MEASURED, NOT CLAIMED
Our surface differenced against a terrestrial laser scan of the same pit, cell by cell on a 25 cm grid — 43,698 cells compared.
9 cmmedian difference
from the laser
from the laser
| within 25 cm | 97.5% |
| within 10 cm | 54.9% |
| RMS | 13 cm |
| 95th percentile | 23 cm |
THE SURVEY
| photographs | 158 |
| surface points | 7.0 M |
| area captured | 256 × 180 m |
| relief | 20 m |
| model resolution | 40 cm |
WHERE WE DIFFER
−50 cm+50 cm
Pale is agreement. Grey is ground the laser reached and the drone did not.
Positioned from the aircraft's own satellite navigation alone — no ground control points. That
places the whole model within about 1.4 m absolutely; surveyed control removes even that. The
figures above describe the shape, which is what a volume is made of.
Surface shown is the measured 40 cm model; 1.3% is interpolated across small gaps and
larger gaps are left open rather than invented.
Demonstration imagery: Shahbazi, Ménard, Sohn & Théau (2019),
Unmanned aerial image dataset: Ready for 3D reconstruction, Data in Brief,
doi:10.1016/j.dib.2019.103962 — CC BY. Reconstruction and measurements by Northline.
Scan-derived and intended to support expert review — not survey-grade.