HOME ENV510 Landscape Ecology and GIS

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How does RS work?

Electromagnetic energy (eg light from the sun) illuminates objects on the Earth's surface. As it does this some energy is absorbed by the object, some is transmitted through the object, some is emitted by the object and some is reflected back from the object. Emitted and reflected energy can be detected by sensors.

Energy detection

• The most common sensor is the photographic camera. In this case, light sensitive film records reflected light energy in the form of black and white or colour images.
  
  
• Multi-spectral scanners are used to record visible light electronically as digital images. Scanners can also detect non-visible energy eg thermal infrared (to detect heat) and ultra-violet energy (to detect materials such as oil on the sea surface).Examples of multispectral scanners include Landsat and Spot.
  
  
• Meteological satellites e.g. NOAA
  
  
• Radar systems make use of microwave energy and generate images from the reflected signals. Radar scanners have the advantage of being able to see through cloud cover. e.g. Synthetic Aperture Radar (SAR) or Side Looking Airborne Radar (SLAR).
  

SPOT satellite

Thematic Mapper satellite

Multi Spectral Scanner satellite

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