In this paper, we present a complete refractive Structure-from-Motion (RSfM) framework for underwater 3D reconstruction using refractive camera setups (for both, flat- and dome-port underwater housings). Despite notable achievements in refractive multi-view geometry over the past decade, a robust, complete and publicly available solution for such tasks is not available at present, and often practical applications have to resort to approximating refraction effects by the intrinsic (distortion) parameters of a pinhole camera model. To fill this gap, we have integrated refraction considerations throughout the entire SfM process within the state-of-the-art, open-source SfM framework COLMAP. Numerical simulations and reconstruction results on synthetically generated but photo-realistic images with ground truth validate that enabling refraction does not compromise accuracy or robustness as compared to in-air reconstructions. Finally, we demonstrate the capability of our approach for large-scale refractive scenarios using a dataset consisting of nearly 6000 images. The implementation is released as open-source at: https://cau-git.rz.uni-kiel.de/inf-ag-koeser/colmap_underwater.

翻译：本文提出一个完整的折射式运动恢复结构（RSfM）框架，用于使用折射式相机设置（包括平板玻璃与半球罩式水下壳体）实现水下三维重建。尽管过去十年在折射式多视角几何领域取得了显著成就，目前仍缺乏一个鲁棒、完整且公开可用的解决方案，实际应用中往往不得不通过针孔相机模型的内参（畸变）参数近似折射效应。为填补这一空白，我们将折射考量整合至现有最先进开源SfM框架COLMAP的完整流程中。基于合成生成但具有照片级真实感且包含真实基准的图像进行的数值模拟与重建结果表明，相较于空气介质重建，启用折射效应并不会降低精度或鲁棒性。最后，我们采用包含近6000张图像的数据集验证了该方法在大型折射场景中的能力。实现代码已开源发布于：https://cau-git.rz.uni-kiel.de/inf-ag-koeser/colmap_underwater