REMOTE SENSING & GIS

• THE AGE OF MODERN CARTOGRAPHY•
            ( Remote Sensing & GIS)
In the 20th century, the invention of the airplane followed by satellite remote sensing technology added a new dimension to mapping and widened its scope through the method of remote sensing. This provided a bird's eye view of the Earth and save time and money required for conventional surveying of ground realities.
In the broadest sense,remote sensing is the measurement or acquisition of information of an object or phenomenon, by a recording device that is not in physical or intimate contact with the object. It is the utilization at a distance (as from aircraft, spacecraft, satellite or ship) of any device for gathering information about the environment. The techniques can make use of devices such as a camera,laser,radar,sonar,seismograph, or a gravimeter. Modern remote sensing normally includes digital processes but can be done as well with non digital methods.

Aerial photography is the original from of remote sensing. An aerial photograph can be defined as a photograph taken from an aircraft with a camera specially designed for aircraft use. The occurrence of the two world wars led to a demand for aerial photography for military purposes. In India, aerial photographs have been in use since 1920 for areal survey and for interpretation of specific fields such as topological mapping, geology, engineering, environmental studies, and exploration of oil and minerals.

With the development of satellite technology between 1970 and 1980, remote sensing through satellites received more attention from researchers, cartographer and general users. An image taken from space using a spacecraft as a platform and scanners or specially designed cameras as sensor to detect the given area of the earth's surface is termed satellite imagery.
The remote sensor system makes use of the emitted or reflected electromagnetic radiation of the examined object and measures a larger area of the Earth.
Satellite imagery can be widely applied and is extensively used by scientists, researchers, and planners in map making, urban and regional planning, agriculture, forestry,ecology and environment,soil survey, natural resource mapping, oil and mineral exploration, and so on.
In traditional cartography, the map represented both the data base and the display of geographic information whereas in GIS (Geographical Information System),the database,analysis, and display are physically and conceptually separate aspects. Geographic Information system include several elements such as computer hardware,software, digital data,people and institutions for collecting, starring,retrieving, analysing and displaying georeferenced data or information about the Earth. Modern Mao making relies much more on GIS,which provides flexible computer - aided database and maps.