Hyperspectral Surface Materials Maps

Using a National Aeronautics and Space Administration (NASA) WB-57 aircraft flown at an altitude of approximately 15,240 meters (roughly 50,000 feet), 218 flight lines of hyperspectral data were collected over Afghanistan between August 22 and October 2, 2007. These HyMap data were processed, empirically adjusted using ground-based reflectance measurements, and georeferenced to Landsat base imagery. Each pixel of processed HyMap data was compared to reference spectrum entries in a spectral library of minerals, vegetation, water, ice, and snow in order to characterize surface materials across the Afghan landscape. For details on HyMap data acquisition, see http://pubs.usgs.gov/of/2008/1235/; for processing protocols, see http://pubs.er.usgs.gov/publication/ofr20111155  and http://pubs.er.usgs.gov/publication/70036150.

Using the HyMap data, two surface materials maps of Afghanistan were produced: one that shows carbonates, phyllosilicates, sulfates, altered minerals, and other materials spatial distribution of minerals with diagnostic absorption features in the shortwave infrared wavelengths and another that depicts iron-bearing minerals and other materials having diagnostic absorption features at visible and near-infrared wavelengths. The 31 classes in the list of materials comprising each map key represent a necessary compromise between striving for the highly focused level of detail achievable in the best calibrated flight lines and seeking identifications that were reliably detected across the entire country and present in large enough areas to be perceptible at the scale of a national map.

Surface Materials Map of Afghanistan: Carbonates, Phyllosilicates, Sulfates, Altered Minerals, and Other Materials	Surface Materials Map of Afghanistan: Iron-bearing Minerals and Other Materials