Spectral band
Also called: Band · Topic: Remote Sensing, GIS and GNSS · NCERT: Class 11, Ch 6 "Introduction to Remote Sensing"
Meaning
A spectral band is one chosen range of wavelengths that a sensor records. Examples are green (0.5 to 0.6 micrometre), red (0.6 to 0.7 micrometre) and near infrared (0.7 to 1.1 micrometre). A multispectral sensor records several bands separately, one image for each band. Surfaces look different from band to band, so comparing bands helps tell features apart. Narrower bands, and more of them, mean better spectral resolution.
Example
In NCERT's Resourcesat-1 images of Najafgarh, Delhi (2005), dry surfaces look bright in band 2 (green) because they reflect it. Fresh water looks dark in band 4 (infrared) because it absorbs it.
Don't confuse with
- Spectral signature: a band is a single wavelength range. A signature is an object's whole pattern of reflectance across many bands.
Related concepts
- Electromagnetic radiation
- Electromagnetic spectrum
- Near infrared
- Atmospheric absorption and scattering
- Thermal infrared remote sensing
- Reflectance
- Absorptance
- Spectral signature
- NDVI