Atmospheric Compensation of Thermal Infrared HyperspectralImagery with the Emissive Empirical Line Method and the In-SceneAtmospheric Compensation Algorithms: A Comparison

摘要

The in-scene atmospheric compensation (ISAC) algorithm of Young et al. (2002) [ 14] (and as implemented in theENVI software system [16] as‘ Thermal Atm Correction') is commonly applied to thermal infrared multi- andhyperspectral imagery (MSI and HSI, respectively). ISAC estimates atmospheric transmissivity and upwelling radianceusing only the scene data. The ISAC-derived transmissivity and upwelling radiance are compared to those derived fromthe emissive empirical line method (EELM), another in-scene atmospheric compensation algorithm for thermal infraredMSI and HSI data. EELM is based on the presence of calibration targets (e.g., panels, water pools) captured in thespectral image data for which the emissivity and temperature are well known at the moment of MSI/HSI dataacquisition. EELM is similar in concept to the empirical line method (ELM) algorithm commonly applied tovisible/near-infrared to shortwave infrared (VNIR/SWIR) spectral imagery and is implemented as a custom ENVI plug-in application. Both ISAC and EELM are in-scene methods and do not require radiative transfer modeling. ISAC andEELM have been applied to airborne longwave infrared (LWIR; ~7.5 μm to ~13.5 urn) HSI data. Captured in theimagery are calibration panels and/or water pools maintained at different temperatures facilitating the application ofEELM. Overall, the atmospheric compensation parameters derived from the two methods are in close agreement: theEELM-derived ground-leaving radiance spectra generally contain fewer residual atmospheric spectral features, although1SAC sometimes produces smoother ground-leaving radiance spectra. Nonetheless, the agreement is viewed asvalidation of ISAC. ISAC is an effective atmospheric compensation algorithm that is readily available to the remotesensing community in the ENVI software system. Thus studies such as the present testing and comparing ISAC to othermethods are important. The ISAC and EELM algorithms are discussed as are the airborne LWIR and simulated HSI datato which they are applied. Also presented are analyses and comparisons of the retrieved transmissivity and upwellingradiance terms.