Question 1

How is ground sample distance (GSD) calculated?

Accepted Answer

GSD (the ground size of one pixel) = (sensor width in mm × altitude in m × 100) ÷ (focal length in mm × image width in px), giving centimetres per pixel. So flying higher increases the GSD (coarser detail) and a longer focal length decreases it (finer detail).

Question 2

Is the GSD the same as the final map accuracy?

Accepted Answer

No. GSD only describes the pixel size on the ground; the delivered map or model accuracy also depends on ground control points (GCPs), RTK/PPK quality, overlap, lens calibration and capture conditions, and the achievable horizontal accuracy is often two to three times the GSD. For certified, documented accuracy, talk to our survey team.

Question 3

What overlap should I choose?

Accepted Answer

Common values are 75% front and 65% side as a practical minimum, and 80%/70% for difficult terrain, vegetation or uniform surfaces. The tool starts at 80%/65% and you can change it; higher overlap improves matching but increases the photo count, flight time and processing load.

Question 4

Where do the camera presets come from?

Accepted Answer

The sensor and lens numbers in the presets are taken from the manufacturers’ public datasheets. Your exact unit or lens revision may differ slightly, so verify your camera’s figures and use the “Custom” option to enter them by hand when needed.

Question 5

Is the altitude the tool computes legal to fly?

Accepted Answer

The tool only does the survey math and is not legal advice. Maximum flight heights and drone-operation permits vary by country and region, and there may be no-fly zones or permit requirements. Check your national civil-aviation rules and obtain the required permissions before you fly.

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Drone GSD & photo-plan calculator

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Drone GSD & photo-plan calculator