Field-Based High-Quality Emissivity Spectra Measurement Using a Fourier Transform Thermal Infrared Hyperspectral Imager

Emissivity information derived from thermal infrared (TIR) hyperspectral imagery has the advantages of both high spatial and spectral resolutions, which facilitate the detection and identification of the subtle spectral features of ground targets. Despite the emergence of several different TIR hyper...

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Autores principales:	Lyuzhou Gao, Liqin Cao, Yanfei Zhong, Zhaoyang Jia
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	hyperspectral thermal infrared field-based measurement temperature and emissivity retrieval spatial convolution denoising Hyper-Cam LW imager Science Q
Acceso en línea:	https://doaj.org/article/a0bf07ca9b9a4d3d85a456655c22026c
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spelling	oai:doaj.org-article:a0bf07ca9b9a4d3d85a456655c22026c2021-11-11T18:57:30ZField-Based High-Quality Emissivity Spectra Measurement Using a Fourier Transform Thermal Infrared Hyperspectral Imager10.3390/rs132144532072-4292https://doaj.org/article/a0bf07ca9b9a4d3d85a456655c22026c2021-11-01T00:00:00Zhttps://www.mdpi.com/2072-4292/13/21/4453https://doaj.org/toc/2072-4292Emissivity information derived from thermal infrared (TIR) hyperspectral imagery has the advantages of both high spatial and spectral resolutions, which facilitate the detection and identification of the subtle spectral features of ground targets. Despite the emergence of several different TIR hyperspectral imagers, there are still no universal spectral emissivity measurement standards for TIR hyperspectral imagers in the field. In this paper, we address the problems encountered when measuring emissivity spectra in the field and propose a practical data acquisition and processing framework for a Fourier transform (FT) TIR hyperspectral imager—the Hyper-Cam LW—to obtain high-quality emissivity spectra in the field. This framework consists of three main parts. (1) The performance of the Hyper-Cam LW sensor was evaluated in terms of the radiometric calibration and measurement noise, and a data acquisition procedure was carried out to obtain the useful TIR hyperspectral imagery in the field. (2) The data quality of the original TIR hyperspectral imagery was improved through preprocessing operations, including band selection, denoising, and background radiance correction. A spatial denoising method was also introduced to preserve the atmospheric radiance features in the spectra. (3) Three representative temperature-emissivity separation (TES) algorithms were evaluated and compared based on the Hyper-Cam LW TIR hyperspectral imagery, and the optimal TES algorithm was adopted to determine the final spectral emissivity. These algorithms are the iterative spectrally smooth temperature and emissivity separation (ISSTES) algorithm, the improved Advanced Spaceborne Thermal Emission and Reflection Radiometer temperature and emissivity separation (ASTER-TES) algorithm, and the Fast Line-of-sight Atmospheric Analysis of Hypercubes-IR (FLAASH-IR) algorithm. The emissivity results from these different methods were compared to the reference spectra measured by a Model 102F spectrometer. The experimental results indicated that the retrieved emissivity spectra from the ISSTES algorithm were more accurate than the spectra retrieved by the other methods on the same Hyper-Cam LW field data and had close consistency with the reference spectra obtained from the Model 102F spectrometer. The root-mean-square error (RMSE) between the retrieved emissivity and the standard spectra was 0.0086, and the spectral angle error was 0.0093.Lyuzhou GaoLiqin CaoYanfei ZhongZhaoyang JiaMDPI AGarticlehyperspectralthermal infraredfield-based measurementtemperature and emissivity retrievalspatial convolution denoisingHyper-Cam LW imagerScienceQENRemote Sensing, Vol 13, Iss 4453, p 4453 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	hyperspectral thermal infrared field-based measurement temperature and emissivity retrieval spatial convolution denoising Hyper-Cam LW imager Science Q
spellingShingle	hyperspectral thermal infrared field-based measurement temperature and emissivity retrieval spatial convolution denoising Hyper-Cam LW imager Science Q Lyuzhou Gao Liqin Cao Yanfei Zhong Zhaoyang Jia Field-Based High-Quality Emissivity Spectra Measurement Using a Fourier Transform Thermal Infrared Hyperspectral Imager
