BASICS OF REMOTE SENSING
Introduction : -
Remote sensing obviously implies sensing from distance .It is nothing but an extension of an eye, it is generally understood to imply the acquisition of information about object/phenomena by scientific means or devices called sensors without there being any physical contact between any sensor and object. “Remote Sensing refers to the sensing or detection of electromagnetic radiation (E.M) which are reflected/scattered or emitted by an object.” The term Remote Sensing was given by Ewlyn L. in 1960.He was a geographer. The first aerial photograph in the history was given by Fellin Tournachone nick named Nadar, when he used a balloon to photograph the Paris Suburb Prtit, on a sunny autumn day 1858.
Remote Sensing System: -
Remote Sensing has essentially come to be exploited for inventory mapping &monitoring of earth resources .The information so generated is extremely important for resources managers & decision makers. Major elements are: -
2.Data processing &analysis
Data acquisition process: -
Source of energy
Energy in EM radiation
Propagation of radiation through earth station
Sensors (Active &Passive)
Platform (Air borne, Space borne & Ground borne)
Recording of Sensors either in picture form or electronically, numerical form 5
Transmission of data in India: -
Shadnagar , Hyderabad
MCU (Master Control Unit) at:-
Data processing and analysis involves following: -
Conversion of electronic data into pictorial form of computer compatible tapes (ccts). Acquisition of ground data comprising ancillary information and spectral signature to save a reference data. 2.
interpretation of data using interpretation devices or computer making use of reference data. 3.
Ground checks or evaluation of data.
generating information products for the user in form of maps, tables, picture and reports to act them in their decision making process in the management of various earth resources.
Eg:-land use and land cover
Electromagnetic Spectrum: -
The E. M. Spectrum is defined as of the E. M. radiation as according to frequency,
Wavelength energy, the true reasons that are currently being exploited are: - 6
Optical region (wavelength 300nm to 1500 nm)
Microwave region (1mm to 1m)
Optical region of E.M. spectrum: -
The portion of E.M. spectrum extending in wavelength from 0.3 to 15 micrometer is
Known as Optical region. This is the region in which all the objects on the surface of the
earth, under natural conditions, either reflect incident solar radiations or emit radiations
as a function of their temperature and molecular structure .Thus the radiation sensed in
this region being predominantly the solar radiation reflected off the object, the region is
called reflective region. It has 3 sub-regions:-
Ultra violet region (0.3 to 0.4 micrometer)
Visible region (0.4 to 0.7 micro meter)
Reflective or Solar infrared region (0.7 to 3.0 micrometer)
The wavelength from 0.3 to 0.9 micrometer is often term as photographic band as it is
detected by photograph.
The portion of infrared band from 0.7 to 0.9 micrometer is called photographic infrared because photograph film sensitive to this wavelength region is available.
Energy recorded into 3 to 15 micrometer portion of spectrum is mostly due to emission from an object as a result of its thermal activity which is the function of their temperature & emissivity of the object.
Microwave region of E.M. Spectrum:-
This region comprising of the wavelength from 1mm to 1m is termed as microwave...
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