Equipment and Datasets – Santorini

EQUIPMENT AND DATASETS - SANTORINI SUMMER SCHOOL

DRONES

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GEOSLAM

GeoSlam is a handheld laser scanner with LiDAR sensor for acquiring 3D point clouds and generating geo-referenced 3D models through SLAM algorithm for multidisciplinary applications (e.g. slope stability, 3D geomorphic processes, forestry measurements, plant biomass calculations, urban planning, mapping underground environnements). It acquires 300k points per second, up to a maximum distance of 100 m and with precision less than 3 cm, providing aligned and coloured 3D point clouds and panoramic imagery sample points. During the Santorini summer school, the research team performed a number of GeoSlam surveys involving all students in field activities.

Data collected along the red beach were processed during a dedicated laboratory session. The BridgET research team involved in in the project is actively working on combining drone, geoslam and multibeam data to obtain a seamless 3D model of the red beach and its offshore domain.

MULTIBEAM ECHOSOUNDER

R2Sonic 2022 is a high-performance multibeam echosounder system designed for underwater mapping and surveying. It uses advanced sonar technology to create detailed and accurate seafloor 3D models, featuring a variable swath width capability that allows users to adjust the beam angles. It also has advanced features including real-time water column imaging, automated data processing, integrated data quality control tools, and the opportunity to operate in multispectral modeR2Sonic 2022 is built with a rugged and compact design, making it suitable for various types of vessels and survey operations.

We planned to use this equipment during the summer school, but due to bad weather conditions we did not manage to carry out the survey. However, the system was showed to the students, and a “dry installation” was simulated during the laboratory activity. Existing high-quality multibeam dataset acquired offshore the Santorini Red Beach during a previous project led by the NKUA was made available  for the data processing during the laboratory session, to create a submarine geospatial dataset suitable for integration with drone data collected offshore

AMBIENT NOISE

In Santorini, we used a 1 Hz Lennartz 3-component sensor connected to a Cityshark seismic station for the H/V ambient noise measurements. The Cityshark recordings lasted 20 mn with a sampling rate of 200 Hz (sample of 0.005 s). Those measurements are then processed in the frequency range, to compute horizontal-to-vertical spectral ratios that help identify the fundamental resonance frequency of the ground, which can be used to estimate its thickness (for the upper soft layer part).

360° CAMERA

360° Cameras are a versatile tool to shoot footage which can be used in VR applications. The used Insta360 Pro 2 camera is equipped with six 4K lenses which produce videos and photos that can be stitched to native 8k 360° footage. The resulting files can then be edited as a VR 360 Video, which enables the viewer to choose own perspectives within a video. Furthermore, videos and photos are the basis to built immersive 360° virtual tours. So far, this technology is most often used by real estate companies, the e-commerce sector and by GoogleStreetView for geospatial data. The opportunities for using 360° imagery for teaching in a virtual reality framework are endless and are evolving constantly.

During the summer school, we used the Insta360 Pro 2 to shoot videos and photos of key research areas. The resulting products are 360° videos and images for virtual tours. These products will contribute to further deliverables like a ”virtual cruise” and an immersive guideline to produce seamless land to sea geological models.

ROV

The future of ocean research and exploration lies in robotics: marine robotic systems can be deployed at depths and in environments that are out of direct reach for humans, they can work around the clock, and they can be autonomous, freeing up time and money for other activities. The two types of robots that currently make the biggest difference in ocean exploration are Remotely Operated Vehicles (ROVs) and Autonomous Underwater Vehicles (AUVs). The BluROV we used during the summer school is a smooth, stable, and highly maneuverable observational ROV, equipped with six thrusters, a rugged frame, and quick-swappable batteries. It is ideal for operations in shallow to moderate waters, with a standard 100 m depth rating.

The offshore of Kokkinopetra beach was explored during field activities.The NKUA has been and is currently active in performing surveys all around the Santorni offshore in a number of national and international funded projects.