Category: Foundations
Pixel
A pixel is the smallest unit in a raster; it represents the sensor’s measurement over a ground area.
Also known as: cell, raster cell
Expanded definition
A pixel is a cell in a raster grid. In satellite imagery, a pixel value represents an average or effective measurement over the area covered by that pixel on the ground.
Pixels are not perfect squares on the surface in all products. Sensor geometry, resampling, and projection can change the effective footprint.
Many real-world surfaces are smaller than a pixel, so pixels can be mixed. For example, one pixel may contain both crop and soil, which affects indices and classification results. Understanding pixel size and mixing is critical when comparing datasets at different resolutions.
Related terms
Raster
A raster is a grid of pixels where each pixel stores a value, commonly used for satellite imagery and elevation models.
Spatial Resolution
Spatial resolution describes the ground detail an image can represent, commonly expressed as meters per pixel.
Resampling
Resampling changes the pixel grid of a raster, for example when reprojecting or changing resolution.