Figure 1
Flowchart illustrating the three main stages of surveying an underwater cultural heritage site using underwater drones.
Figure 2
Map of the Phournoi archipelago, North Aegean Sea, Greece, and the locations of the two case studies (Late Roman shipwreck site and anchorage site) presented in the paper.
Figure 3
Left: The underwater drone Blueye X3 ready for deployment. Right: The underwater drone’s full photogrammetric setup.
Figure 4
Calibration data from the underwater drone’s internal camera.
Figure 5
The underwater drone’s trajectories over the wreck site. The white dashed line shows the path of the vehicle, which follows the terrain of the site, while keeping a constant altitude h thanks to the DVL sensor. The dimensions of the robot with respect to the wreck site are distorted for visualization purposes.
Figure 6
Up: The field of view of the three cameras of the photogrammetric setup. Down: Snapshots from the photogrammetric recording of the byzantine wreck by the underwater drone.
Figure 7
Up: Real-time map creation of the wreck through ORB-SLAM3 implementation. Down: Synchronized footage from the trifocal camera system of the underwater drone.
Figure 8
Results of the 3D reconstruction of the byzantine Late Roman wreck (in overview and detail).
Figure 9
Four different anchor types found at the bay of Kamari. From left to right: a) lead stock of a Roman anchor, b) grapnel anchor of the Ottoman period, c) admiralty type anchor (18th–19th century), d) composite stone anchor (prehistoric).
Figure 10
The DTX2 underwater drone surveying the Kamari anchorage site.
Figure 11
Left: the transects of the underwater drone following the bathymetry of the anchorage area, at a constant diving altitude of 5 meters above the seabed. Right: the localization of the 21 anchors off the shore of the bay of Kamari and the existing bathymetric model provided by RPM Nautical Foundation.
Figure 12
Georeferenced orthophotomosaic of the anchorage site of Kamari.
Figure 13
Anchors distribution map at the Kamari bay.