A technology used to collect data about an object, place, or phenomenon without any actual physical contact with it is known as remote sensing. It is the method of detecting and scanning the physical characteristics of an object, place, or phenomenon by measuring the reflected and emitted radiation from it at a distance (generally with the help of a satellite or an aircraft).

Read on, to understand more about remote sensing, its components, types, principles, and what are the uses in the field of science and research along with some FAQs.

Remote Sensing

Remote Sensing is a technology that is used to collect information and examine an object, place, or phenomenon without making any physical contact with it. It is used in several fields like geography, geology, ecology, glaciology, hydrology, and oceanography. Special cameras present collect remotely sensed pictures, which helps the researchers “sense” the things about the Earth and other planets. Remote sensing when combined with GIS technology helps in important database operations like queries with maps, and statistical analysis.

This technology started with the invention of the camera. Initial photographs were just simple photographs, but the intention of taking the Earth’s images for its graphic mapping arose during the year 1840 and due to this concept scientists started to fix cameras on balloons just to take a wide range of images. During the era of WWI, cameras were placed on airplanes just to get an aerial view image of landslides. Only during the space age era did satellite remote sensing develop. It was used for the objective of imaging the Earth’s surfaces as well as sensing other spacecraft, and other planets.

Components of Remote Sensing

Platform

It can be defined as the carrier for remote sensing sensors. There are three main remote sensing platforms, which are mentioned below:

1. Ground-level platforms – Like cranes and towers
2. Aerial platforms – Like helicopters, high altitude aircraft, and low altitude aircraft.
3. Spaceborne platforms – Like space shuttles, geostationary satellites, and polar-orbiting satellites.

Below is an image showing different types of platforms used in remote sensing.

Sensors

It is a device that is used to receive electromagnetic radiation from different objects and surfaces and convert them into a signal that can be recorded and exhibited, either in the form of numerical data or in the form of an image.

There are also many elements involved in the functioning of remote sensing, which are mentioned below:

1. Source of energy (A)
2. Radiation of a source of energy in the atmosphere (B)
3. Interaction of radiation with the object (C)
4. Recording of the energy by a sensor (D)
5. Transmission, Reception, and Processing of the radiation (E)
6. Interpretation and analysis of the radiation by the sensor (F)
7. Application of that radiation (G)

Below is an image showing all the elements involved in remote sensing.

Types of Remote Sensing

There are mainly two types of sensors used, which are as mentioned below:

Active Remote Sensing

Active remote sensing utilizes an artificial source of radiation as an investigation, and the resulting signal, which scatters back to the sensor, depicts the Earth or the atmosphere.

The Synthetic-Aperture Radar system is a type of active sensor, which can emit radiation in the form of a beam coming from a moving sensor and can also measure the backscattered components returning to the sensor from the ground in the region of the microwave.

Passive Remote Sensing

Passive remote sensing depends only on solar radiation as its source of energy, which can be seen in multispectral, and hyperspectral sensors. It is mainly concentrated in the visible, near-infrared, and shortwave infrared spectral regions.

These sensors at the satellite measure the emerging radiation from the surface of the Earth’s atmosphere system in the direction of sensor observation. In a remote sensing image, a grid of pixels is located to achieve image sensing by a combination of scanning in the cross-track direction and the sensor platform movement along the in-track direction.

Principles of Remote sensing

The principles of remote sensing involve detection and measurement of the radiations of different wavelengths which are reflected or emitted from the surface of distant objects or materials, which helps in their identification and categorization.

It has four basic components to measure, which include:

1. Energy source
2. Transmission path
3. Target
4. Satellite sensor

Among these components, an energy source which is also known as electromagnetic energy play a very important role. As it fulfils a significant medium for transmitting the information from the target to the sensor. It can also be described as an electromagnetic spectrum on which many forms of energy exist which can be described as different types of energy in a specific region of the spectrum.

This spectrum includes visible light, radio waves, microwaves, heatwaves, infrared ways, UV rays, X-rays, and gamma rays. It is also a synopsis of the continuum of electromagnetic waves and energy from extremely short wavelengths like cosmic gamma rays to extremely long wavelengths like in television and radio waves. It should always be kept in mind that these divisions are not absolute and definite as overlapping can occur.

Relying on the wavelength and the insignificant spectral location, principle applications can be approximated with suitable satellite bands for the classification.

Uses of Remote Sensing

1. 1. • It is used to analyze the condition of roads in rural areas.
      • Also it is used to compute snow packs in the areas where it usually snows in winters.
      • It is also used to take Earth’s pictures from space.
      • Remote Sensing is used to control forest fires.
      • It is also used to detect the usage and cover of land.
      • It is used to create a base map for visual references.
      • Also it is also used for the estimation of forest supplies.
      • It is used to locate construction and altercations in a building.
      • It is used to observe climatic changes.
      • Remote Sensing is also used in predicting potential landslides.
      • It is also used to identify the condition of a crop.
      • Also it is used to determine the soil moisture content.
      • It is also used to analyze the health of a crop.
      • It is used to monitor drought in crop areas.

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