Piecewise Surface Fitting Method for Complex Image Registration of Interferometric Synthetic Aperture Sonar

  Objectives  Complex image registration is crucial in interferometric synthetic aperture sonar (InSAS) signal processing. The registration quality directly influences the generation of interferogram and the subsequent reconstruction of digital elevation model. The traditional global polynomial surface fitting method has the disadvantage of low accuracy for large scene InSAS images. Therefore, a registration method based on piecewise surface fitting is proposed to overcome the problem.

  Methods  Firstly, the whole image is partitioned into several pieces along range direction with partly overlapped. Then, polynomial surface fitting is performed using control points in each piece. Finally, the global offset surface is obtained by merging those local surface fitting results.

  Results  Through the simulation and real data experiments, the accuracy of complex image registration using the proposed method is higher than the result of global polynomial surface fitting method.

  Conclusions  The evaluation has been carried out with the root mean squared error, correlation coefficient, residue numbers, which indicates the validity of the proposed approach.