Sensor

GSD — Ground Sample Distance

The size of one pixel on the ground. 30 cm GSD means each pixel covers a 30 cm square.

GSD: 1 m
Scene size: 30 m × 30 m
Pixels in scene: 900
Typical sensors: Gaofen-2 pansharpened
What you can resolve: Building footprints, roads, large features

Fig. 1 GSD (Ground Sample Distance) sets the size of one pixel on the ground. Drag the selector to compare what different resolutions resolve. The same 30 m × 30 m scene is rendered at each resolution — the finer the GSD, the more ground detail survives the sampling.

GSD is the real-world size of one pixel. Lower number = sharper image. WorldView-3 at 30 cm GSD means each pixel covers a 30 cm × 30 cm square of ground. Sentinel-2 at 10 m GSD means each pixel covers a 10 m × 10 m square.

GSD alone is misleading

A 30 cm image that has been poorly pansharpened or captured at high off-nadir can look worse than a well-processed 50 cm image. When you say 'I need 30 cm' you usually mean you want to see something specific — a car, a roof feature, a pipeline joint — and 30 cm is the number you've heard. Often the actual goal can be solved with 50 cm and good processing at a fraction of the price.