Abstract

Abstract
This work addresses reconstructing an ancient mining site in three-dimensional (3D) modelling with robotic systems, processing the information from two visible spectrum cameras. The developed solution, GeoTec System, was validated in an underground environment in the Monastery of Tibães (Braga, NW Portugal). This study was developed under the MineHeritage project's scope, aiming to attain society on the importance of raw materials across a historical approach. The outputs acquired from the datasets developed in a successful 3D reconstruction of the main gallery and secondary tunnels of the Aveleiras mine in Tibães. However, the investigation is still ongoing to contribute to applying 3D reconstruction technologies, GIS-based mapping and geovisualization techniques in the underground heritage environment.

Abstract
Gamma radiation over the Atlantic Ocean was measured continuously from January to May 2020 by a NaI(Tl) detector installed on board the Portuguese navy's ship NRP Sagres. Enhancements in the gamma radiation values are identified automatically by an algorithm for detection of anomalies in mean and variance as well as by visual inspection. The anomalies are typically +50% above the background level and relatively rare events (similar to<10% of the days). All the detected anomalies are associated with simultaneous precipitation events, consistent with the wet deposition of scavenged radionuclides. The enhancements are detected in the open ocean even at large distances (+500 km) from the nearest coastline. Back trajectories reveal that half of these events are associated with air masses experiencing continental land influences, but the other half do not display evidence of recent land contact. The enhancements in gamma radiation very far from land and with no evidence of continental fetch from back trajectories are difficult to explain as resulting only from radionuclides with a terrestrial source such as radon and its progeny. Further investigation and additional measurements are needed to improve understanding on the sources of ambient radioactivity in the open ocean and assess whether gamma radiation in the marine environment is influenced not only by radionuclides of terrestrial origin, but also cosmogenic radionuclides, like Beryllium-7, formed in the upper atmosphere but with the ability to be transported downward and serve as a tracer of the aerosols to which it attaches. Plain Language Summary Radioactive elements such as the noble gas radon and those produced by its radioactive decay are naturally present in the environment and used as tracers of atmospheric transport and composition. In particular, the noble gas radon, being inert and of predominantly terrestrial origin, is used to identify pristine marine air masses with no land contamination. Precipitation over land typically brings radon from the atmosphere to the surface, enhancing gamma radiation on the ground, but such enhancements have not been identified before nor expected over the ocean due to the low amount of radon typical of marine air masses. Here we report, for the first time, gamma radiation enhancements associated with precipitation in the oceanic environment, using measurements performed over the Atlantic Ocean in a campaign onboard the Portuguese navy ship NRP Sagres.

Abstract
Highlights What are the main findings? The SLAM method, based on the registration of 3D profiling sonar scans using the 3DupIC method, avoids the construction of submaps and thereby overcomes the limitations of other state-of-the-art approaches. Simultaneous optimization of the trajectory and extrinsic parameters, using the proposed SLAM and calibration method, ensures high accuracy in trajectory and map estimation. What is the implication of the main finding? Direct registration of raw scans supports two distinct applications. On the one hand, it enables pose estimation through odometry. On the other hand, it provides loop-closure constraints for the SLAM process. 3D profiling sonars are highly effective sensors for mapping, localization, and SLAM applications. This demonstration is particularly important as newer, smaller, and more affordable sonars in this category become available, contributing to their wider adoption.Highlights What are the main findings? The SLAM method, based on the registration of 3D profiling sonar scans using the 3DupIC method, avoids the construction of submaps and thereby overcomes the limitations of other state-of-the-art approaches. Simultaneous optimization of the trajectory and extrinsic parameters, using the proposed SLAM and calibration method, ensures high accuracy in trajectory and map estimation. What is the implication of the main finding? Direct registration of raw scans supports two distinct applications. On the one hand, it enables pose estimation through odometry. On the other hand, it provides loop-closure constraints for the SLAM process. 3D profiling sonars are highly effective sensors for mapping, localization, and SLAM applications. This demonstration is particularly important as newer, smaller, and more affordable sonars in this category become available, contributing to their wider adoption.Abstract High resolution underwater mapping is fundamental to the sustainable development of the blue economy, supporting offshore energy expansion, marine habitat protection, and the monitoring of both living and non-living resources. This work presents a pose-graph SLAM and calibration framework specifically designed for 3D profiling sonars, such as the Coda Octopus Echoscope 3D. The system integrates a probabilistic scan matching method (3DupIC) for direct registration of 3D sonar scans, enabling accurate trajectory and map estimation even under degraded dead reckoning conditions. Unlike other bathymetric SLAM methods that rely on submaps and assume short-term localization accuracy, the proposed approach performs direct scan-to-scan registration, removing this dependency. The factor graph is extended to represent the sonar extrinsic parameters, allowing the sonar-to-body transformation to be refined jointly with trajectory optimization. Experimental validation on a challenging real world dataset demonstrates outstanding localization and mapping performance. The use of refined extrinsic parameters further improves both accuracy and map consistency, confirming the effectiveness of the proposed joint SLAM and calibration approach for robust and consistent underwater mapping.