What makes a survey valid?
Minimum criteria for a drone survey to be processed in Clementina and added to the public map.
- 1.
Flight pattern and appropriate altitude
Fly a double grid (grid + cross-grid) at 60–120m above ground level depending on the detail required. Flights above 200m generally fail to produce usable orthomosaics or accurate DEMs.
- 2.
Image overlap
Maintain at least 75% frontal overlap and 65% side overlap. With less overlap, photogrammetry cannot reliably reconstruct the surface.
- 3.
Preserved GPS metadata
Every photo must carry EXIF coordinates. If less than 80% of the images have GPS, the survey is rejected at validation. RTK is optional but recommended for sub-metric accuracy.
- 4.
Light and weather conditions
Avoid harsh shadows and extreme contrast: golden hour or evenly overcast skies give the best results. No wind above 25 km/h. Rain or fog rule out the flight.
- 5.
Full coverage of the area of interest
The covered polygon must contain the entire relevant site, with a 10–20m safety margin outward. Fragmented partial flights are hard to stitch together later.
- 6.
Image quality
RAW or JPG from a drone camera, in focus, no overexposure. Minimum resolution 12 MP per photo. Avoid motion blur (shutter speed ≥ 1/500s recommended).
Version 1.0 · 2026