How the calculator works
GSD is the size of one image pixel on the ground. It is set by the camera sensor, the lens and the flying height:
GSD (cm/px) = sensor width (mm) × height (m) × 100 ÷ ( focal length (mm) × image width (px) )
The footprint is the ground area covered by one photo. The flight height for a target GSD reverses the same formula. Camera presets use manufacturers' published sensor sizes; check your own camera's specification before planning a project.
Using GSD to plan a survey
- Accuracy: with good ground control, horizontal accuracy is typically one to two times the GSD and vertical accuracy one and a half to three times. Read how accurate a drone survey is.
- Height limit: in India's green zones, flights up to 400 ft (about 120 m) above ground need no permission. Above that, or in yellow and red zones, permission is needed.
- Overlap: mapping flights usually use about 75 to 80% forward and 65 to 70% side overlap. Lower GSD means more photos and longer processing.
Want us to plan it? Send the site and the accuracy you need and we will set the GSD, control and flight plan. See what decides the cost.