Ground Sampling Distance (GSD)
Definition
The dimension on the ground represented by one pixel in an image. A 10 m GSD means each pixel covers a 10 m x 10 m area. Forensic detection of a single grave typically requires GSD well below 1 m, achievable by UAV or high-resolution commercial satellites.
- Definition
- Ground area represented by a single image pixel
- Example
- 10 m GSD means one pixel covers a 10 m x 10 m area
- Grave detection need
- Well below 1 m GSD
- Achieved by
- UAV or high-resolution commercial satellites
Common questions
Why does a coarser GSD make single-grave detection unreliable?+
If one pixel already covers several metres of ground, a single grave-sized disturbance blends into surrounding pixels and produces no distinguishable signature. Fine GSD is needed so the grave's vegetation, soil colour, or subsidence anomaly occupies enough pixels to be resolved from background terrain.
Does a finer GSD always mean a better forensic image?+
Not necessarily. Finer GSD increases spatial detail but also increases data volume, atmospheric noise sensitivity, and cost, and it does not by itself improve spectral or temporal resolution. Investigators match GSD to the scale of the target rather than always maximising resolution.
Related terms
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- NDWI
- Normalised Difference Water Index. Computed from green and near-infrared or shortwave-infrared bands. Sensitive to water content in vegetation canopy and surface soil....
- Synthetic Aperture Radar (SAR)
- An active microwave sensor that generates its own energy pulse and measures the return from the surface. Cloud-penetrating and day/night capable. Backscatter...
- Temporal Change Detection
- The comparison of multi-date images of the same area to identify pixels or features that have changed between acquisition dates. A disturbed...
- Thermal Infrared (TIR)
- Sensor bands measuring emitted heat radiation (approximately 8-14 micrometres). Decomposing organic matter generates heat; soil with high moisture retains heat longer than...