AUV Imagery from Gippsland Basin III (GA355 Long-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 Autonomous Underwater Vehicle (AUV) Phoenix and AUV Sirius on survey GA-355 conducted 18-22 February 2016 on the M.V. Dell Richey II. The AUV Phoenix was the main system used to collect imagery analysed in the GMEM project using the two loop pattern (Figure 1) from previous surveys (GA-350 and GA-353). The AUV Sirius was deployed to collect concurrent dense image grids at selected stations (05, 08, 37, 45) and to provide a back-up to the Phoenix in the event of equipment issues. This occurred at Stations 40 and 41, and as such the Sirius collected images in the two-loop pattern. In addition to the main study area for the GMEM, the AUV Sirius was also deployed outisde Devonport, Tasmania in order to establish workflow, fine-tune technical aspects, and census scallop beds that were known to be in ill health. Imagery from these stations are included in sub-folder Devonport_Sites. Due to strong currents and possible navigation issues, some of the AUV paths deviated from the planned path and also varied in altitude. Nevertheless, the georeferencing of images released in this data package reflects the actual position of the AUV during image acquisition. Post-processing included image colour-balancing and simultaneous localisation and mapping (SLAM) processing of the stereo imagery to improve georeferencing of the imagery. The optical imagery is provided in zip files as geotiffs (individual colour-corrected images), mosaics, and mesh (3D seafloor reconstructions)