Page 9 - RemoteSnsing&GIS by PK Gogoi
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 .  Transmission,  Reception,  and  objects in the nature and obviously we see different colours . Just  n  electromagnetic  radiation,  two
 think for a while and thank God for giving us Sensors of special
 5Processing (E) - the energy recorded by                    Icharacteristics are particularly important for
 kinds-Eyes,Nose,Ears
 the sensor has to be transmitted, in binary form
 Fig 2 : Remote Sensing Process
 of digital numbers, usually 0 to 9. These
 receiving and processing stations processe the

 digital information to pictorial form or in  o far we have discussed about the very
 image.         Sbasic concept and terminology of

 I I) Data Analysis  Remote Sensing. Every element of remote
            sensing process is essential . These elements
 . Interpretation and Analysis (F) - The
            play a pivotal role in receiving information
 6processed image is interpreted, visually
            from the earth in order to survey specific area or
 and/or digitally or electronically, to extract
            field of interest on the subject matter of       Fig 2: Radiation of sunlight with
 information about the target which was
            physical    ,topography,soil,climate,hydrology   EMR spectra.
 illuminated. This procedure is known as image
            ………etc. Following are the conceptual basis
 processing or image classification                               he EMR consists of wavelength and
            of understanding     of the remote sensing
 . Application (G) - The final element of                    Tfrequency. The wavelength is the length of
            processes.
 7the remote sensing process is achieved                     one wave cycle, which can be measured as the
                . Energy Source or Illumination and          distance between successive wave crests.
 when we apply the information we have been
            1Radiation          principles      (A)      :   Wavelength is usually represented by the Greek
 able to extract from the imagery about the
            Electromagnetic Radiation(EMR). First and        letter lambda (λ). Wavelength is measured in
 target in order to better understand it, reveal
            foremost,there has to be radiant energy source   meters (m) or some factor of meters such as
 some new information, or assist in solving a
            for remote sensing to illuminate the target . In a  nanometres (nm, 10-9_meters), micrometers
 particular problem. In the figure, it has depicted
            Passive Remote Sensing, the source is the Sun    (µm, 10-6 meters) or centimeters (cm, 10-2
 the process of Remote sensing in which
            and have its light energy radiating from the Sun  meters). Frequency refers to the number of
 information of the earth is received by sensors
            to the Earth in the form of shortwave solar      cycles of a wave passing a fixed point per unit
 following a sequential and detailed procedure.
            radiation. This shortwave incoming solar         of time. Frequency is normally measured in
 n the next chapter a detailed explanation of
            energy is in the form of electromagnetic         hertz (Hz), equivalent to one cycle per second,
 Ithese essential processes one by one will
            radiation. All electromagnetic radiation is a    and various multiples of hertz. In the wave
 definitely help us to understand the subject in a
            combination of electric wave, symbolised as      theory it denotes c= fλ , where c = speed of light
 lucid manner .
            the word ‘E’ and magnetic waves as ‘M’.          (3x 10-8 mt/sec) ; f (nu)= number of waves in
            Following the basic rule of wave theory, both    unit time ,usually expresses in Hz(hertz) ; λ
 Remote Sensing is a process of getting information without
            the waves bisects each wave at right angles and  (lamda) is wavelength(nm).It is now apparent
 any direct contact with any object or things. Viewing anything over
 the earth by us is an example of remote sensing because the  travels(propagates)forward at the  speed of  that wavelength of radiation is inversely
 beautiful nature being looked at by us through our eyes is nothing  light(c).The  diagrammatic  view  of  the  proportional to the frequency, meaning lower
 but the reflection of light from objects. Whenever we see some
            electromagnetic wave is shown in the figure to   the wavelength, higher will be the frequency
 colour (say, white) it means all part of visible rays consisting of
 seven colours is reflected ,hence nothing is absorbed by the object  understand better. It is denoted as EMR for  and( molecular) energy and vice versa. As has
 and we can see it white. Similarly, within the visible range of colour,  Electromagnetic Radiation.  been mentioned that earth’s resources always
 there are different shades of colour being reflected by the different
                                                                            Image/Diagram courtesy : Google image search engine
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