Remote Sensing

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

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

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

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

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

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

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.

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

Spectral reflectance characteristics of a healthy green vegetation: