Analysis of multispectral and hyperspectral longwave infrared (LWIR) data for geologic mapping

Abstract

Multispectral MODIS/ASTER Airborne Simulator (MASTER) data and Hyperspectral Thermal Emission Spectrometer (HyTES) data covering the 8 -12 m spectral range (longwave infrared or LWIR) were analyzed for an area near Mountain Pass, California. Decorrelation stretched images were initially used to highlight spectral differences between geologic materials. Both datasets were atmospherically corrected using the ISAC method, and the Normalized Emissivity approach was used to separate temperature and emissivity. The MASTER data had 10 LWIR spectral bands and approximately 35-meter spatial resolution and covered a larger area than the HyTES data, which were collected with 256 narrow (approximately 17nm-wide) spectral bands at approximately 2.3-meter spatial resolution. Spectra for key spatially-coherent, spectrally-determined geologic units for overlap areas were overlain and visually compared to determine similarities and differences. Endmember spectra were extracted from both datasets using n-dimensional scatterplotting and compared to emissivity spectral libraries for identification. Endmember distributions and abundances were then mapped using Mixture-Tuned Matched Filtering (MTMF), a partial unmixing approach. Multispectral results demonstrate separation of silica-rich vs non-silicate materials, with distinct mapping of carbonate areas and general correspondence to the regional geology. Hyperspectral results illustrate refined mapping of silicates with distinction between similar units based on the position, character, and shape of high resolution emission minima near 9 m. Calcite and dolomite were separated, identified, and mapped using HyTES based on a shift of the main carbonate emissivity minimum from approximately 11.3 to 11.2 m respectively. Both datasets demonstrate the utility of LWIR spectral remote sensing for geologic mapping.

Cryogenic Refocusing of an Ultrawide FOV Long-Wave Infrared Imaging Spectrometer in a Geostationary Orbit

“…When combined with visible to near-infrared, short-wave infrared, and mid-wave infrared imaging spectrometers, it can accomplish continuous monitoring over a wide range throughout the day, satisfying the demands of space remote sensing applications for high-accuracy target classification and identification. Additionally, it has been extensively used in mineral exploration and geological mapping [16], gas detection and recognition [17], environmental monitoring and resource investigation [18], military reconnaissance and security defense [19], etc. Table 1 displays some of the main specifications of the LWIR imaging spectrometer.…”

Automated lithological mapping using airborne hyperspectral thermal infrared data: A case study from Anchorage Island, Antarctica

“…Previous studies using airborne hyperspectral TIR data have illustrated the exceptional potential of these types of sensors for mapping silicates, carbonates, sulphates, and clays (e.g. Hewson et al, 2000;Cudahy et al, 2001;Calvin et al, 2001;Vaughan et al, 2003Vaughan et al, , 2005Aslett et al, 2008;Riley and Hecker, 2013;Kruse and McDowell, 2015).…”