Automated change detection for synthetic aperture sonar

Abstract

Change detection in seabed mapping is the process by which regions of interest are highlighted through the comparison of current scene data with historical data, and involves techniques that have application to a wide variety of disciplines and sensing modalities. Automated comparison of multi-temporal sidescan sonar images at the pixel (or parcel) level is challenging as the background pixels change due to a variety of factors. These include image resolution that degrades as a function of range, and temporal changes in the propagation medium and seafloor structure. With the advent of synthetic aperture sonars (SAS), which provide constant resolution over the swath and are deployed on actively navigated platforms capable of precise track repetition, the automated comparison of multi-temporal seabed images has in recent years been shown to be feasible. Change detection through the automated comparison of multi-temporal SAS imagery can be generally categorized as incoherent or coherent, where incoherent implies identifying changes in the amplitude, and coherent implies detecting changes in both amplitude and phase of the images. Utilizing the phase component may lead to detection of a physical disturbance in the scene. This presentation will provide an overview of the state-of-the-art of automated sonar seabed change detection.