THE SCIENCE

Satellite remote sensing is the name given to a host of activities designed to gather data and information about the Earth's surface without actually being in contact with it. This is done by using space-borne sensors to measure energy reflected or emitted by surface features and then to process this data into imagery from which information can be visually interpreted.

A common misperception about these satellites is that they take photographs from space like a camera. Although there are some similarities between the sensors in these satellites and a digital camera, the actual process of interpreting satellite data is far more complicated. Whereas a digital camera records the brightness of a scene over a broad range of wavelengths corresponding to red, green, and blue light - satellites have one set of sensors for each of these very specific wavelengths. This precision enables scientists to distinguish different vegetation and mineral types as well as other types of land use by the ways in which these materials reflect or emit light. This same precision makes it possible for artists to produce colorful images by applying the same image processing techniques.

To produce an image that can be printed on paper/canvas or viewed on a monitor, this information must be mathematically manipulated to give just three values for each pixel. These values are determined by the primary colors that all other colors originate from - red, green and blue (RGB).