Study of Underwater Large-Target Localization Based on Binocular Camera and Laser Rangefinder

Currently, for underwater close-range large-target localization, visual localization techniques fail since large targets completely occupy the camera’s field of view at ultraclose ranges. To address the issue, a multi-stage optical localization method combining a binocular camera and a single-point laser rangefinder is proposed in this paper. The proposed method comprises three parts. First, the imaging model of the underwater camera is modified, and a laser rangefinder is used to further correct the underwater calibration results of the binocular camera. Second, YOLOv8 is applied to recognize the targets to prepare for target localization. Third, extrinsic calibration of the binocular camera and laser rangefinder is performed, and a Kalman filter is employed to fuse the target position information measured by the binocular camera and laser rangefinder. The experimental results show that, compared with using a binocular camera alone, the proposed method can accurately and stably locate the target at close ranges with an average error of only 2.27 cm, without the risk of localization failure, and reduces binocular localization error by 90.57%.