Ground Control Points
Physical markers placed on the ground and precisely surveyed before a drone flight, used to anchor the resulting photos or 3D model to real-world coordinates rather than leaving the result floating in an arbitrary, unanchored coordinate system.
Why it matters
A drone's own onboard GPS isn't precise enough on its own for survey-grade work. Ground control points give the processing software known, highly accurate reference locations to calibrate against, which is what actually makes the resulting map or model trustworthy enough to take real measurements from.
On a real project
A surveyor sets several ground control point markers across a site using a total station to establish their exact coordinates before a drone flight, giving the drone mapping software fixed, known reference points to calibrate the final orthomosaic against.
Who this matters most to
A Surveyor establishes ground control points with survey-grade precision, work a Drone/UAV Specialist then relies on to anchor the drone data accurately.
Where this goes wrong
A drone mapping project skips setting ground control points to save time, relying only on the drone's onboard GPS for positioning. The resulting map looks fine visually but is measurably less accurate than survey-grade work, a problem that only surfaces once someone tries to use it for a precise measurement.