Ground Sampling Distance (GSD) is a term used in remote sensing and photogrammetry that refers to the size of the smallest discernible ground element or feature in an image acquired by a sensor.
In simple terms, GSD represents the resolution of an image and is the distance between two consecutive pixel centers on the ground. GSD is typically measured in meters or feet per pixel and is determined by the altitude of the sensor, the focal length of the lens, and the size of the image sensor.
A smaller GSD means that an image has higher spatial resolution and can capture more detail, while a larger GSD means that an image has lower spatial resolution and captures less detail. GSD is an important consideration in many applications, such as mapping, land-use analysis, and environmental monitoring, as it affects the accuracy of measurements and the level of detail that can be extracted from the image.