on uneven ground with a 7% slope. Standard oblique missions must fly well beyond the survey boundary to capture enough imagery, which is impractical when roads, neighbouring land or obstacles limit where the drone can go.
How Circlegrammetry works
Circlegrammetry is a UgCS mission type from SPH Engineering. Instead of a grid, the drone flies a series of overlapping circles with the camera angled inwards towards each circle's centre. Every object is seen from many directions, which gives strong 3D reconstruction, and the drone does not need to fly far outside the area.
The test
The researchers flew five missions over the same orchard with identical hardware: three Circlegrammetry missions at different settings, plus a standard oblique mission and DJI Smart Oblique Capture. Eight ground control points were surveyed with RTK-GNSS to check accuracy.
The results
- Circlegrammetry with 25% overlap finished in 4 min 10 s, against 11 min 41 s for the standard oblique mission: 64% faster.
- It needed 158 images instead of 731, and processing took 54 minutes instead of 5 hours 21 minutes.
- Ground control point RMSE stayed between 1.38 and 1.53 cm across all methods, with no significant difference in measured tree heights.
- Standard oblique missions flew 58 m beyond the survey area on each side; Circlegrammetry at 50% overlap needed only 28 m.
The researchers found 50% circle overlap gave the best balance of speed and detail. One trade-off: Circlegrammetry captured fewer points in the lower canopy, so they suggest adding low-angle passes around the edge where lower detail matters.
Where this applies in India
Circlegrammetry suits mapping jobs where speed matters and the drone cannot fly far outside the site:
- orchards, plantations and crop research plots;
- 3D mapping of buildings, structures and construction sites in dense urban areas;
- sites bounded by roads, property lines or restricted airspace;
- survey teams who want more sites per day and faster processing.
SPH Engineering's UgCS training courses are also available through HobiTech.
The equipment, available from HobiTech
| Flight planning | UgCS - Drone Flight Planning Software: see UgCS PRO, UgCS EXPERT and UgCS ENTERPRISE |
| Drone and camera | DJI Matrice 300 RTK with Zenmuse P1 was used in the study. Ask us for current compatible drones. |
| Processing | Agisoft Metashape (used in the study) |
Case study by SPH Engineering, published January 2026, based on Bilodeau et al. (2025), ISPRS Open Journal of Photogrammetry and Remote Sensing, 18, 100111. This page summarises it in our own words; the research was carried out by Dalhousie University, not by HobiTech. Read the original case study on SPH Engineering ↗
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