On detecting surface and sub-surface bodies in water by virtue of their surface and water column wakes

This paper presents theoretical and experimental results of detection and parameterization of moving bodies and scuba divers based on their surface and water column signatures under Hudson River estuary conditions. (1) Theoretical and experimental (SIT DL Towing Tank) estimates of wake characteristics for bodies of interest are carried out. (2) The IR-images of ship wakes at the surface of the Hudson River estuary show that a surface ship wake under some natural illumination conditions has different IR-images in different wave length bands. The carried out analysis of thermal surface wakes demonstrates qualitative and quantitative consistency the Hudson River data with the theoretical estimates. The developed coupled bubble-turbulence wake theory predicts the bubble-wake characteristics versus the wake source parameters. The SIT Towing Tank data demonstrate that the coupled bubble-turbulence theory is reliable. (3) The scuba diver detection is presented by results of experimental study of the wake turbulence, the bubble-wake and its surface manifestations in visual and IR bands in the SIT Towing Tank and the Hudson River. The detection, recognition and tracking in visible and infrared bands of ships and their wakes, and scuba divers, using real-time computer processing are also discussed.