Ground Sample Distance (GSD) refers to the distance between the centers of two consecutive pixels on the ground as captured by a remote sensing sensor or camera. It measures the spatial resolution of imaging systems, especially in aerial and satellite imagery. GSD is usually expressed in meters (or centimeters) per pixel.
Definition
GSD is the distance between the center points of two adjacent pixels measured on the ground.
Formula for GSD
GSD= (H×P) / F
Where:
H: Flying height or distance from the ground to the sensor (in meters).
P: Pixel size of the sensor (in micrometers or millimeters).
F: Focal length of the camera lens (in millimeters).
Key Points
Smaller GSD: Indicates higher resolution, as each pixel covers a smaller ground area.
Small pixels
More detail visible
Ideal for detailed mapping, surveying, or when precise measurements are required
Sample smaller GSD image:
Larger GSD: Indicates lower resolution, as each pixel covers a larger ground area.
Large pixels
Less detail visible
Suitable for large areas or when you don't need fine details
Implications
High-resolution imagery (low GSD) is essential for detailed analysis, such as identifying small objects.
Low-resolution imagery (high GSD) is used for broader overviews, such as mapping large landscapes.
Example
Imagine a grid of squares on the ground. Each square represents the area covered by one pixel in your image. The side length of one of these squares is the GSD.
A GSD of 10 cm/pixel means each pixel in the image represents a 10 cm × 10 cm area on the ground.
For more information or any questions regarding GSD, please don't hesitate to contact us at:
Email: info@geowgs84.com
USA (HQ): (720) 702–4849
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