Accuracy & standards
Accuracy you can prove, not just promise.
Anyone can quote a number. We control every survey to OS grid, test it against independent checkpoints and publish the result — so you can rely on the data and defend it.
01Our approach
Control. Independence. Evidence.
01
Control
A surveyed network of ground control points tied to OS Net via network RTK or a static GNSS base, observed before we fly.
02
Independence
Checkpoints are surveyed like control but never used in processing, so they give an honest test of the finished model.
03
Evidence
Every report states the achieved RMSE and residual at every checkpoint — not a brochure figure.
02Checkpoint report
Every residual, on the record.
Vertical RMSE (12 checkpoints)
±11.6 mm
Specification ±30 mm
03By method
What accuracy to expect.
| Method | Horizontal | Vertical | Notes |
|---|---|---|---|
| Photogrammetry, RTK + GCPs, 1.0–1.5 cm GSD | ±15–25 mm | ±20–30 mm | Design-grade on open, textured ground |
| Photogrammetry, RTK only (no GCPs) | ±30–50 mm | ±50–100 mm | Mapping, context and progress records |
| LiDAR (Zenmuse L2 class), with control | ±30–50 mm | ±30–50 mm | True ground under vegetation |
| Volumetric (stockpiles) | — | — | Volumes typically within ±1–2% |
04Coordinate systems
On the grid, first time.
Unless you specify otherwise, we deliver in OSGB36 British National Grid with heights above Ordnance Datum Newlyn, transformed from ETRS89 using the OSTN15 and OSGM15 models. Local site grids, Irish Grid and ETRS89 are available on request.
Control is observed with survey-grade GNSS, connected to OS Net through a network RTK service or a static base, and checked against a known mark where one is available.
Every survey report includes
- Project extent, dates, weather and flight parameters
- Aircraft, sensor, calibration and GNSS equipment
- Coordinate reference system, geoid and transformation used
- Ground control and checkpoint coordinates with observation method
- Residuals at every checkpoint (X, Y, Z) and overall RMSE
- Areas of reduced confidence (vegetation, water, occlusion) marked on plan
- Deliverable list with formats, versions and file naming
FAQ
Accuracy questions
Root mean square error summarises how far the survey differs from independently measured checkpoints. An RMSE of 20 mm means the typical difference is about 20 mm; individual points can be larger, which is why we also publish every residual and flag areas of lower confidence.
Yes. We routinely tie into a client’s existing control or site grid, and can deliver in both the site system and OSGB36 so designers and setting-out engineers work from the same data.
Our specification and reporting are aligned with RICS guidance on measured surveys of land, buildings and utilities. We can work to your own specification or a tender specification where that is stricter.
Photogrammetry cannot see through vegetation or reliably measure water surfaces. We mark these areas on the confidence plan, use LiDAR where ground under canopy matters, and infill critical detail with GNSS observations.
Start a project
Tell us the outcome. We’ll specify the survey.
- 01We aim to reply within one hourA drone surveyor, not a salesperson, reviews your brief and calls if anything needs clarifying.
- 02Fixed quote & method statementScope, accuracy specification, deliverables, programme and RAMS — in writing.
- 03Fly, process, deliverCapture on your programme, then CAD-ready data with a verified accuracy report.