Ground Sample Distance (GSD) Calculator

Choose the right flight height for the detail you need in your maps, models and inspections.

1-inch sensor ≈ 13.2 mm, 1/1.3-inch ≈ 9.6 mm, 1/2-inch ≈ 6.4 mm.
The actual lens focal length, not the 35 mm equivalent.

Ground sample distance

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Footprint width–
Footprint height–
Area per photo–
Typical use–

How the GSD Calculator Works

Ground sample distance tells you how much ground each pixel covers. It depends on four things: how high you fly, how wide the sensor is, the lens focal length and how many pixels the image has across. The formula used by photogrammetry software is:

GSD (cm/px) = (sensor width × altitude × 100) ÷ (focal length × image width)

Multiply GSD by the image width and height to get the photo footprint on the ground.

Worked Example

A 1-inch sensor (13.2 mm wide) with an 8.8 mm lens and 5,472 px images, flown at 100 m, gives a GSD of about 2.74 cm/px. Each photo covers roughly 150 × 100 m. Drop to 60 m and GSD improves to about 1.64 cm/px, but each photo covers less, so you need more photos.

Choosing the Right GSD

  • Under 1.5 cm/px: roof and facade inspections, detailed as-built surveys.
  • 1.5 to 3 cm/px: topographic surveys and construction sites.
  • 3 to 5 cm/px: stockpile volumes and progress mapping.
  • 5 cm/px and above: agriculture and large rural areas.

Accuracy vs Resolution

GSD is resolution, not accuracy. Absolute accuracy also depends on GNSS positioning, ground control points and processing. RTK drones like the Skysdrone agriculture drone help a lot. As a rule of thumb, horizontal accuracy is often one to three times the GSD when the survey is done well.

Once you know your altitude, plan the whole job with the mapping area calculator. If mapping could become paid work, see how to make money with a drone.

FAQ

Frequently Asked Questions

What is ground sample distance (GSD)?

GSD is the real-world distance between the centres of two neighbouring pixels in an aerial image. A GSD of 2 cm/px means each pixel covers 2 cm of ground.

What GSD do I need for mapping?

Around 1 to 2 cm/px suits detailed site surveys and inspections, 2 to 5 cm/px suits construction progress and volume work, and 5 to 10 cm/px is fine for agriculture and large-area mapping.

How do I lower my GSD?

Fly lower, use a longer focal length lens or use a camera with more pixels across the same sensor width. Flying lower means more photos and longer flights.

Keep Planning

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