Ship Hull Vinyl Dataset

An inside sweet water tank at the Institute for Maritime Technology (IMT) in Cape Town was used to take a controlled underwater dataset using a prototype sensor rig - 24 October 2023. The target scene is a life-sized photomosaic of the side of a commercial ship hull that IMT had previously taken when the ship was last in dry dock. The photomosaic is printed onto a large vinyl tarpaulin and hung along the side of the tank.<br><br>Because the tank platform is 1m from the surface of the water, two 3m PVC pipes were used to manoeuvre the rig through the water, seen below. The rig is moved horizontally along the side of the platform facing the vinyl surface. Marks were placed on the PVC pipes as a visual aid to keep the rig at a relatively constant depth when moving horizontally. Once at the end of the vinyl, the rig is lowered directly downward to the next marked depth and moved horizontally back along the platform, creating a square ‘C’ shape. The data collection starts at 0.5m depth and returns at 1m depth.<br>We provide the data in the form of ROS bags. The data is supplied in two formats: raw and pre-processed. The raw data has not been edited. The pre-processed data has been synchronized and images have been stereo rectified and undistorted. With the ROS bags we also include the stereo camera and stereo-inertial (camera-IMU) calibration output files in yaml format.The original calibration data for camera and stereo-inertial calibrations are also included in ROS bag format so that users can perform their own calibrations if desired. On the sister GitHub, in the Meta Data folder, we detail the data collection method in a PDF for contextual understanding of the dataset and provide the data sheets of the sensors used along with supporting code.

2023年10月24日，开普敦海事技术研究所（Institute for Maritime Technology, IMT）内部的淡水水槽被用于搭载原型传感器装置，采集受控水下数据集。本次采集的目标场景为IMT此前在该商用船体最后一次进干船坞时拍摄的等比例船体侧视照片镶嵌图（photomosaic），该镶嵌图被打印在大型乙烯基防水油布上，并沿水槽侧壁悬挂。

由于水槽平台距水面高度为1米，研究人员采用两根3米长的PVC管操控装置在水中移动（详见下文）。装置沿平台朝向乙烯基画面的一侧水平移动，PVC管上标记有刻度，用于辅助维持装置水平移动时的相对恒定深度。抵达乙烯基画面末端后，将装置垂直下放至下一个标记深度，再沿平台反向水平移动，形成“C”形扫描路径。数据采集始于0.5米水深，返程时则处于1米水深。

本次公开的数据集以ROS包（ROS bags）形式提供，分为原始与预处理两种格式。原始数据未经过任何编辑；预处理数据已完成时间同步，且图像经过立体校正与去畸变处理。随ROS包一同提供的还有yaml格式的立体相机与立体惯性（相机-惯性测量单元（Inertial Measurement Unit, IMU））标定输出文件。此外，还附带了相机与立体惯性标定的原始ROS包格式数据，以便用户按需自行开展标定工作。在配套的GitHub仓库的元数据文件夹中，我们以PDF文档详细说明了数据采集方法，便于使用者理解数据集的背景信息，同时还提供了所用传感器的参数表与配套代码。