Remote sensing: principles, electromagnetic spectrum, components and applications

Remote sensing, also called earth observation, refers to obtaining information about objects or areas at the Earth’s surface without being in direct contact with the object or area. Humans accomplish this task with aid of eyes or by the sense of smell or hearing; so, remote sensing is day-today business for people. Reading the newspaper, watching cars driving in front of you are all remote sensing activities. Most sensing devices record information about an object by measuring an object’s transmission of electromagnetic energy from reflecting and radiating surfaces.

Principles of remote sensing

Detection and discrimination of objects or surface features means detecting and recording of radiant energy reflected or emitted by objects or surface material. Different objects return different amount of energy in different bands of the electromagnetic spectrum, incident upon it. This depends on the property of material (structural, chemical, and physical), surface roughness, angle of incidence, intensity, and wavelength of radiant energy.

The Remote Sensing is basically a multi-disciplinary science which includes a combination of various disciplines such as optics, spectroscopy, photography, computer, electronics and Telecommunication, satellite launching etc. All these technologies are integrated to act as one complete system in itself, known as Remote Sensing System. There are a number of stages in a Remote Sensing process, and each of them is important for successful operation. Progressive stages in remote sensing are as follows:

Emission of electromagnetic radiation, or EMR (sun/self- emission)
Transmission of energy from the source to the surface of the earth, as well as absorption and scattering
Interaction of EMR with the earth’s surface: reflection and emission
Transmission of energy from the surface to the remote sensor
Sensor data output
Data transmission, processing and analysis

At temperature above absolute zero, all objects radiate electromagnetic energy by virtue of their atomic and molecular oscillations. The total amount of emitted radiation increases with the body’s absolute temperature and peaks at progressively shorter wavelengths. The sun, being a major Source Of Energy, radiation and illumination, allows capturing reflected Light with conventional cameras and films.

Electromagnetic radiation and Electromagnetic spectrum

EMR is a dynamic form of energy that propagates as wave motion at a velocity of c = 3 x 1010 cm/sec. The parameters that characterize a wave motion are wavelength (λ), frequency (ν) and velocity (c). The relationship between the above is:

c = νλ.

Electromagnetic energy radiates in accordance with the basic wave theory. This theory describes the EM energy as travelling in a harmonic sinusoidal fashion at the velocity of light. Although many characteristics of EM energy are easily described by wave theory, another theory known as particle theory offers insight into how electromagnetic energy interacts with matter. It suggests that EMR is composed of many discrete units called photons/quanta. The energy of photon is

Q = hc / λ = h ν

Where Q is the energy of quantum

h = Planck’s constant

Components of Remote Sensing System

Although, the remote sensing includes a wide array of technologies and types, but they all are based on certain common concepts with the same basic components. The basic components of remote sensing system are given below:

Target
Energy source
Transmission path, and

The target is the object or material being studied. All the components in the system work together, to measure and record the information about the target without making physical contact. The energy source illuminates or provides electromagnetic energy to the target.

The energy interaction with the target depends on the target properties and the radiation. It also acts as a medium for transmitting the information from target to the sensor. The sensor is a remote device to collect and record the electromagnetic radiation.

Sensors are also used to measure the given-off energy or emitted energy by the target; reflected-off energy of the target; or transmitted energy from the target. After recording of energy, the resulting set of data is transmitted to the receiving station.

At receiving station, the data is processed to a usable format, i.e., in the form of image. The image is then interpreted to extract the informations about target. The interpretation of image can be done visually or electronically with the help of computers and image processing softwares.

Remote Sensing Applications

Land Use Mapping

Remote sensing data is useful in obtaining up-to-date land use pattern of large areas at any given time and also monitor changes that occur from time to time. It can be used for updating road maps, asphalt conditions, and wetland delineation. This information is used by regional planners and administrators to frame policy matters for all-round development of the region.

Weather Forecasting

Remote sensing is extensively used in India for weather forecasting. It is also used to warn people about impending Cyclones-2/”>Cyclones.

Environmental Study

It can be used to study deforestation, degradation of fertile lands, pollution in Atmosphere, Desertification, eutrophication of large water bodies and oil spillage from oil tankers.

