Hyperspectral

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Hyperspectral scanners look at objects using a vast portion of the light spectrum, most notably in the visible and infrared areas of the spectrum. Hyperspectral imaging collects the same picture on many bands of the light spectrum to generate a “datacube” that can reveal objects and information that more limited scanners cannot pick up. Another advance of this form of imaging is that different elements leave unique spectral signatures behind in various bands of the spectrum. Using these specific signatures, it is possible to identify the materials that make up a scanned object. The accuracy of these scanners is typically measured in spectral resolution, which is the width of each band of the spectrum that is captured. If the scanner picks up on a large number of fairly small wavelengths, it is possible to identify objects even if said objects are only captured in a handful of pixels. However, spatial resolution is a factor in addition to spectral resolution. If the pixels are too large, then multiple objects are captured in the same pixel and become difficult to identify. If the pixels are too small, then the signal-to-noise ratio is too high and again, analysis becomes difficult. These images are usually generated from airborne scanners like the NASA’s Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) or from satellites like NASA’s Hyperion. (Schurmer, 2003). However, handheld scanners are also in use (Ellis, 2001). One of the unique aspects of this form of imaging is the massive amount of data that it generates. Because every image is taken 200 times over, the result of any given scan contains millions of pixels. One of the hurdles that researchers have had to face has been finding ways to program hyperspectral satellites to sort through data on their own and transmit only the most important images, as both transmission and storage of that much data could prove difficult and costly (Schurmer, 2003).

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[edit] Hyperspectral Surveillance

Hyperspectral surveillance is the implementation of hyperspectral scanning technology for surveillance purposes. Hyperspectral imaging is particularly useful in military surveillance because of measures that military entities now take to avoid airborne surveillance. Airborne surveillance has been in effect since soldiers used tethered balloons to spy on troops during the Civil War, and since that time we have learned not only to hide from the naked eye, but to mask our heat signature to blend in to the surroundings and avoid infrared scanning, as well. The idea that drives hyperspectral surveillance is that hyperspectral scanning draws information from such a large portion of the light spectrum that any given object should have unique spectral signature in at least a few of the many bands that get scanned (Schurmer, 2003).

[edit] Other applications

Hyperspectral technology is by no means limited to military applications. This technology is continually becoming ever more available to the public, and has been used in a wide variety of ways. Hyperspectral imaging is even powerful enough to identify plant matter, and can be used to help locate unhealthy plant matter. Not only has the technology become widely available, but the information has spread, too. Organizations such as NASA and the USGS have catalogues of various minerals and their spectral signatures, and have posted them online to make them readily available for researchers. The ability of hyperspectral imaging to identify various minerals makes it ideal for the mining and oil industries, where it can be used to look for ore and oil (Ellis 2001, Smith 2006).


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