Land Survey Drone Pilots

What this service involves

An aerial land survey photographs a parcel of ground from above on a planned grid, with each frame overlapping its neighbours, so the images can be assembled into a single measured picture of the site. The aircraft flies at a fixed height along parallel lines, which is what makes the overlap consistent enough to work with afterwards.

The flight is the first half of the job. The second half is processing, where the overlapping frames become an orthomosaic, a scaled plan view with the lens distortion taken out, and usually a terrain model alongside it. How the model is tied to real coordinates is either surveyed markers placed on site and captured in the imagery, or a positioning system on the aircraft that records where each frame was taken, or both. How much of the first a job needs is something practitioners genuinely differ on, and what settles it is the tolerance the output has to meet.

Who hires drone pilots for this, and why

Land agents and developers assessing a site before purchase, who need boundaries, access and topography visible in one image rather than pieced together from several visits.

Planning consultants preparing an application, where a current plan view of the site as it actually is carries more weight than an old drawing.

Civil engineers and groundworks contractors setting out, who need levels across the whole site rather than at the points somebody happened to walk to.

Landowners in a boundary dispute, where a dated, scaled image of the ground is the evidence.

What to expect on the day

Expect the flight itself to be a small part of the day. Ground control markers are placed and surveyed first, the grid is flown, and the aircraft lands well before the work is finished. Larger sites are flown in several batteries, and a site with tall trees or structures needs the lines planned around them.

Deliverables are normally an orthomosaic, a digital terrain or surface model, and the raw imagery. What each is good for depends on the ground control: the difference between a plan that looks right and a plan you can measure off is entirely in that step, so it is worth asking what control was used before commissioning the work.

Land Survey: frequently asked questions

How accurate is a drone land survey?

Accuracy is a specification rather than a property of the method, and practitioners differ on how it is best achieved. Surveyed markers on the ground are the traditional answer, and aircraft carrying survey grade positioning have made that an open question rather than a settled one, with peer reviewed work published specifically to ask whether markers are still required. What is not disputed is that the result has to be demonstrated on points that were not used to build the model, so the useful thing to ask is what tolerance was worked to and how it was checked.

Can it survey ground under trees?

Not photographically. Aerial photography records what the camera can see, so anything under a canopy is not in the data. Laser scanning is a different instrument that behaves differently over vegetation, and it is a separate instruction with its own page rather than a setting on this one. Failing that, sites with significant tree cover usually need the wooded areas surveyed from the ground and the open areas flown.

What stops the flight going ahead on the day?

Wind and rain, principally, and low sun. Long shadows across a site degrade an orthomosaic in a way that is hard to correct afterwards, so a survey flight is often planned for the middle of the day rather than the start of it.

Drone pilots offering Land Survey