Fused visible and infrared video for use in Wilderness Search and Rescue

Mini unmanned aerial vehicles (mUAVs) have the potential to assist wilderness search and rescue groups by providing a bird´s eye view of the search area. This paper proposes a method for augmenting visible-spectrum searching with infrared sensing in order to make use of thermal search clues. It details a method for combining the color and heat information from these two modalities into a single fused display to reduce needed screen space for remote field use. To align the video frames for fusion, a method for simultaneously pre-calibrating the intrinsic and extrinsic parameters of the cameras and their mount using a single multi-spectral calibration rig is also presented. A user study conducted to validate the proposed image fusion methods showed no reduction in performance when detecting various objects of interest in this single-screen fused display compared to side-by-side viewing. Most significantly, the users´ increased performance on a simultaneous auditory task showed that their cognitive load was reduced when using the fused display.