EVALUATION OF NEW COMMERCIAL HYPERSPECTRAL SENSORS FOR MAPPING MINERAL ALTERATION IN VIRGINIA CITY, NEVADA

The University of Nevada, Reno has been evaluating the geological applications of hyperspectral sensors for mapping mineralized areas in Virginia City for almost 20 years. This paper compares three commercial hyperspectral sensors (Probe-1, HyMap and HyperSpecTIR) against low- and high-altitude hyperspectral data from the NASA AVIRIS system.

Probe-1 and HyMap are similar hyperspectral reflectance sensors and were manufactured by the same Australian firm. They utilize a whiskbroom style scanning mechanism to collect data in a cross-track direction while the aircraft moves down track. Reflected solar radiation dispersed by four spectrometers onto four different linear arrays. The sensors have 128 bandpasses that vary in width from 16 nanometers to 12 nanometers. Ground spatial resolutions between 3 meters to 10 meters are possible. Probe-1 data were acquired in 1998 as a part of the Geosat Committee Group Shoot and HyMap data were acquired in 1999. High-Altitude AVIRIS data were acquired in 1995 and low-altitude AVIRIS data were acquired on October 10, 1998.

HyperSpecTIR is manufactured by SpecTIR Corporation of Santa Barbara, California. It uses an area array where the spectral dimension is across track while the spatial dimension is along track. The sensor uses an INS/GPS to freeze the motion of a 256 by 256 element array in the down track dimension while it scans spectra in the cross track dimension. The sensor has 256 spectral bands ranging in width from 4 nanometers to 10 nanometers. Ground spatial resolutions can range from 1 meter to 10 meters and signal to noise from 350:1 to 1100:1 is achievable with selectable dwell times. HyperSpecTIR data were acquired over Virginia City on June 29, 2001 at 1530 hours. This paper compares the relative utility of data from these sensors for identification and mapping of mineral alteration in Virginia City, Nevada.