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Resolution of remotely sensed data

Spatial resolution

Spatial resolution is a measure of the scale of the smallest feature able to be detected on an image, which is closely related to the pixel size of the image. In terms of pixel size, the spatial scale of remotely sensed data have been categorised into:

  1. Fine < 5m
  2. Medium 5 m - 100 m
  3. Coarse >100 m

Spectral resolution

This refers to the wavelength intervals (types of light) in which data are collected. Spectral resolution controls the information which can be derived from image data.

  1. High (hyperspectral, Greater than 20, narrow spectral bands (< 20nm) )
  2. Medium (multispectral, 3-20, broad spectral bands)
    Medium designed for land application (2-8 broad spectral bands (60-100 nm))
    Medium designed for coastal and Ocean water (8 to 15 broad spectral bands (5-20 nm))
  3. Low (panchromatic, analog or digital images) (1 band or true or false colour with 3 to 4 spectral bands (60-100 nm)

Radiometric resolution

Radiometric resolution defines the sensitivity or precision of the imaging sensor and is a quantitative measure of the level of variation in reflected light able to be detected by the sensor. The higher the radiometric resolution, the more detailed changes in reflected light able to be measured. As radiometric resolution is increased more detailed changes in reflected light are able to be measured.

Temporal resolution

Pertains to time image data are collected (AM or PM) and the frequency at which images are collected over a site.

  1. Extremely high - multiple daily
  2. High - daily
  3. Medium – weekly
  4. Low – < monthly, seasonally or yearly