Forward-looking Sonar Image Mosaicking by Feature Tracking

High-frequency forward-looking sonars are appropriate for the operation or search close to the seabed. Constructing a panoramic mosaic not only facilitates an interpretation of the underwater environment, but also supports the vehicle's self-localization. In this paper, a method to register sonar sequences is proposed that is based on the feature tracking using the particle filtering. Our methods starts with the extraction of the intensity, the texture and the shape features from the unstructured seabed environment. Next a region of interest (ROI) is tracked until it disappears from the view field of an autonomous unterwater vehicle (AUV). Then, another ROI is selected and the tracking procedures are repeated. Experimental results show that (1) Feature tracking is feasible for the forward-looking sonar image mosaicking. (2) Fusion of the texture and the shape feature lead to a robust feature extraction method for more precise motion estimation. (3) The prior information on the AUV's movement is necessary for the tracking of highlighted regions.