Study of Natural hazards

Remote sensing can be used to study damages caused by Earthquakes, Volcanoes-2/”>Volcanoes, landslides, floods and melting of ice in polar regions. Many times remote sensing will be helpful to predict the occurrence of natural hazards.

Resource exploration

Remote sensing data is helpful for updating existing geological maps, rapid preparation of lineament and tectonic maps, identifying the sites for quarrying the Minerals and helpful in locating fossil fuel deposits.

Remote sensing is the acquisition of information about an object or phenomenon, without making physical contact with the object. In other words, it is the process of obtaining information about an object or area from a distance.

Remote sensing can be used to collect data about a wide range of things, including the Earth’s surface, the atmosphere, and the Oceans. It can also be used to monitor changes over time, such as changes in land use or Climate change.

There are many different types of remote sensing, including optical remote sensing, radar remote sensing, and lidar remote sensing. Each type of remote sensing has its own advantages and disadvantages.

Optical remote sensing is the most common type of remote sensing. It uses visible and near-infrared light to collect data about the Earth’s surface. Optical remote sensing is relatively inexpensive and easy to use. However, it is not always possible to use optical remote sensing, such as when the sky is cloudy.

Radar remote sensing uses radio waves to collect data about the Earth’s surface. Radar remote sensing can be used in all weather conditions, including when the sky is cloudy. However, radar remote sensing is more expensive than optical remote sensing.

Lidar remote sensing uses light to collect data about the Earth’s surface. Lidar remote sensing is very accurate and can be used to collect data about the Earth’s surface in three dimensions. However, lidar remote sensing is the most expensive type of remote sensing.

The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The electromagnetic spectrum includes radio waves, microwaves, infrared light, visible light, ultraviolet light, X-rays, and gamma rays.

The electromagnetic spectrum is divided into different bands based on the frequency of the radiation. The different bands of the electromagnetic spectrum have different properties and are used for different purposes.

For example, radio waves are used for Communication, microwaves are used for cooking, infrared light is used for night vision, visible light is used for vision, ultraviolet light is used for tanning, X-rays are used for medical imaging, and gamma rays are used for cancer treatment.

Remote sensing systems consist of three main components: a sensor, a platform, and a data processing system.

The sensor is the part of the system that collects the data. The platform is the part of the system that carries the sensor. The data processing system is the part of the system that converts the data into a form that can be used by humans.

There are many different types of sensors that can be used for remote sensing. Some common types of sensors include cameras, radars, and lidars.

There are also many different types of platforms that can be used for remote sensing. Some common types of platforms include satellites, airplanes, and helicopters.

The data processing system is responsible for converting the data collected by the sensor into a form that can be used by humans. The data processing system may also be responsible for correcting the data for errors and for making the data more useful.

Remote sensing has many applications in a variety of fields, including:

agriculture: Remote sensing can be used to monitor crops, to assess crop yields, and to detect pests and diseases.
Forestry: Remote sensing can be used to monitor forests, to assess forest Health, and to detect illegal logging.
Water Resources: Remote sensing can be used to monitor Water Resources, to assess water quality, and to detect floods and droughts.
Environmental monitoring: Remote sensing can be used to monitor air quality, to track pollution, and to detect changes in land use.
Disaster Management: Remote sensing can be used to assess the damage caused by disasters, to monitor the progress of relief efforts, and to plan for future disasters.
Climate Change: Remote sensing can be used to monitor climate change, to track the melting of Glaciers, and to assess the Impact Of Climate Change on Ecosystems.
Security: Remote sensing can be used to monitor borders, to track illegal activities, and to detect terrorist threats.

Remote sensing is a powerful tool that can be used to collect data about a wide range of things. It is used in a variety of fields, including agriculture, forestry, water resources, environmental monitoring, disaster management, climate change, and security.

Here are some examples of how remote sensing is used in different fields:

In agriculture, remote sensing is used to monitor crops, to assess crop yields, and to detect pests and diseases. For example, remote sensing can be used to detect areas of crop Stress, which can be caused by drought, pests, or diseases. This information can be used to target Irrigation or pest control measures, which can help to improve crop yields.
In forestry, remote sensing is used to monitor forests, to assess forest health, and to detect illegal logging. For example, remote sensing can be used to map the extent of deforestation, which can be caused by logging, wildfires, or development.

