In order to advance underwater computer vision and robotics from lab environments and clear water scenarios to the deep dark ocean or murky coastal waters, representative benchmarks and realistic datasets with ground truth information are required. In particular, determining the camera pose is essential for many underwater robotic or photogrammetric applications and known ground truth is mandatory to evaluate the performance of e.g., simultaneous localization and mapping approaches in such extreme environments. This paper presents the conception, calibration and implementation of an external reference system for determining the underwater camera pose in real-time. The approach, based on an HTC Vive tracking system in air, calculates the underwater camera pose by fusing the poses of two controllers tracked above the water surface of a tank. It is shown that the mean deviation of this approach to an optical marker based reference in air is less than 3 mm and 0.3{\deg}. Finally, the usability of the system for underwater applications is demonstrated.

翻译：为推进水下计算机视觉与机器人技术从实验室环境及清水场景向深海暗区或浑浊沿岸水域的拓展，需要具备真实标注信息的代表性基准测试集与数据集。其中，相机姿态解算是众多水下机器人或摄影测量应用的核心环节，在极端环境下评估即时定位与地图构建等方法的性能时，必须依赖已知的真实姿态信息。本文提出一种用于实时获取水下相机姿态的外部参考系统的设计原理、标定方法与实现方案。该系统基于空气介质中的HTC Vive追踪技术，通过融合水面上方两个控制器的追踪姿态，计算水下相机的姿态信息。实验表明，该方法与基于光学标志点的空气介质参考系统相比，平均偏差小于3毫米及0.3°。最后，本文验证了该系统在水下应用场景中的实用性。