The Study Of Acoustical Lens Beam-forming And Acoustical Image Processing

High-resolution imaging sonar is widely applied to ocean monitoring and exploiting. In this thesis, two key-techniques of high-resolution imaging sonar are studied: beam-forming and acoustical image processing.Firstly, acoustical lens beam-forming applicable for high-resolution imaging is studied. The acoustical field is calculated from hybrid model. Then, it is simulated that how the beam-forming performance changed by the geometrical and material parameters of the lens and the temperature. The model is verified by experimentation.Secondly, an underwater-object localization method based on sequencal acoustical images is studied. Preprocessing and post de-noising are discussed with consideration of image characteristics. Tracing and objects localizationing are implemented via the procedure of: preprocessing, images accumulation, post de-noising.At last, acoustical image segmentation is studied. The methods which can be applied to images of forward looking sonar and side-scan sonar, are discussed respectively. The emphasis of this part is the method for segmenting bright-area and shadow-area in the side-scan sonar images.