Resolution

Adapted from the article on https://appliedsciences.nasa.gov/join-mission/training/english/arset-fundamentals-remote-sensing

Resolution depends upon satellite orbit configuration and sensor design. Different sensors have different resolutions.

Spatial resolution is the geographical area covered by a pixel in a satellite’s image. Generally, the higher the spatial resolution, the less area is covered by a single pixel.

Temporal Resolution

Temporal resolution is the revisit period of a satellite. It is the time it takes for a satellite to image the same area at the same viewing angle a second time.  It depends on the satellite and sensor capabilities, the overlap of the satellite’s path, and latitude of the satellite.

Some satellites have greater temporal resolution because:

  • they are able to maneuver their sensors
  • they have increasing overlap at higher latitudes

Spectral Resolution

Spectral resolution describes the ability of a sensor to detect fine wavelength intervals. Instruments detect different ranges of wavelengths along the electromagnetic spectrum, referred to as bands. The narrower a wavelength range is, the finer the spectral resolution is.  More and finer spectral channels enable remote sensing of different parts of the Earth’s surface.

Examples:

  • Landsat (7-11 bands)
  • MODIS (36 bands)
  • AVIRIS (256 bands)

Radiometric Resolution

Radiometric resolution describes a sensor’s ability to discriminate differences in energy (or radiance). The better the radiometric resolution, the more sensitive the sensor is to small differences in energy. It is determined by multiple factors, chief among these are the saturation radiance – the “brightest” thing detectors can measure – and how the radiance measurements are quantized (turned into a digital bit stream).

  • 12 bit sensor, 4,096 levels: MODIS, MISR
  • 10 bit sensor, 1,024 levels: AVHRR
  • 8 bit sensor, 256 levels: Landsat TM
  • 6 bit sensor, 64 levels: Landsat MSS

Posted on July 13, 2021 Tags: