Calibrated Long-Wave Infrared (LWIR) Thermal and Polarimetric Imagery of Small Unmanned Aerial Vehicles (UAVs) and Birds

Producing a set of well-calibrated imagery, both conventional LWIR thermal (watts/cm2-sr) and its corresponding polarimetric imagery (percent radiance polarized), helps evaluate the ability to distinguish between small UAVs and birds of similar size and dimensions.

Army Research Laboratory, Adelphi, Maryland

Currently, agencies within the Department of Defense (DOD) and the private sector are trying to develop techniques capable of detecting the presence of small unmanned aerial vehicles (UAVs) at ranges on the order of 1-5 km. Often complicating this effort is the presence of small birds of similar dimensions that are frequently mistaken to be small UAVs when imaged using various methodologies, such as visible, short-wave infrared (SWIR) and thermal imaging.

Initially, research was limited to long-wave infrared (LWIR) thermal imaging that, in theory, should be effective for both day- and night-time operation. The goal was to record a preliminary set of calibrated radiometric and polarimetric images in which both small UAVs and birds were present in the scene. Targets (i.e., UAV and/or birds) within each image were segmented and regions of interest (ROI) were generated by tracing a circumference around the object. Pixel values were then averaged to yield both a radiometric value (watts/cm2-sr) and a corresponding polarimetric value (percentage linearly polarized) in order to quantify similarities and differences between “generic” bird and UAV signatures.