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Remote Sensing techniques for Agriculture suvey
The given sensor system of camera are in agricultural survey.
- Photographic cameras
The photographic system, having conventional camera with black and white photography, is the oldest and probably, so far, the most widely used sensor for recording information about ground object. Photographic cameras have been successfully used in aircraft platform remote sensing. In this system, the information is limited to size and shape, as the films used are sensitive only to visible region of spectrum. The response of black & white films is about 0.4-0.7 mm for infrared imagery, films with response extending up to 0.9 mm are available.
- Return Beam Vidicon (RBM)
This is very similar to a television camera. In such a system, a fixed camera lens on a photosensitive semi-transparent sheet forms the ground image. This image is created on the surface as electrical change or potential.
The TV cameras are the best example of high resolution, operated in space for resource survey was the RBV used in LAND SAT series. On LAND SAT I, II and III RBV cameras were used, each corresponding to a different wavelength band 0.475-0.585 mm (green), 0.580-0.690 mm (red) and 0.690-0.830 mm (near infrared). The Indian experimental remote sensing satellite, Bhaskara-I and II carried a two-band TV camera system, Multispectral imagery was produced in LAND SAT and Bhaskara by using separate camera tubes of each band and selecting the spectral band with appropriate filters.
- Optical-mechanical scanners
This imaging system has the advantage that any set of desired spectral bands can be selected with appropriate filter and detector combinations. The mostly widely used sensor in this category is the MSS on LAND SAT series. MSS has four spectral bands, covering form 0.5-to 1.1 mm region. MSS operates on the principle of scanning successive lines at right angles to the flight path by means of a rotation or oscillating optical system. The radiation levels along the lines are recorded by appropriate sensor elements. When used in the visible band, the collected light can be split by the optics and separately filtered and recorded, giving simultaneous multispectral recording from the one instrument. MSS can record in any part of ultraviolet to near IR window. They are use also in the thermal IR windows
- Radar and Microwave sensors
The acquisition of data in microwave region has been possible since 1950s but its application to natural resources is considerably less developed, as compared to the visible and IR image interpretations. Microwave sensors have distinct advantages because they are unaffected by atmospheric conditions and are thus able to penetrated smoke, clouds, haze and snow. Under this system, Plan Position Indicator (PPI), Side Looking Air borne Radar (SLAR) and Synthetic Aperture Radar (SAR) can be grouped. These systems offer day and night as well as all weather capability and ability to penetrate a cover of vegetation.
- Advance remote sensors
Linear Imaging and Self Scanning Sensors (LISS) are the advanced imaging systems. This type of scanning sensor are used an array of solid-state devices. The array may be made of photo-diodes, phototransistors or Charge-Coupled Devices (CCDs). In the LISS, the optics focuses a strip of terrain in the cross-track into the sensor array. The image from each detector is stored and shifted out sequentially to receive a video signal. The SPOT (Satellite Probatorie d' Observation de la Terra) and IRS (Indian Remote Sensing Satellite) series carry such solid-state sensor systems, which are also known as push-broom scanners.
The IRS IC most advanced satellite, carries an improved sensor system. Besides carrying a sophisticated LISS-III camera, it has a Panchromatic camera (PAN) and a Wide Field Sensor (WiFS). The PAN has been designed to provide data with a spatial resolution of 5.8m in stereo mode, with a ground swath of 70km, whereas WiFS provides data in two spectral bands, with a spectral resolution of 188m and a ground swath of 180km.
The given wavelengths are employed in agricultural survey through Electromagnetic radiation by using remote sensor system.
Use of wavelength region for Agricultural survey
| Area of agricultural phenomena |
Wavelength employed |
1. Plant diseases and insect infestation
2. Natural vegetation, types of crop and fresh inventories
3. Soil moisture content (radar)
4. Study of arable and non-arable land
5. Assessment of plant growth and
rigour for forecasting crop yield
6. Soil type and characteristics
7. Flood control and water management
8. Surface water inventories, water quality
9. Soil and rock type and conditions favorable
for hidden mineral deposits.
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0.4-0.9 mm and 6-10 mm
0.4-0.9 mm and 6-10 mm
04-0.8 mm and 3-100 mm
0.4-0.9 mm
0.4-0.9 mm
0.4-1.0 mm
0.4-1.0 mm and 6-12mm
0.4-1.0 mm and 6-12 mm
0.4-1.0 mm and 7-12 mm
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Generally the remote sensing devices operate in the green, red and near infrared regions of the electromagnetic spectrum for agriculture and other allied phenomena. Agricultural resources can be obtained by measuring spectral, spatial and temporal variations of electromagnetic radiation emanating from points of interest and then analyzing these measurements to relate them to specific classes of agricultural phenomena purpose. Spectral variations are changes in the intensity of radiation at a given wavelength i.e. difference in colour. Spatial variations are changes in radiation from one location to another i.e. difference in shape and position. Temporal variations are changes in radiation from one time to another i.e. difference over time. One of the most successful applications of multispectral space imagery (sensor) is monitoring the state of the world's agricultural production. This application includes and differentiation of the agricultural phenomena.
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