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Basic of Remote Sensing II

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Remote Sensing Process

A. Energy Source or Illumination – the first requirement is to have an energy source which illuminates or provides electromagnetic energy to the target of interest.
B. Radiation and the Atmosphere – as the energy travels from its source to the target, it will come in contact with and interact with the atmosphere it passes through. This interaction may take place a second time as the energy travels from the target to the sensor.
C. Interaction with the Target – once the energy makes its way to the target through the atmosphere, it interacts with the target depending on the properties of both the target and the radiation.
D. Recording of Energy by the Sensor – after the energy has been scattered by, or emitted from the target, we require a sensor to collect and record the EMR.
E. Transmission, Reception, Processing – the energy recorded by the sensor has to be transmitted, often in electronic form, to receiving and processing station where the data are processed into an image.
F. Interpretation and Analysis – the processed image is interpreted, visually and/or digitally or electronically, to extract information about the target which was illuminated.
G. Application – the final element of the remote sensing process is achieved when we apply the information we have been able to extract from the imagery about the target in order to better understand it, reveal some new information, or assist in solving a particular problem.

 Remote Sensing Principle
Electromagnetic energy reaching the Earth’s surface from the Sun is reflected, transmitted or absorbed.
Specific targets/ objects have individual and characteristic manner of interacting with incident radiation that is described by the spectral response of that target.
Eg. – soils of different types, water with varying degrees of impurities or vegetation of various species.
EMR like radio waves, IR waves make characteristic patterns as they travel through space. Each wave has a certain shape and length. The distance between peaks is called wavelength.
The light which our eyes (our remote sensors) – can detect is part of the VISIBLE SPECTRUM. The visible wavelengths cover a range from approximately 0.4 to 0.7 µm; (1 µm = 1*10-6 of a meter).

Wavelength, Frequency, Amplitude
The EMS ranges from the shorter wavelengths (including gamma & X-rays) to the longer wavelengths (including MWs & RWs).
There are several regions of the EMS which are useful for Remote Sensing.
Electro Magnetic Spectrum

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