Mapping & Survey
Overlap Calculator
Flight-line and capture spacing from your image footprint and overlap %.
Planning aid only — not certified flight-planning software or airspace clearance. Always verify results against your own aircraft's manual and check current regulations before flying. Full disclaimer.
Don't know your footprint? Work it out first with the GSD Calculator.
Spacing
Flight-line spacing: 40.0 m
Capture spacing (along each line): 22.5 m
What to enter
- Footprint width: the ground distance covered by one photo across the flight line.
- Footprint height: the ground distance covered along the flight line.
- Front overlap: how much each photo shares with the next one on the same line.
- Side overlap: how much neighbouring flight lines share.
Get the footprint from the GSD Calculator for your camera and height. Most drones fly mapping missions with the long side of the image across the flight line, so the width is the larger number. If your mapping app rotates the camera or flies with the image the other way round, swap the two values.
What the results mean
- Flight-line spacing = footprint width × (1 − side overlap). This is the distance between neighbouring passes.
- Capture spacing = footprint height × (1 − front overlap). This is how far the drone travels between photos.
Using the default footprint of 100 × 75 m:
| Front overlap | Capture spacing | Side overlap | Line spacing |
|---|---|---|---|
| 70% | 22.5 m | 60% | 40 m |
| 75% | 18.8 m | 65% | 35 m |
| 80% | 15 m | 70% | 30 m |
| 85% | 11.3 m | 75% | 25 m |
Notice how quickly the spacing shrinks at high overlap. Going from 70% to 85% front overlap doubles the number of photos. Going from 60% to 75% side overlap needs 60% more flight lines, and so more flight time.
Turning spacing into camera settings
Most mapping apps ask for overlap percentages and work out the spacing themselves. The calculator is useful when:
- your app or camera triggers by distance: enter the capture spacing directly;
- you trigger by time: divide the capture spacing by your ground speed. At 15 m spacing and 8 m/s, that is a photo every 1.9 s. The Photo Interval Calculator does this and also checks for motion blur;
- you fly a grid manually or in a simple waypoint app: the line spacing tells you how far apart to place the passes.
Check that the camera can keep up. If the interval is shorter than the time the camera needs to save each photo, slow down or fly higher.
Wind changes the spacing you actually get
The spacing is exact only if the drone flies at a steady speed along a straight line. With a crosswind the drone angles into the wind, and the footprint turns with it, which reduces the side overlap. With a headwind or tailwind a time-triggered camera spaces photos unevenly between upwind and downwind lines. Leave a margin of 5–10 percentage points on windy days, or fly when it is calmer; the Flight Window helps you find a steady period.
For recommended overlap values by type of site, including forests, snow and corridors, and why they differ, read our guide to image overlap for drone mapping.