What is the principle and uses of remote sensing

Upendra Kumar

                                       Principles Of Remote Sensing

Remote Sensing:- Remote Sensing has been defined as the science and art of obtaining information about an object, area, or phenomenon through the analysis of data acquired by the device that is not in physical contact with the object. area or phenomenon through the analysis of data acquired by the device that is not in physical contact with the object, area or phenomenon under investigation.

In remote sensing, the object should be located on or near the earth's surface and the sensor should be more or less above the object at a substantial distance from the object.

CLASSIFICATION OF REMOTE SENSING SYSTEM:-Remote Sensing System can be classified on the basis of many different criteria.

1. Active and Passive system:- An active system is a remote sensing system that transmits its own electric magnetic emanations at an object and then records the energy reflected or refracted back to the sensor. A passive system is a sensing system that detects or measures radiations emitted or reflected by the target.

Active and Passive system

2. Photographic or scanning system:- In the photographic system, a photograph formed by the action of light on a base material coated with a sensitized solution that is chemically treated to fix the image points at the desired density is used for further analysis. The photographic system, however, operates over a narrow wavelength band from 0.3 to 0.9 𝝁m. They nevertheless produce relatively cheaply an image which is of high geometric fidelity and resolution. Scanning systems use scanners to make use of infrared radiation (wave band 3 to 4 𝝁m) and microwave radiation (wave band 5 to 500 mm).

                 

3. Aircraft or Satellite bassed:-

                                                         Aircraft

Drone Survey

If the sensor platform is an aircraft it is called an aircraft based remote sensor. Aerial photography from the aircraft is the first method of remote sensing. It came during world war I and II. In the world war, it was used to identify plot enemy position, Topographic mapping from the stereoscopic aerial photograph. After 1945 improved the resolution of lenses now it is used for topographic mapping to application in Civil engineering, Mining engineering, Geology, Agriculture, Forestry, Archeology, etc.

It is the most popular because it has the following advantage.

Availability: -Photographs are readily available for parts of the world, Where aerial surveying has been carried out.

Economy:-Aerial photographs give information more cheaply than those obtained from field surveys.

Synoptic viewpoint:-Aerial photographs enable detection of small scale features and spatial relationships that would not be evident on the ground.

Time freezing ability:-An aerial photograph records the earth's surface which is used for the historical records.

Spectral and spatial resolution:-An aerial photograph is sensitive to radiation in wavelengths that are outside the spectral sensitivity range of the human eye. It can sense ultraviolet (0.3 to 0.4 𝝁m) and near-infrared( 0.7 to 0.9 𝝁m) radiation.

Three-dimensional perspective:- A stereoscopic view of the earth's surface can be created and measured both horizontally and vertically.

                                        NON PHOTOGRAPHIC SYSTEM (SCANNERS)

In the Scanning system, the data of the object recorded automatic and digital form and process in computer control. it also scans the object 2D and 3D mode at different angles.

  

                  

The various type of sensors used in the scannig system.

i. Multispectral scanners

ii. Thermal infrared scanners

iii. Passive microwave scanners

Satellite Remote Sensing

Satellite remote sensing is satellite-based. It is used in the land application. The advantage of satellite remote sensing to take less time to scan. For example, Landsat thermic mapper, image a scene 170 km x 155 km in 25.87 seconds.

Satellites are grouped in the following ways.

i. From the function point of view:- Earth resources satellites are used for applications in land use. They carry sensors with a medium spatial resolution of 0.25 km and have a fast repeat cycle of less than a day.

ii. From the orbit, they follow:- The polar orbit is a low earth orbit where satellites fly at 200 to 1000 km altitude. The orbit takes the satellite over or near the north and south poles and the orbit is in the plane of the sun or sun-synchronous that is the orbit remains in a constant plane in relation to the sun, while the earth spins below.

Uses of remote sensing

1. METEOROLOGY:-Profiling of atmospheric temperature, pressure, water vapor content, and wind measurement.

2.Oceanography:-Measurement of sea surface temperature, Mapping ocean currents, and wave energy

spectra.

3. Glaciology:-Mapping the distribution and motion of ice sheets, determining the navigability in the sea.

4.Geomorphology, Geology:- Identification of rock types, location of geological faults and anomalies, measuring the figure of the earth, and observing movements.

5. Topography and cartography. Obtaining accurate elevation data and referring to given co-ordinate system, production, and revision of maps.

6. Agriculture, forestry, botany etc. Monitoring the extent and type of vegetation, soil mapping.

7. Hydrology.

8. Disaster Control.

9. Planning applications.

10. Military application.

See also:-

what is drone survey

The Use of 3D Laser scanning Technology in Mining and Surveying