HySpex by NEO (HySpex) VNIR-1800 and SWIR-384 imaging spectrometer radiance data were acquired on September 14, 2017 at the Cresson Pit of the Cripple Creek & Victor mine in Cripple Creek, Colorado. ASD FieldSpecⓇ NG data were collected on September 13 and 14, 2017 at two calibration sites within the Cresson Pit imaged with the HySpex imaging spectrometers. The HySpex VNIR-1800 imaging spectrometer is a push broom type instrument that utilizes 1800 pixels to collect 186 channels of spectral data in the region of 400 to 1000 nanometers (nm). The spectral sampling interval of the HySpex VNIR-1800 is 3.26 nm with a 17° field of view (Norsk Elektro Optikk AS, 2016b). The HySpex SWIR-384 imagining spectrometer is a push broom type instrument that utilizes 384 pixels to collect 288 channels of spectral data in the region of 930 to 2500 nm. The spectral sampling interval of the HySpex SWIR-384 is 5.45 nm with a 16° field of view (Norsk Elektro Optikk AS, 2016a). The ASD FieldSpecⓇ NG point spectrometer has a spectral range of 350 to 2500 nm, a spectral resolution of 3 nm @ 700 nm and 6 nm @ 1400/2100 nm, with a spectral sampling of 1.4 nm @ 350 to 1000 nm and 1.1 nm @ 1001 to 2500 nm. The ASD FieldSpecⓇ NG collects 2151 channels of spectral data within a 25° field of view (Malvern Panalytical, 2018).
Imaging spectrometer data were collected by mounting the HySpex VNIR-1800 and SWIR-384 imaging spectrometers on a rotating stage at the southeast portion of the Cresson Pit. The distance from the imaging spectrometers to areas imaged on the opposite side of the pit ranged from approximately 300 to 1500 m. This resulted in a pixel size of 4.7 to 23.4 cm for the VNIR data and 22 to 110 cm for the SWIR data.
ASD FieldSpecⓇ NG spectra from each calibration site were spectrally averaged, converted to absolute reflectance, and convolved to the bandpass and sampling interval of the HySpex data. HySpex radiance spectra from regions of interest that encompassed the calibration sites were also spectrally averaged. Multipliers were generated by dividing the averaged and convolved ASD FieldSpecⓇ NG calibration site absolute reflectance data with the averaged HySpex radiance data encompassing the calibration sites. HySpex reflectance data cubes were generated by applying the multipliers to the HySpex radiance data cubes. The resultant reflectance cubes were then combined to create the reflectance mosaic. White mica wavelength position maps were generated using routines in the U.S. Geological Survey PRISM version1aq software suite (Kokaly, 2011).
References Cited:
Kokaly, R.F., 2011, PRISM: Processing routines in IDL for spectroscopic measurements (installation manual and user's guide, version 1.0): U.S. Geological Survey Open-File Report 2011-1155, 432 p., https://doi.org/10.3133/ofr20111155.
Malvern Panalytical, 2018, ASD FieldSpec 4 Hi-Res NG Spectroradiometer, accessed December 1, 2018 at https://www.malvernpanalytical.com/en/products/product-range/asd-range/fieldspec-range/fieldspec-4-hi-res-ng-spectroradiometer/.
Norsk Elektro Optikk AS, 2016a, HySpex SWIR-384, accessed June 1, 2017 at http://www.hyspex.no/products/.
Norsk Elektro Optikk AS, 2016b, HySpex VNIR-1800, accessed June 1, 2017 at http://www.hyspex.no/downloads/.
