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Passive Sensors
Optical Remote Sensing
The Center for Space Research is currently involved in several aspects of optical remotely sensed imagery including feature extraction and classification of multispectral and hyperspectral imagery.
Illustration of solar energy
interaction with the Earth's surface |
Passive Sensors are the most common sensors onboard Earth observing satellites such as Landsat or SPOT and meteorological satellites such as GOES. Passive sensors use the sun as their illumination source and measure the amount of reflected energy from the sun off of the Earth's surface. Energy falling upon the surface is either absorbed, reflected, or transmitted through the surface. Studying the reflectance, transmittance, and absorbtion of a surface reveals information about the nature of the surface and the atmosphere. These sensors are commonly known as radiometers and spectrometers.
Radiometers and spectrometers collect data in several different wavelengths of the Electromagnetic (EM) Spectrum - typically the visible and near infrared and sometimes the thermal infrared. This type of data (commonly referred to as multispectral data) is beneficial because different types of features on Earth will have different responses at different wavelengths. For instance, vegetation may reflect only a small amount of energy (5%-10%) in a visible band (0.45 microns), but will reflect a large amount of energy (45%-50%) in an infrared band (0.8 microns).
The following sections provide some general information about optical imagery as well as applications that CSR/RS is involved with.
Sensors
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