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Basic of Remote Sensing IV

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Sources of Electromagnetic Energy There are three main sources of  electromagnetic radiation that are used in  remote sensing:  Solar radiation (natural radiation from the  sun)  Terrestrial radiation (natural radiation  emitted by Earth's surface)  Artificial radiation (from a remote sensing  system) Solar Radiation The Sun yields a continuous spectrum of EM  energy. This Incident radiation can be reflected  from the Earth's surface. This process produces a large amount of  short wavelength energy (from 0.4 - 0.7 µm;  blue, green, and red light). It can also be emitted by the Earth's  surface. Such emitted radiation is typically  of a longer wavelength, in the middle and  far infra-red wavelengths. Interacts with the atmosphere and surface  materials (reflect, absorb).  Since the Sun has a much higher temperature  (6000 degrees K) than the Earth (303 degrees  K), so t...
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Basic of Remote Sensing

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Contents What is Remote Sensing? Need for Remote Sensing? Who uses Remote Sensing and Why? Remote Sensing :  The art & science of  acquiring, processing, and interpreting information (images and related data) about the Earth’s surface without  actually being in physical contact between the object and sensor. This is done by sensing & recording reflected or emitted energy  and processing, analyzing and applying that information. The images and related data are obtained from ground-based, air-or space- borne instruments that record the interaction between matter (target) and  electromagnetic radiation. " remotely" means using instruments (sensors) carried by platforms . Need For Remote Sensing Systematic data collection; Global coverage; Repeatability; Inaccessible areas – sometimes the only solution; Multi-purpose information Who Uses Remote Sensing & Why The geographer who looks for changes in the E...
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Electromagnetic Spectrum

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Electromagnetic Spectrum EMR is a form of energy exhibiting wave-like behaviour as it travels through space. EMR ranges from very high energy radiation such as gamma rays and X rays through ultraviolet light, visible light, infrared radiation and microwaves to radio waves.  The range of frequencies of EMR is known as the electromagnetic spectrum. The Sun produces a continuous spectrum of energy from gamma rays to radio waves that continually bathe the Earth in energy. The visible portion of the spectrum may be measured using wavelength (measured in mm or nm) or electron volts (eV) - All units are interchangeable. Classification of Electromagnetic Radiation Infrared radiation (750 nm - 1 mm) The infrared region can be divided into two categories based on their radiation properties - the reflected IR, and the emitted or thermal IR. The reflected IR covers wavelengths from approximately 0.7 micrometres to 3.0 micrometres. The thermal IR covers wavelengths from appro...
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