description	Emissivity information derived from thermal infrared (TIR) hyperspectral imagery has the advantages of both high spatial and spectral resolutions, which facilitate the detection and identification of the subtle spectral features of ground targets. Despite the emergence of several different TIR hyperspectral imagers, there are still no universal spectral emissivity measurement standards for TIR hyperspectral imagers in the field. In this paper, we address the problems encountered when measuring emissivity spectra in the field and propose a practical data acquisition and processing framework for a Fourier transform (FT) TIR hyperspectral imager—the Hyper-Cam LW—to obtain high-quality emissivity spectra in the field. This framework consists of three main parts. (1) The performance of the Hyper-Cam LW sensor was evaluated in terms of the radiometric calibration and measurement noise, and a data acquisition procedure was carried out to obtain the useful TIR hyperspectral imagery in the field. (2) The data quality of the original TIR hyperspectral imagery was improved through preprocessing operations, including band selection, denoising, and background radiance correction. A spatial denoising method was also introduced to preserve the atmospheric radiance features in the spectra. (3) Three representative temperature-emissivity separation (TES) algorithms were evaluated and compared based on the Hyper-Cam LW TIR hyperspectral imagery, and the optimal TES algorithm was adopted to determine the final spectral emissivity. These algorithms are the iterative spectrally smooth temperature and emissivity separation (ISSTES) algorithm, the improved Advanced Spaceborne Thermal Emission and Reflection Radiometer temperature and emissivity separation (ASTER-TES) algorithm, and the Fast Line-of-sight Atmospheric Analysis of Hypercubes-IR (FLAASH-IR) algorithm. The emissivity results from these different methods were compared to the reference spectra measured by a Model 102F spectrometer. The experimental results indicated that the retrieved emissivity spectra from the ISSTES algorithm were more accurate than the spectra retrieved by the other methods on the same Hyper-Cam LW field data and had close consistency with the reference spectra obtained from the Model 102F spectrometer. The root-mean-square error (RMSE) between the retrieved emissivity and the standard spectra was 0.0086, and the spectral angle error was 0.0093.
format	article
author	Lyuzhou Gao Liqin Cao Yanfei Zhong Zhaoyang Jia
author_facet	Lyuzhou Gao Liqin Cao Yanfei Zhong Zhaoyang Jia
author_sort	Lyuzhou Gao
title	Field-Based High-Quality Emissivity Spectra Measurement Using a Fourier Transform Thermal Infrared Hyperspectral Imager
title_short	Field-Based High-Quality Emissivity Spectra Measurement Using a Fourier Transform Thermal Infrared Hyperspectral Imager
title_full	Field-Based High-Quality Emissivity Spectra Measurement Using a Fourier Transform Thermal Infrared Hyperspectral Imager
title_fullStr	Field-Based High-Quality Emissivity Spectra Measurement Using a Fourier Transform Thermal Infrared Hyperspectral Imager
title_full_unstemmed	Field-Based High-Quality Emissivity Spectra Measurement Using a Fourier Transform Thermal Infrared Hyperspectral Imager
title_sort	field-based high-quality emissivity spectra measurement using a fourier transform thermal infrared hyperspectral imager
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/a0bf07ca9b9a4d3d85a456655c22026c
work_keys_str_mv	AT lyuzhougao fieldbasedhighqualityemissivityspectrameasurementusingafouriertransformthermalinfraredhyperspectralimager AT liqincao fieldbasedhighqualityemissivityspectrameasurementusingafouriertransformthermalinfraredhyperspectralimager AT yanfeizhong fieldbasedhighqualityemissivityspectrameasurementusingafouriertransformthermalinfraredhyperspectralimager AT zhaoyangjia fieldbasedhighqualityemissivityspectrameasurementusingafouriertransformthermalinfraredhyperspectralimager
_version_	1718431663024766976

Field-Based High-Quality Emissivity Spectra Measurement Using a Fourier Transform Thermal Infrared Hyperspectral Imager

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