Remote sensing is a technology of acquiring information about the earth’s surface and actually being in contact with it. This is done by sensing and recording reflected or emitted energy and processing, analyzing, and applying that information.
The science and art of acquiring information about an object without entering in contact with it, by sensing or recording the reflected or emitted energy and processing analyzing, and applying that information is remote sensing.
Remote means away from or at a distance, while sensing means detecting a property or characteristics. Thus, the term remote sensing refers to the examination, measurement, and analysis of an object without being in contact with it.
Remote sensing is broadly defined as collecting and interpretation information about a target without being in physical contact with the object. Aircraft and satellites are the common platforms for remote sensing observations. The term remote sensing is commonly restricted to methods that employ electromagnetic energy (such as light, heat, and radio waves) as the means of detecting and measuring target characteristics. This definition of remote sensing excludes electrical, magnetic, and gravity surveys that measure force fields rather than electromagnetic radiation. Magnetic and radioactivity surveys are frequently from aircraft but are considered airborne geophysical surveys rather than remote sensing.
Thus ‘ Remote sensing is the practice of serving information about the earth’s land water surfaces using images acquired from an overhead perspective, using electromagnetic radiation in one or more regions of the electromagnetic spectrum, reflected or emitted from the earth’s surface.
Remote sensing is the securing of data about an object or phenomenon without connecting with the object. Hence, it is in contrast to an on-location perception. The term is applied particularly for obtaining information about the Earth. Far-off remote sensing is in use in various fields. Fields include topography, land reviewing, and most Earth science disciplines. For instance, hydrology, nature, meteorology, oceanography, glaciology, and geography. It likewise has military, knowledge, business, monetary, arranging, and philanthropic applications.
Remote sensing is defined, for our purposes, as the measurement of object properties on the earth’s surface using data acquired from aircraft and satellites. It is, therefore, an attempt to measure something at a distance rather than in situ. While remote-sensing data can consist of discrete point measurements or a profile along a flight path, we are most interested here in measurements over a two-dimensional spatial grid, i.e., images. Remote sensing systems, particularly those deployed on satellites, provide a repetitive and consistent view of the earth that is invaluable to monitoring the earth system and the effect of human activities on the earth (Schowengerdt, 2006).
What is Remote Sensing?
Remote Sensing is an innovation to assemble data and dissect an object or phenomenon without connecting. This innovation is utilized in various fields like topography, hydrology, environment, oceanography, and many more.
A geographic data framework is an instrument that is in use for planning and breaking down component occasions on Earth. The far-off detecting and GIS innovation consolidate significant information base activities like measurable investigation and inquiry, with maps.
In current use, the word remote sensing generally for the most part alluding to the utilization of satellites. Even used in airplane-based sensor advances to distinguish and group protests on Earth. It incorporates the surface and the air and seas, in view of spread signs. For example, electromagnetic radiation. It very well might be part of “active” distant detecting when a sign is transmitted by a satellite or airplane to the item and its appearance distinguished by the sensor and “passive” far off sensing when the impression of daylight is identified by the sensor.
Some definitions of Remote Sensing
Remote sensing is the science and are of obtaining information about an object, area, or phenomena through satellite.
According to Lillesand and Kilfer- “The science and are of obtaining information about an object, area, phenomena (earth surface) through the analysis of data acquired by a device that is not in direct contact with the object, area, phenomena under the investigation.”
There are many possible definitions of what remote sensing actually is. One of the most accepted definitions of remote sensing is that it is the process of collecting and interpreting information about a target without being in physical contact with the object. Aircraft and satellites are the common platforms for remote sensing observation.
According to the United Nations, “The term remote sensing means the sensing of the Earth’s surface from space by making use of the properties of the electromagnetic wave emitted, reflected or diffracted by the sensed objects, for the purpose of improving natural resource management, land use and the protection of the environment.”
Advantages of Remote Sensing
The basic advantages of remote sensing are listed below:
1. A relatively cheap and rapid method of acquiring up-to-date information over a large geographical area.
2. It is the only practical way to obtain data from inaccessible regions, e.g., Antarctica, and Amazonia.
3. At small scales, regional phenomena which are invisible from the ground are clearly visible (e.g., beyond man’s visibility); for example, faults and other geological structures.
4. Cheap and rapid method of constructing base maps in the absence of detailed land surveys.
5. Easy to manipulate with the computer and combine with other geographic coverage in the GIS.
Disadvantages of Remote Sensing
The basic disadvantages of remote sensing are given below:
1. They are not direct samples of the phenomenon, so they must be calibrated against reality. This calibration is never exact; a classification error of 10% is excellent.
2. They must be corrected geometrically and georeferenced in order to be useful as maps, not only as pictures.
3. Distinct phenomena can be confused if they look the same to the sensor, leading to classification errors – for example, artificial and natural grass in green light.
4. Phenomena that were not meant to be measured can interfere with the image and must be accounted for.
5. Resolution of satellite imagery is too coarse for detailed mapping and for distinguishing small contrasting areas.