The GSD is the real-world size of a pixel in your images, and for most drone flights it’s between 1 and 10 cm. A low GSD (1cm) is very high resolution imagery, and a high GSD means lower resolution.

The GSD is determined by:

  • The resolution of your camera sensor — e.g. a 12MP camera will have a higher GSD than a 22MP camera
  • The altitude of your flight — flying higher means a higher GSD
  • The focal length/field of view of your camera — a wider angle camera like a GoPro means a higher GSD

In general, the final accuracy for a model in X and Y is 1–2x the GSD, and 1–3x in the vertical however you will find that the average error tends to be closer to 1x GSD for all axes.

Image source: Doug Corrin, Maps and Photogrammetry

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