The term 'remote sensing' was first used in the United States office of Naval Research. The concept of Satellite remote sensing however dates as far back as the early days of space age when both Russians and Americans began a dual approach towards imaging surfaces using several types of sensors from spacecraft. Today Remote Sensing has far progressed from its initial conceptions. This cutting edge technology encompasses a wide array of elements and is extensively used in almost all areas of industry and science.
What is Remote Sensing?
Remote sensing is the observation of an object, surface or phenomenon from a distance without actually being in contact with it. It is based on the principle that objects reflect or emit radiations in different wavelengths and intensities depending on specific conditions. An aircraft, spacecraft, satellite or ship may be used for this purpose equipped with recording devises such as camera, laser, radar, sonar, seismograph, gravimeter, etc. These devices are sensitive to electromagnetic energy such as light, heat and radio waves (from the target object) and help to analysis the electromagnetic spectrum by studying energy interactions and providing information in the form of digital mapping (using imaging systems). With advancements in information technology remote sensing is prominently being carried out using digital processes, however non-digital methods can also be employed depending on specific needs.
Remote Sensing typically comprises of following elements:
- Electro-magnetic energy
- Target (s) that is to be studied
- Spectral response (of the specific target objects under conditions of study)
Remote Sensing process is carried out in the following stages:
- Data Acquisition
- Data Processing and analyzing (typically involves image enhancement, geo-coding, filtering, band transforms, etc)
- Date Fusion
- Data Interpretation
- Data Utilization (may involve input of data in to GIS)
How is Remote Sensing Useful?
Data collection using Remote Sensing offers a variety of advantages compared to other forms of data acquisition. Remote Sensing makes it possible to measure energy (such as ultra-violet, infrared, microwave, etc) at wavelengths that cannot be reached by human vision. Scientific advancements have resulted in use of Remote Sensing in a variety of discipline such as agriculture, forestry, hydrology, geology, cartography, meteorology, etc.
One important application of Remote Sensing is in the field of oceanography. Here Remote Sensing may be used to acquire following information:
- Details about ocean pigmentation
- Particulars pertaining to location, direction and speed of currents
- Determine sea surface temperature
- Locate direction and speed of wind
- Determine location, direction and speed of waves, etc
Although remote sensing is useful in an array of areas, its usage is most significant in the context of terrestrial observations. Global monitoring is possible from any site of earth using Remote Sensing.
Fundamentals of Satellite Remote Sensing
Satellite Remote Sensing involves gathering information about the earth's surface using satellites orbiting around the earth. Satellite remote sensing may be done two ways:
- Using passive sensor systems - Contains an array of small detectors or sensors that can detect electro-magnetic radiations emitted from the earth's surface
- Using active sensor systems - The system sends out electro magnetic radiation towards target object (s) and measures the intensity of the return signal.
Data collected by the satellites are then transmitted to ground stations wherein images of earth's surface are reconstituted to obtain the required information.
Advantages of Satellite Remote Sensing
Take a look at few benefits of Satellite remote sensing:
- Enables continuous acquisition of data
- Helps to receive up-to-date information (satellite remote sensing can be programmed to enable regular revisit to object or area under study)
- Offers wide regional coverage and good spectral resolution
- Offers accurate data for information and analysis
- Serves as a large archive of historical data
Data collected using satellite remote sensing can be used for any of the following purposes
- Assessing and observing vegetation types
- Conducting soil surveys
- Carrying out mineral exploration
- Map making to facilitate easy study of information
- Construct thematic maps based on requirement
- Planning and monitoring water resources
- Carry out urban planning
- Assessing crop yields and other agriculture management
- Assessing and managing natural disaster, Etc
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