Remote sensing is the acquisition of information about an object or phenomenon, without making physical contact with the object. In other words, it is the process of obtaining information about an object or area from a distance. Remote sensing is used in a wide variety of fields, including astronomy, meteorology, geology, Oceanography, and archaeology.

Principles of remote sensing

Remote sensing is based on the principle that electromagnetic radiation is emitted, reflected, or scattered by objects. The amount of radiation that is emitted, reflected, or scattered depends on the properties of the object, such as its temperature, composition, and texture. Remote sensing instruments can measure the amount of radiation that is emitted, reflected, or scattered by an object, and this information can be used to create images or maps of the object.

Electromagnetic spectrum

The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The electromagnetic spectrum includes radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays. The different types of electromagnetic radiation have different wavelengths and energies.

Components of remote sensing systems

A remote sensing system consists of three main components: a sensor, a platform, and a data processing system. The sensor is the instrument that measures the amount of electromagnetic radiation that is emitted, reflected, or scattered by an object. The platform is the vehicle that carries the sensor. The data processing system is used to convert the data from the sensor into images or maps.

Applications of remote sensing

Remote sensing is used in a wide variety of fields, including astronomy, meteorology, geology, oceanography, and archaeology. Some of the common applications of remote sensing include:

Mapping Remote sensing can be used to create maps of the Earth’s surface. These maps can be used for a variety of purposes, such as planning, navigation, and environmental monitoring.
Monitoring Remote sensing can be used to monitor changes in the Environment, such as changes in land use, deforestation, and pollution.
Resource management Remote sensing can be used to manage Natural Resources, such as forests, water resources, and Fisheries-2/”>Fisheries.
Disaster management Remote sensing can be used to monitor and respond to natural disasters, such as floods, earthquakes, and hurricanes.
Agriculture Remote sensing can be used to monitor crops, irrigation, and Soil conditions.
Forensics Remote sensing can be used to investigate crime scenes and to locate missing persons.
Archaeology Remote sensing can be used to locate and study archaeological sites.

Frequently asked questions

What is remote sensing?

What are the principles of remote sensing?

What is the electromagnetic spectrum?

The electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The electromagnetic spectrum includes radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays. The different types of electromagnetic radiation have different wavelengths and energies.

What are the components of a remote sensing system?

What are some of the applications of remote sensing?

Remote sensing is used in a wide variety of fields, including astronomy, meteorology, geology, oceanography, and archaeology. Some of the common applications of remote sensing include mapping, monitoring, resource management, disaster management, agriculture, forensics, and archaeology.

Question 1

Which of the following is not a component of a remote sensing system?

(A) Sensor
(B) Platform
(C) Data processor
(D) Data analyst

Answer
(D) Data analyst is not a component of a remote sensing system. The other three Options are all components of a remote sensing system.

Question 2

Which of the following is not a type of remote sensing platform?

(A) Aircraft
(B) Satellite
(C) Balloon
(D) Ground station

Answer
(D) Ground station is not a type of remote sensing platform. The other three options are all types of remote sensing platforms.

Question 3

Which of the following is not a type of remote sensing sensor?

(A) Optical sensor
(B) Radar sensor
(C) LiDAR sensor
(D) Thermal sensor

Answer
(A) Optical sensor is not a type of remote sensing sensor. The other three options are all types of remote sensing sensors.

Question 4

Which of the following is not a use of remote sensing?

(A) Land use mapping
(B) Crop monitoring
(C) Disaster management
(D) Data analysis

Answer
(D) Data analysis is not a use of remote sensing. The other three options are all uses of remote sensing.

Question 5

Which of the following is not a benefit of remote sensing?

(A) It can be used to collect data over large areas.
(B) It can be used to collect data in difficult-to-access areas.
(C) It can be used to collect data in real time.
(D) It is a very expensive technology.

Answer
(D) Remote sensing is not a very expensive technology. The other three options are all benefits of remote sensing.