Hyperspectral imaging of minerals in the longwave infrared: The use of laboratory directional-hemispherical reference measurements for field exploration data

Tanya L. Myers, Timothy J. Johnson, Neal B. Gallagher, Bruce E. Bernacki, Toya N. Beiswenger, James E. Szecsody, Russell G. Tonkyn, Ashley M. Bradley, Yin Fong Su, Tyler O. Danby

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

Hyperspectral imaging (HSI) continues to grow as a method for remote detection of vegetation, materials, minerals, and pure chemicals. We have used a longwave infrared (7.7 to 11.8 μm) imaging spectrometer in a static outdoor experiment to collect HSI data from 24 minerals and background materials to determine the efficacy with which HSI can remotely detect and distinguish both pure minerals and mineral mixtures at a 45-deg tilt angle relative to ground using two different backgrounds. Measurements were obtained separately for the minerals and materials mounted directly on both a bare plywood board and a board coated with aluminum foil: 19 powders (3 mixtures and 16 pure mineral powders) held in polyethylene bottle lids as well as five samples in rock form were taped directly to the boards. The primary goal of the experiment was to demonstrate that a longwave infrared library of solids and minerals collected as directional-hemispherical reflectance spectra in the laboratory could be used directly for HSI field identification along with simple algorithms for a rapid survey of the target materials. Prior to the experiment, all 24 mineral/inorganic samples were measured in the laboratory using a Fourier transform infrared spectrometer equipped with a gold-coated integrating sphere; the spectra were assimilated as part of a larger reference library of 21 pure minerals, 3 mixtures, and the polyethylene lid. Principal component analysis with mean-centering was used in an exploratory analysis of the HSI images and showed that, for the aluminum-coated board, the first principal component captured the difference between the signal that resembled a blackbody and the highly reflective aluminum background. In contrast, the second, third, and fourth principal components were able to discriminate the materials including phosphates, silicates, carbonates, and the mixtures. Results from generalized least squares target detection clearly showed that laboratory reference spectra of minerals could be utilized as targets with high fidelity for field detection.

Original languageEnglish
Article number034527
JournalJournal of Applied Remote Sensing
Volume13
Issue number3
DOIs
StatePublished - Jul 1 2019
Externally publishedYes

Funding

This work was partly supported by the U.S. Department of Energy, National Nuclear Security Administration, Office of Defense Nuclear Nonproliferation (DNN, NA-22). We thank our sponsor for their support. The Pacific Northwest National Laboratory is operated for the United States Department of Energy by the Battelle Memorial Institute under contract DE-AC05-76RLO 1830. The authors declare that there is no conflict of interest. This work was partly supported by the U.S. Department of Energy, National Nuclear Security Administration, Office of Defense Nuclear Nonproliferation (DNN, NA-22).We thank our sponsor for their support. The Pacific Northwest National Laboratory is operated for the United States Department of Energy by the Battelle Memorial Institute under contract DE-AC05-76RLO 1830. The authors declare that there is no conflict of interest.

FundersFunder number
United States Department of Energy
U.S. Department of Energy
BattelleDE-AC05-76RLO 1830
National Nuclear Security Administration
Office of Defense Nuclear NonproliferationNA-22

    Keywords

    • directional hemispherical reflectance
    • hyperspectral imaging
    • infrared
    • longwave infrared
    • minerals
    • particle size
    • principal component analysis

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