Simulated Thermal Spectro-polarimetric Signatures of Water and Dark-painted Objects in Various Environmental Conditions

Report No. ARL-TR-5777
Authors: Melvin Felton
Date/Pages: September 2011; 18 pages
Abstract: The research presented in this report aims at elucidating the environmental factors that affect the spectro-polarimetric signatures of water and a dark-painted surface outdoors. We highlight the importance of thermal contrast between the object of interest and its optical background; explicitly present the analysis for four environmental scenarios (clear sky and dry atmosphere, clear sky and humid atmosphere, altostratus clouds, and cumulus clouds); and for each scenario, present the angular dependence of the degree of linear polarization for various band-averages within the two infrared (IR) imaging windows (3–5 and 8–12 μm). It is shown that midwave IR (MWIR) polarimetric contrast between an object and its visible background in a scene can be reduced in clear sky conditions due to the competing components of reflected solar radiance and radiance emitted from the object while the same contrast may be increased when cloudy conditions nullify the scattered solar radiance. In addition, long-wave IR (LWIR) polarimetric contrast is highest for clear sky conditions and may be reduced as the contribution from the optical background increases.
Distribution: Approved for public release
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Last Update / Reviewed: September 1, 2011