Seabed imagery from IN2017_V01, Sabrina Seafloor survey, East Antarctica

Six camera tow transects were completed during survey IN2017-V01 on the RV Investigator in January to March 2017. This survey focussed on the upper slope and outer continental shelf on the Sabrina Coast seafloor in East Antarctica. Camera tows targeted seafloor depths between 480 and 1680 m. Imagery was collected using the Marine National Facilities Deep Tow Camera. This system collects oblique downward facing still images with a Canon 1DX and high definition video with a Canon C300. Four DSP&L 3150 High Output SeaLite Sphere lights were used, with MicroSeaLasers providing a 10cm scale guide on the images. Several sensors are also attached to the towed body, including a SBE 37 for CTD measurements, a Kongsberg Mesotech 1007D altimeter, a Druck PMP 5074 pressure sensor and two Sonardyne USBLs for locational accuracy of the towed body. The USBL failed for tow A008CAM02, with locations recorded as ships position instead and camera position based on layback calculations. Images failed to record on A004CAM01, with only 2 images saved. Due to a timing error between the images and the other sensors, there is an offset between the CTD, altimeter and pressure data and the images. This is currently being resolved by the MNF. Tows were designed to run down slope to reduce potential for colliding with the bottom. All tows were run with a ship speed over the ground of approximately 2 kt. All still images were saved in jpeg format with video footage recorded to HD1080i50 format. The video data is unclipped and includes descent and ascent in the water column. Following collection still images were colour corrected in Adobe Photoshop to remove the blue bias.

2017年1月至3月，在‘调查者号’科考船（RV Investigator）的IN2017-V01航次中，共完成了6次摄像拖曳测线作业。本次航次的研究区域为东南极洲萨布里娜海岸（Sabrina Coast）的海底上陆坡与外大陆架区域。摄像拖曳作业的目标海底水深范围为480米至1680米。影像数据由海洋国家设施深拖摄像系统（Marine National Facilities Deep Tow Camera）采集。该系统搭载佳能1DX（Canon 1DX）相机采集斜向下拍摄的静态图像，并使用佳能C300（Canon C300）摄像机采集高清视频。本次作业使用了4台DSP&L 3150高输出型SeaLite Sphere水下照明灯，同时配备MicroSeaLasers为图像提供10厘米比例尺标尺。拖曳体上还搭载了多款传感器，包括用于温盐深（Conductivity-Temperature-Depth, CTD）测量的SBE 37传感器、Kongsberg Mesotech 1007D高度计、Druck PMP 5074压力传感器，以及两台用于提升拖曳体定位精度的Sonardyne超短基线（Ultra-Short BaseLine, USBL）定位系统。在A008CAM02次拖曳作业中，USBL定位系统失效，此时定位数据直接记录为船位，摄像位置则通过拖缆滞后距离计算得出。A004CAM01次拖曳作业未成功采集图像，仅保存了2张静态照片。由于图像采集与其他传感器之间存在计时误差，温盐深、高度计及压力传感器数据与图像之间存在偏移，目前该问题正由海洋国家设施（MNF）团队进行修复。拖曳作业均沿斜坡向下进行，以降低与海底碰撞的风险。所有拖曳作业的船舶对地航速均约为2节（kt）。所有静态图像均以JPEG格式存储，视频素材则以HD1080i50格式录制。视频数据未进行剪辑，包含了水下升降过程的影像。采集完成后，科研人员使用Adobe Photoshop对静态图像进行了色彩校正，以消除蓝色色偏。