In remote sensing, the electromagnetic imaging sensor is known as Synthetic Aperture Radar, or SAR, is often used. In order to get a clear picture of the Earth's surface, the SAR sensor is attached to an airplane or satellite. This technology is sometimes used in more distant applications, such as taking images of Venus's surface.
|
SAR Image/ SAR Sensors |
Optical Image/ Optical Sensors |
|
The image
captured from synthetic aperture radar is called SAR image. |
The Image
captured from optical sensor like a film camera or a TV camera is called
optical image. |
|
SAR uses a
wavelength of 1 cm to 1 m. |
Optical
sensors use wavelengths near that of visible light, or 1 micron. |
|
Optical
sensors cannot see through clouds or storms because of the difference in
wavelengths. Because electromagnetic waves scatter or reflect at various
frequencies and wavelengths, the Earth's surface appears substantially
different in the two sensors. The intensity of the received signal is
typically determined by the surface roughness of objects that seem smooth at
one wavelength but relatively rough at a shorter one. |
|
|
SAR sensor
carries its own illumination source, in the form of radio waves transmitted
by an antenna |
optical
sensors rely upon the sun's illumination or thermal radiation to create the
brightness that is observed by the sensor |
|
The picture captured
by an optical sensor change with the time of day due to variations in the
sun's angle, while SAR can be utilised effectively at any time of day or
night. |
|
|
SAR is a
side-looking sensor. |
Optical
sensors mainly look straight down. |
|
Both the
images contain different information, and for some applications SAR images
are better, while for other applications, optical images are better. For
example, SAR is better for imaging the ice in the Canadian Arctic. In an
optical image, snow and ice appear bright white, and relatively featureless.
But in a SAR image, the surface roughness patterns are clearly portrayed, and
trained observers can deduce the age and thickness of the ice. |
|
Satellite data may be used in a variety of ways, each with advantages and disadvantages. radar imaging is better than optical imagery when it's foggy and you're looking to emphasize the roughness of the surfaces.
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Note: If you are taking help from the above work and also incorporating the above content in your research work, Kindly make sure you are citing the below papers.
- https://www.sciencedirect.com/science/article/pii/S2215098617314003
- https://www.sciencedirect.com/science/article/pii/S1319157817301106
- https://www.sciencedirect.com/science/article/pii/S1319157817303865
- https://link.springer.com/article/10.1007/s11831-021-09548-z
Reviewed by IPR
on
February 24, 2022
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