Photo overlap, the survey grade default.

Overlap is the photogrammetry parameter that quietly decides whether your map reconstructs cleanly or comes back with holes. Too little and the software can’t find tie points; too much and you’ve doubled your flight time for no benefit. The sweet spot is narrower than most pilots realise.

§ 01Try it

Drag the front and side overlap sliders below. Watch the photo footprints either crowd together (over-collection) or pull apart (gaps). The badge in the corner shows the quality assessment.

§ 02Why overlap matters at all

Photogrammetry reconstructs 3D position by triangulating the same ground feature across multiple overlapping photographs. With 75% front and 70% side overlap, every interior point on your ground is photographed by at least 6–8 cameras from different angles — which is what gives the bundle adjustment enough constraints to converge accurately.

§ 03The recommended defaults

For most drone mapping work, the industry-standard starting points are:

§ 04When overlap is too low

Below 65% front or 60% side, the demo above flips to RISKY. Here is what actually breaks:

§ 05When overlap is too high

Going from 75/70 to 85/80 doubles photo count and flight time, but only marginally improves reconstruction quality on normal terrain. The exception is anything with little natural texture (snow, sand, water) where the extra redundancy buys you a workable model.

§ 06Tie points — the math underneath

Each overlapping pair of photographs produces hundreds to thousands of tie points: features (corners, textures, edges) that appear in both images. The photogrammetry engine — usually OpenSfM, Pix4D’s engine, or COLMAP — uses these to triangulate the camera poses and the 3D positions of every visible feature.

Below ~65% overlap, the number of tie points per image pair drops sharply, and so does the geometric strength of the reconstruction. That cliff is what the badge on the demo is warning you about.

§ NEXTRelated field-guide pages