Significance of Remote Sensing and GIS.

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 A]  What is meant by Remote Sensing?



  • Remote Sensing is a process of collecting information of an object with the help of Electromagnetic Radiation from a particular distance in space, without being in direct physical contact with the object.
  • The information is recorded by various sensors attached to the platforms established at great distance in space.
  • These sensors record the reflected and radiated electromagnetic energy from various features on the Earth's surface.
  • Further, the recorded information is used to form images and maps.
  • For a remote sensing system to work, sensors, cameras, platforms, etc. are required in order to collect, transmit and analyze the recorded data.

B]  Sensors and Platforms:

  • Remote Sensing platforms can be defined as the structures or vehicles on which remote sensing instruments are mounted.
  • Typical platforms are satellites and aircrafts, but they can also include radio- controlled airplanes, balloon kits for low altitude remote sensing, as well as ladder trucks or cherry pickers for ground investigation.
C]  Types of Platforms:

a)  Ground Borne Platforms:
  • These are used to record detailed information about the surface which is compared with information collected from aircrafts or satellite sensors for ground based observation. 
  • These include hand- held cameras, cranes, ground vehicles, tethered balloons, and even towers. 
b)  Air Borne Platforms:

  • Air borne platforms are used to collect very detailed images and facilitate the collection of data over virtually any portion of the Earth's surface at any time. 
  • Air Borne platform were the only non- ground based platforms for early remote sensing work.
c)  Space Borne Platforms:

  • In space borne remote sensing, sensors are mounted on board a spacecraft orbiting the Earth. Space borne or satellite platforms are cost intensive but have relatively lower cost per unit areas of coverage.
  • Space borne imaging are placed at an altitude of 25 km to 36000 km.


D]  What is Geographic Information System?



  • A Geographic Information System (GIS) is a system designed to capture, store, manipulate, analyze, manage and present spatial or geographic data.
  • GIS applications are tools that allow users to create interactive queries, analyze spatial information, edit data in maps and present the results of all these operations.
  • The first known use of the term ' Geographic Information System' was done by Roger Tomlinson in 1968 in his paper " A Geographic Information System for Regional Planning". He is also known as 'Father of GIS'.

E]  Spatial and Non- Spatial Data:

  • Spatial Data is usually stored as coordinates and topology and is data that can be mapped. 
  • The most common source of spatial data is topographical or thematic maps. 
  • Non- Spatial Data is data which gives information about the spatial data. 
  • It defines the various attributes of Spatial data.
  • It is also known as attribute data. For example, a table containing population information for specific locations such as city, districts or provinces. The population, though is non- spatial type, has relationship with locations.