AUV Imagery from Gippsland Basin (GA353 - 'Short-term after' survey)

This dataset is part of the Gippsland Marine Environmental Monitoring (GMEM) project. The GMEM was developed in response to stakeholder concerns from the fisheries industry about a Geoscience Australia seismic survey in the Gippsland Basin (GA352 in April 2015), in addition to a broader need to acquire baseline data to be used to quantify impacts of seismic operations on marine organisms. A component of this study was to acquire images of the seafloor before and after the seismic survey for analysis of potential impacts of seismic operations on scallops. This dataset contains information collected from the AUV-Phoenix on survey GA-353 conducted 19-25 June 2015. The Phoenix is an Iver AUV operated by Australian Marine Ecology Pty Ltd and the University of Sydney (Australian Centre for Field Robotics). It includes a stereo camera system (i.e. two cameras), a USBL, and a sidescan sonar. Stereo image pairs were collected at a rate of 2 Hz with a target altitude of 2 m above the seabed and speed of 1 m s-1 (2 knots) using high sensitivity CCD cameras (Allied Vision Manta G-145C, resolution of 1388 x 1038 pixels). Illumination was by two strobes mounted in the fore and aft-sections of the vehicle and synchronised with the cameras. The camera lens and stereo orientation properties were calibrated in a pool immediately prior to the survey. The Phoenix returned usable still images at 12 sites, but strong currents resulted in truncated transects due to difficulty diving on Stations 14, 37, and 47, and strobe failure on Stations 40 and 47 resulted in reduced image quality. For each station, this dataset contains post-processed geotiffs acquired from a single AUV camera, track files, and a compressed mosaic of combined images. A Word file provides additional data about the folder structure, file types, and post-processing.

本数据集属于吉普斯兰海洋环境监测项目（Gippsland Marine Environmental Monitoring, GMEM）。该项目的设立，一方面旨在回应渔业行业利益相关方对2015年4月于吉普斯兰盆地开展的澳大利亚地球科学局（Geoscience Australia）地震勘探活动（GA352）的关切，另一方面则为满足获取基线数据的广泛需求，以量化地震作业对海洋生物的影响。本研究的核心内容之一，是采集地震勘探前后的海底图像，用于分析地震作业对扇贝的潜在影响。
本数据集包含2015年6月19日至25日开展的GA-353勘探中，从凤凰号自主水下航行器（AUV-Phoenix）采集到的全部数据。该航行器为Iver系列自主水下航行器，由澳大利亚海洋生态有限公司（Australian Marine Ecology Pty Ltd）与悉尼大学澳大利亚现场机器人中心（Australian Centre for Field Robotics）共同运营，搭载立体相机系统（即两台相机）、超短基线定位系统（Ultra-Short Baseline, USBL）及侧扫声呐。
研究采用高灵敏度CCD相机（Allied Vision Manta G-145C，分辨率为1388×1038像素），以2赫兹的帧率采集立体图像对，设定作业高度为海底上方2米，航行速度为1米每秒（2节）。照明由安装在航行器前部与后部的两台频闪灯提供，并与相机实现同步。勘探开展前，研究人员已在水池中完成相机镜头及立体定位参数的校准工作。
凤凰号在12个测点采集到了可用的静态图像，但受强海流影响，14、37、47号测点的航行断面出现截断；此外40号与47号测点发生频闪灯故障，导致图像质量下降。本数据集为每个测点提供了从单台AUV相机导出的经过后处理的GeoTIFF图像、航迹文件，以及拼接图像的压缩镶嵌图。另有一份Word文档，详细说明了文件夹结构、文件类型及后处理流程。