Ground Sample Distance (GSD)

Ground Sample Distance (GSD) defines the spatial resolution of satellite imagery — the distance between the centres of adjacent pixels on the ground. A satellite with 0.3 m GSD can resolve objects 30 cm across; one with 10 m GSD can only distinguish features 10 metres or larger. GSD depends on the sensor's focal length, pixel size, and orbital altitude. Commercial high-resolution providers include Maxar (WorldView, 30 cm GSD), Airbus (Pléiades Neo, 30 cm), and Planet (SkySat, 50 cm). Sentinel-2 provides 10 m multispectral imagery freely. Lower orbits give better GSD but shorter swath width and higher atmospheric drag.