Interferometric Synthetic Aperture Sonar Three-dimensional Imaging Study

Interferometric Synthetic Aperture Sonar provides a 3-dimensional image of the target area through the phase difference between two 2-dimensional images obtained by the SAS processing, which is helpful and meaningful to sea-route measurement, terrain mapping, underwater archaeology, salvage, the oil industry and the identification of the mine. So it will be significant to the economic construction and national defense of our country to research the InSAS.At the beginning, the SAS image processing technique has been addressed, then the SAS echo model of point target is introduced and the imaging algorithms including beamforming algorithm, Range-Doppler algorithm and wavenumber algorithm are deeply discussed. The Displaced Phase Center motion compensation method based on the echo data is also analyzed.The Interferometric signal processing technique is comprehensively studied. The image registration, the noise-filtering of the interferogram and the 2-dimensional phase unwrapping of the interferogram are fully investigated step by step.Two image algorithms, the geometry-based algorithm and co-efficient-based algorithm are discussed, and the accuracy of these two algorithms is validated through the simulated data.The phase characteristic of the phase image is analyzed. The pixel-average algorithm, the conditional neighborhood-averaging algorithm, the morphological and modified median filtering algorithm and the vector-filtering algorithm are introduced and compared.The 2-dimensional phase unwrapping problem is comprehensively addressed, and the Goldstein's Branch-Cut algorithm, the Quality-guided algorithm, Minimum Discontinuity algorithm and Least Square algorithm are stressed. Finally, the performance comparison of these phase-unwrapping algorithms is given.In the end, the whole work is concluded and the implications for future research are discussed.