Remote Sensing: Types, Applications, And Remote Sensing Satellites

Remote sensing is a technique used for detecting and monitoring the physical characteristics of an object or phenomenon without making physical contact with the object.

• Remote sensing is generally used in satellites or aircraft to detect the surface, atmosphere, and oceans on Earth.
• This technique is also used in many fields like geography, geophysics, land surveying, oceanography, meteorology, glaciology, military, intelligence, etc.
• Remote sensing techniques are of two types: Active remote sensing and Passive remote sensing.
• In Active remote sensing, signals in the form of electromagnetic waves are emitted by a satellite or aircraft to the object, and its reflection is detected by the sensor of the satellite or aircraft.
• In Passive remote sensing, sunlight reflected from the object is detected by the sensor of the satellite or aircraft.

Key Terms: Remote Sensing, Active and Passive Sensors, Satellites, Electromagnetic Waves, LIDAR, GPS, GIS, Radar

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Remote Sensing

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Remote sensing is a technique used to gather information about an object or phenomenon without making any physical contact with the object. Generally, this technique is used in satellites or aircraft to detect the surface, atmosphere, and oceans on Earth.

• Electromagnetic signals coming from the object are detected by the sensor used in satellites or aircraft to gather information about it. 
• It converts the energy emitted from the object into voltage form or digital form so that the sensor can give the actual color, shape, size, and height of the object.
• With the help of remote sensing technology, human beings can know more about any object like a forest, mountains, rivers, rural areas, urban areas, coastal areas, seas, oceans, etc.
• The remote Sensing technique made it possible to observe the objects of the earth and measure and analyze them without any physical interaction.
• A geographic information system (GIS) is a computer tool that manages, analyzes, stores, and visualizes geographic data.
• GIS data acquisition used several methods for gathering data into a GIS database e.g., remote sensing, the global positioning system (GPS), etc.

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Types of Remote Sensing

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There are two types of remote sensing methods are used:

1. Active remote sensing 
2. Passive remote sensing.

Active Remote Sensing

In the active remote sensing method, energy in the form of electromagnetic waves is emitted from the active sensors of a satellite or aircraft to the object, and then the reflected signal from the object is detected and measured.

• LiDAR and RADAR are examples of active remote sensing.
• In active remote sensing the time delay between emitted and reflected signal is measured to detect the speed, location, and direction of an object.

Passive Remote Sensing

In the Passive sensing method, radiation is gathered by the passive sensors that are emitted or reflected by the object or surrounding areas.

• The most common source of radiation measured by passive sensors is reflected sunlight.
• Examples of passive remote sensors are infrared, film photography, radiometers, and charge-coupled devices.

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Remote Sensing Applications

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Following are the applications that use remote sensing techniques:

• The remote sensing technique used in Doppler radar is used for monitoring speed limits by local law enforcement and in the meteorological collection such as wind speed.
• Laser and radar altimeters on satellites measure the wavelength and height of ocean waves, the direction and speed of the wind, and surface ocean currents and directions.
• Sea level, tides, and wave direction are measured by ultrasound (acoustic) and radar tide gauges in coastal and offshore locations.
• The light detection and ranging (LIDAR) technique is used for measuring the concentration of various chemicals in the atmosphere. The main application of LIDAR is Vegetation remote sensing.
• For a wide range of frequencies, radiometers and photometers are used to collect the reflected radiation and the radiation that is emitted. The most common are visible and infrared sensors, followed by gamma-ray, microwave, and ultraviolet. 

Remote Sensing Process
 

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What are Remote Sensing Satellites?

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Remote Sensing Satellites is a machine to detect an object from a distance and then monitors its features by analyzing the emitted energy or electromagnetic waves from the object.

• It interprets an object or machine which orbits an object or planet etc. to take its imagery and analyze the features of the objects.
• Remote Sensors and cameras are fitted in these satellites to take images when the object reflects radiation or electromagnetic waves.

Remote Sensing Satellite

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What are Electromagnetic Waves?

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Electromagnetic Waves are waves that are produced because of the vibrations created by a magnetic field and an electric field.

• When an object reflects radiation or energy, it comes through electromagnetic waves in space, and then the remote sensors receive the images of the object.
• Radiation or energy that comes from an object helps the detectors to take images of that object and analyze it based on its features.
• The radiation or energies are emitted by various stars that are present in space.

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Things to Remember  

• Remote sensing technologies are an invention of human beings on the earth to detect, observe and interpret an object by analyzing the object by taking its imagery.
• The imagery can be taken with the help of reflected energy from the object or other stars.
• Remote sensors are used to gather information about various objects that are in space or the Earth’s surface. It collects information about the ocean, forest, land, agriculture, mountains, hills, roads, etc., and the size, and shape of those data.
• GIS is a computer tool that manages, analyzes, stores, and visualizes geographic data.
• The LIDAR technique is used for measuring the concentration of various chemicals in the atmosphere.