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The sensors onboard remote sensing platforms record energy transmitted as electromagnetic radiation. The sensors contain detectors to record specific wavelengths within the Electromagnetic Spectrum (EMS). In remote sensing terminology, portions of the EMS are often called bands, or spectral bands [See Figure 1].
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 meter) As electromagnetic radiation moves from one medium to another it can be reflected, absorbed, transmitted, or refracted. Different types of land cover absorb and reflect different portions of the electromagnetic spectrum.
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