A Method for Automatic Detection of Underwater Objects using Forward-looking Imaging Sonar

A method for automatic detection or recognition using high-frequency forward-looking imaging sonar is proposed. The method includes segmentation of an underwater object's echo shape or its acoustic shadow shape. For accuracy of segmentation, some constraints were assumed on the underwater ground and the sonar's pose. The separated shape was compared to simulated reference shapes to know its orientation or identity by the shape matching method that use shape context concept. An experiment conducted in a wave tank validated the method qualitatively. The method can be applied to an AUV's object-searching applications.