High-precision underwater turbidity removal for 3D structured light reconstruction using division-of-focal-plane polarization

With the rapid advancement of marine technology, underwater 3D structured light reconstruction has emerged as a pivotal tool for ocean exploration, marine robotics, and underwater assembly. However, the aquatic environment typically contains numerous suspended particles that scatter and absorb signal light from the target, degrading underwater image quality and leading to unsatisfactory results with traditional image-based 3D reconstruction methods. To address this challenge, we have developed a temporal-multiplexing structured light system with polarization imaging to obtain dense and accurate target geometry information. Subsequently, we propose an underwater turbidity removal network based on this system. This network mitigates the impact of underwater turbidity on imaging accuracy and quality, significantly enhancing the precision and effectiveness of 3D reconstruction. Initially, we built a polarization system to capture fringe images of underwater objects at four different polarization angles. By calculating the second Stokes parameter and the degree of polarization, and then combining Canny features as input for the global contour capture block, we effectively extract the object’s contour information, restoring the fringe boundaries along its edges. Additionally, we introduce a fringe capture block to refine the boundaries of the fringe patterns, resulting in clearer internal reconstructions of the objects. By leveraging both the global contour capture block and the fringe capture block, we achieve high-precision underwater structured light reconstruction. Extensive experimental results demonstrate that our model achieves outstanding performance in terms of PSNR, SSIM, and LPIPS, with scores of 21.226, 0.969, and 0.050, respectively—significantly outperforming the reconstruction accuracy of state-of-the-art methods.