Underwater large field of view 3D imaging based on fisheye lens

Abstract

As for the 3D imaging of seabed topography, seabed sunken ships and large underwater buildings, the field of view is a significant technical index of the 3D imaging system. In this paper, a binocular vision imaging system based on fisheye lens is applied to satisfy the requirements for 3D imaging of large underwater scenes. Considering the severe image distortion caused by the large wide-angle of fisheye lens and the failure of pinhole imaging model underwater, the imaging process of underwater fisheye camera is re-described through the parametric representation of four-dimensional light field, and the multi-layer refraction imaging model of underwater binocular stereo vision is established based on fisheye camera. A conversion imaging model is constructed to convert the corrected underwater fisheye image into the equivalent image taken in the air. Combined with the existing stereo matching methods, the converted images realize the 3D reconstruction of a large-scale underwater scene. Experimental results show that the corrected underwater fisheye images have a small average reprojection error, which evidences the effectiveness of the proposed calibration method. In the experiment of 3D reconstruction for the large scene composed of multiple underwater ceramic discs, the reconstructed targets have good 3D imaging shapes, which indicates the developed underwater binocular fisheye camera imaging system has the ability to perform 3D imaging and make observations of large underwater scenes.