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Remote Sensing techniques for Agriculture suvey


Electromagnetic Remote Sensing Process
Agricultural resources data are collected y aircraft and satellite-mounted instruments, which receive reflected energy from target in some frequency of the electromagnetic spectrum. The process involved in electromagnetic remote sensing system namely, data acquisition and data analysis are outlined below and a schematic diagram of electromagnetic remote sensing process in shown in the Fig. 2

Data acquisition
The data acquisition process comprises of the following distinct elements, which are necessary in agricultural survey
  • Energy sources
  • Propagation of energy through the atmosphere
  • Energy interactions with earth's surface features
  • Air borne/Space borne sensors to record the reflected energy
  • Generation of sensor data in the form of pictures or digital information
Data analysis
The data analysis process involves examining the data using various viewing instrument to analyze pictorial data, which is called the visual interpretation technique and computer to analyse digital data, a process known as digital analysis.

Reference Data
Reference data also called ground truth area an essential part of remote sensing data processing. It is used to analyse and interpret remotely sensed data, to calibrate a sensor, and to verify information extracted from remote sensing data.

The above given figure-3 shows the part of the spectrum relevant to remote sensing. The most common form of remote sensing was Aerial photography, in which used the visible light section of the electromagnetic spectrum. Newer sensors can acquire data in this and other sections of the electromagnetic spectrum, such as the non-visible infrared and near infrared wavelength, as will as microwaves used for radar. Many of these sensors can acquire several section of the spectrum concurrently and may be termed multispectral scanners. The electromagnetic wavelength bands with their bands with their utility in remote sensing are described in the given table -1


Table 1 Electromagnetic spectral region

Advantages of Remote Sensing techniques in Agricultural survey
With the primary aim of improving the present means of generating agricultural data, a number of specific advantages may result form the use of remote sensing techniques.
  1. Vantage point
    Because the agricultural landscape depends upon the sun as a source of energy, it is exposed to the aerial view and, consequently, is ideally suited or remote sensing techniques.


  2. Coverage
    With the use of high-altitude sensor platforms, it is now possible to record extensive areas on a single image. The advent of high-flying aircraft and satellites, single high quality images covering thousand of square miles


  3. Permanent record
    After an image is obtained, it serves as a permanent record of a landscape at a point in time which agriculture changes can be monitored and evaluated.


  4. Mapping Base
    Certain types of remote sensing imagery are, in essence, pictorial maps of the landscape and after rectification (if needed), allow for precise measurement (such as field acreages) to be made on the imagery, obviating time-consuming on the ground surveys. These images may also aid ground data sampling by serving as a base map for location agriculture features while in the field, and also as a base for the selection of ground sampling point or areas.


  5. Cost savings
    The costs are relatively small when compared with the benefits, which can be obtained form interpretation of satellite imagery.


  6. Real-time capability
    The rapidly with which imagery can be obtained and interpreted may help to eliminate the lock of timeliness which plagues, so many agricultural survey.


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