Calibration of the Afghanistan Hymap Dataset

The use of hyperspectral remote sensing data as a materials mapping tool continues to gain acceptance and application. As the number of spectral libraries and our understanding of spectral properties of materials expands, so does the opportunity to apply remotely sensed data to geologic investigations. To ensure the utility of a hyperspectral dataset, a rigorous calibration process to remove atmospheric absorptions and residual instrument artifacts must be applied. Proper calibration of hyperspectral data is essential to produce accurate surficial material maps. Traditionally, several techniques have been used to calibrate data and remove atmospheric effects [1]. A detailed modified method used to calibrate the 2007 Afghanistan HyMap dataset [2] is described here. Because of the extreme topographic relief and restricted access to ground calibration sites, modifications to the traditional USGS calibration procedures [1] were required. To meet the challenges of the Afghanistan hyperspectral dataset, we developed a calibration process using elevation-based ACORN (Atmospheric CORrection Now) [3] corrections, ground calibration sites, and atmospherically corrected cross-cutting calibration flight lines to maximize the utility and accuracy of the country-wide data.