Remote Sensing

Remote sensing is a technology to gather information and analyzing an object or phenomenon without making any direct contact

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Remote sensing satellites are satellites equipped with sensors that observe the earth and collect remote sensing data

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Optical and Infrared Remote Sensing uses satellites with optical sensors to detect solar radiation reflected or scattered from the earth and thus develop images of Earth

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Why do we use remote sensing?

• Automated
• Useful for extreme conditions
• Offers excellent spatial and temporal coverage
• Provides real-time or near-real-time observations
• Often cost-effective
• Extends our senses
• Monitor changes to an environment over time

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Remote sensing interpretation and analysis techniques:

• Visual interpretation
• Radiation (reflectance) analysis
  • Each pixel has a numeric value representing the amount of energy reflected in specific wavelengths – which can be used to characterize the condition of the object

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The principles of remote sensing is illustrated in the diagram below:

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Electromagnetic Spectrum & Wavelengths in Remote Sensing

Firstly, below is the electromagenetic spectrum:

Application in GIS

Any remotely sensed parameter, which directly or indirectly characterizes the nature and/or condition of the object under observation, is defined as its signature.

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The spectral signatures of an object is defined as the unique pattern of wavelengths radiated by an object

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Spectral reflectance characteristics of a healthy green vegetation:

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