The sensors onboard remote sensing platforms record
energy transmitted as electromagnetic radiation. The sensors contain
detectors to record specific wavelengths within the Electromagnetic
In remote sensing terminology, portions of the EMS are often called
bands, or spectral bands [See Figure 1].
Figure 1: The Electromagnetic
The Electromagnetic Spectrum is defined by wavelength.
It ranges from very short wavelength cosmic rays to the long wavelength
of standard radio waves. Typical aerial photography and infrared
aerial photography are taken in the visible and photographic infrared
bands, which range from 0.4 to 0.9 micrometers. (millionths of a
As electromagnetic radiation moves from one
medium to another it can be reflected,
Different types of land cover absorb and reflect different portions
of the electromagnetic spectrum.