What is Remote Sensing and Photogrammetry

Remote sensing as a science exploits, in one way or another, the use of the electromagnetic spectrum to “sense” an object and derive information from it.

The field of remote is a relatively young science and covers a very wide field of scientific methods of extracting information from “remotely” sensed data. The data can range from information extracted from satellite images to images from electron microscopes. Images can be captured on photographic material or digitally, via digital sensors, for interpretation on a computer.

Our daily lives are affected by remote sensing where it has been used to make our cars safer, determine daily weather broadcasts and its use in medicine with ultra sound, x-rays, CT and MNR scans etc.

A definition of remote sensing as a science and an art is thus as follows: - Remote sensing methods are any methods where information/data is extracted or interpreted by indirect measurement of the object under study (I.e. there is no physical contact with the object). The information is obtained via electromagnetic radiation (E.g. Light or Radar) and has been reproduced on film, paper or in digital format, from which the information/data is then extracted and interpreted.

Modern scientists use the term “remote sensing” with specific reference to remote sensing via satellites from which environmental or other information has been gathered by the plethora of manmade satellites that orbit the earth or other planetary missions. E.g. Mars missions

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By definition photogrammetry refers to any measurements taken using photographs as the prime non contact medium. This could be analog or digital format photography. Pigeons were used in the early days to collect photographs.

Branches of photogrammetry

There are two broad based branches in photogrammetry

  • Metric Photogrammetry : Deals with the precise measurements and computations on photographs regarding the size, shape, and position of photographic features and/or obtaining other information such as relative locations (coordinates) of features, areas, volumes, These photographs are taken using a metric camera and  is mostly used in the engineering fields e.g. surveying etc
  • Interpretive Photogrammetry: Deals with recognition and identification of the photographic features on a photograph such as shape, size, shadow, pattern etc to add value and intelligence to information seen on the photograph(annotation).

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