Experiments in Detecting Obscured Objects Using Longwave Infrared Polarimetric Passive Imaging

Polarization has been shown to improve object-clutter discrimination in longwave infrared imaging, particularly if the object and clutter have the same apparent surface temperature and the viewing angle relative to an object's surface is off normal. This work describes experimentation to investigate the feasibility of using polarimetric infrared imagery to enhance object-clutter discrimination when the object is hidden by foliage. Many obscurations have small gaps where optical signatures from background objects can be partially seen. In long range imaging, large pixel size typically creates heterogeneous pixel mixtures consisting of multiple material surfaces. This mixture degrades an object's signature; however, due to the significant polarization contrast from the materials, object-clutter discrimination is still possible. Methodology and results from controlled experiments are presented herein which demonstrate the potential capability of object detection using polarization sensitive imagery.