Three-dimensional underwater image formation with inverse synthetic aperture sonar

Underwater three-dimensional imaging can be performed using several sonar sensors and interferometric methods. The problem with employng multiple sensors is the increased cost of hardware and synchronization issues. However, uncertainty reduces by using this method. An alternative way to reduce hardware is to utilize multipath circuits in the underwater environment. In this environment, multipath circuits are created by the impact of sound waves on the seafloor and sea surface. Seafloor reflections create direct-direct, direct-indirect, indirect-direct, and indirect-indirect circuits. In this paper, both methods of using and not using multipath circuits for three-dimensional imaging are presented in detail. Moreover, both approaches of using or not using virtual sources and cube target imaging will be carried out using the MATLAB software package. The type of sonar presented in this paper is an inverse synthetic aperture sonar. The results are comparable with those of the commercial systems. However, not all practical conditions are considered in this study in contrast with the commercial systems. Our contribution is the study of a novel method in three-dimensional imaging using virtual sources. This method has not been applied for this purpose before