Ground Sampling Distance (GSD)

The Ground Sampling Distance (GSD) is the distance between two consecutive pixel centers measured on the ground. The bigger the value of the image GSD, the lower the spatial resolution of the image and the less visible details. The GSD is related to the flight height: the higher the altitude of the flight, the bigger the GSD value.

 
Example: 
  • A GSD of 5 cm means that one pixel in the image represents linearly 5 cm on the ground (5*5 = 25 square centimeters).
  • A GSD of 10 m means that one pixel in the image represents linearly 10 m on the ground (10*10 = 100 square meters).
 
Note: Even when flying at a constant height, the images of a project may not have the same GSD. This is due to terrain elevation differences and changes in the angle of the camera while shooting. Since the orthomosaic is created using the 3D point cloud and the camera positions, an average GSD will be computed and used. 
 
Information: 
  • How to select camera focal length and flight altitude considering the desired Ground Sampling Distance and terrain to map: 202558849.
  • TOOLS - GSD Calculator: 202560249.
  • Can Pix4Dmapper process images taken at different flight heights?: 202558979.
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