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Keywords = 3D mobile survey system

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40 pages, 3593 KB  
Review
Building Aerial Corridors for 6G Sky Infrastructure
by Sofia Anagnostou, Abdul Saboor, Harris K. Armeniakos, Fotios Katsifas, Konstantinos Maliatsos and Zhuangzhuang Cui
Electronics 2026, 15(9), 1773; https://doi.org/10.3390/electronics15091773 - 22 Apr 2026
Abstract
The sixth-generation (6G) mobile networks are envisioned to deliver seamless three-dimensional(3D) coverage from ground to sky and vice versa. In parallel, aerial corridors are emerging to elevate ground-based transportation into the air, enabling smart air mobility for unmanned aerial vehicles (UAVs). The convergence [...] Read more.
The sixth-generation (6G) mobile networks are envisioned to deliver seamless three-dimensional(3D) coverage from ground to sky and vice versa. In parallel, aerial corridors are emerging to elevate ground-based transportation into the air, enabling smart air mobility for unmanned aerial vehicles (UAVs). The convergence of this intelligent transportation system (ITS) with 6G introduces new challenges: how to ensure reliable, efficient connectivity within aerial corridors, and how these corridors can serve as foundational sky infrastructure to advance the 6G ecosystem. This paper presents a comprehensive survey that systematically presents aerial corridors as integrated 6G sky infrastructure, unifying corridor geometry, network architecture, channel modeling, and key enabling technologies within a single framework. It conceptualizes the aerial corridor as a tube-shaped, multi-lane, bidirectional structure to manage drone-based roles, including user equipment (UE), base stations (BS), and communication relays. To support this vision, key enablers such as air-to-ground channel modeling and integrated sensing and communication (ISAC) are investigated. The proposed infrastructure aligns with the IMT-2030 vision, supporting machine-type communication, ubiquitous connectivity, and immersive services in regulated aerial space. Full article
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16 pages, 1299 KB  
Article
Urology Training Across Borders: An International Survey of Residents’ Experiences, Perceptions, and Expectations
by Andrea Alberti, Rossella Nicoletti, Anna Luisa Heinrichs, Julian Peter Struck, Petros Sountoulides, Francesco Curto, Sergio Serni, Georgios Chasiotis, Olumide Farinre, Harshit Garg, Clément Klein, Gaelle Margue, Amanda A. Myers, Nikolaos Pyrgidis, Roberto Contieri, Ioana Fugaru, Lazaros Tzelves, Alessandro Uleri, Wilbert Fana Mutomba, Dimitrios Diamantidis, Jean de la Rosette, Maria Pilar Laguna, Jack M. Zuckerman, Philippe E. Spiess, Henry H. Woo, Stavros Gravas and Mauro Gacciadd Show full author list remove Hide full author list
Soc. Int. Urol. J. 2026, 7(2), 24; https://doi.org/10.3390/siuj7020024 - 17 Apr 2026
Viewed by 163
Abstract
Background/Objectives: Urology residency training widely varies across countries, and evidence comparing residents’ experiences at an international level is limited. This study reports the results of an international survey of urology residents from different countries worldwide, aiming to characterize training environments, educational exposure, [...] Read more.
Background/Objectives: Urology residency training widely varies across countries, and evidence comparing residents’ experiences at an international level is limited. This study reports the results of an international survey of urology residents from different countries worldwide, aiming to characterize training environments, educational exposure, and trainee expectations across diverse healthcare systems. Methods: A 39-item online survey was administered to urology residents during the Société Internationale d’Urologie (SIU) Regional Meeting (Florence, November 2024), assessing demographics, training exposure, educational resources, workload, satisfaction, and career perspectives. The results were compared between trainees at different postgraduate years (PGYs) to explore associations for key outcomes. Results: Overall, 208 urology residents from 21 countries completed the survey. Most residents were actively involved in research (76.4%), although confidence in independent scientific production was moderate (significantly lower among junior trainees). Surgical exposure increased with PGY, with good experience in endoscopy but limited hands-on exposure and expected autonomy in laparoscopic, robotic, and major open surgery. Despite high overall satisfaction with urology, residents described heavy workloads, inconsistent access to structured teaching and international fellowships, and a long-term shift in career expectations toward private practice. Conclusions: Urology residents worldwide report high engagement in research, strong satisfaction with their specialty choice, and interest in international mobility. Nonetheless, persistent disparities in surgical exposure, research confidence, workload, and gender representation highlight the need for competency-based curricula, structured mentorship, and improved training organization to promote equitable and high-quality urology education globally. Full article
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47 pages, 3286 KB  
Review
LiDAR-Based Road Surface Damage Classification: A Survey
by Trevor Greene, Meisam Shayegh Moradi, Muhammad Umair, Nafiul Nawjis, Naima Kaabouch and Timothy Pasch
Sensors 2026, 26(8), 2338; https://doi.org/10.3390/s26082338 - 10 Apr 2026
Viewed by 239
Abstract
Unlike image-only systems that falter in shadows, glare, and low contrast, LiDAR directly records surface geometry and supports depth-aware quantification. This survey examines LiDAR-based road surface damage classification across the entire pipeline, encompassing acquisition with mobile and terrestrial laser scanning, preprocessing and representation [...] Read more.
Unlike image-only systems that falter in shadows, glare, and low contrast, LiDAR directly records surface geometry and supports depth-aware quantification. This survey examines LiDAR-based road surface damage classification across the entire pipeline, encompassing acquisition with mobile and terrestrial laser scanning, preprocessing and representation choices, supervised, semi-supervised, and unsupervised learning techniques, as well as multisensor fusion at early, mid, and late stages. A consistent thread is measurement, not just detection: we describe how LiDAR damage classification maps to agency practices such as the Distress Identification Manual and the Pavement Condition Index. We summarize datasets and evaluation protocols for detection, segmentation, 3D reconstruction, and ride quality. We outline practical concerns for corridor-scale deployment: calibration and timing, intensity normalization, tiling/streaming, and runtime budgeting. The review concludes with open problems and outlines directions for robust, severity-aware, and scalable field systems. Full article
(This article belongs to the Section Remote Sensors)
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28 pages, 28199 KB  
Article
Augmented Reality as a Tool for 5G Learning: Interactive Visualization of NSA/SA Architectures and Network Components
by Nathaly Orozco Garzón, David Herrera, Angel Gomez, Pablo Plaza, Henry Carvajal Mora, Roberto Sánchez Albán, José Vega-Sánchez and Paola Vinueza-Naranjo
Informatics 2026, 13(4), 58; https://doi.org/10.3390/informatics13040058 - 3 Apr 2026
Viewed by 320
Abstract
The rapid advancement of digital and mobile technologies has reshaped the educational landscape, fostering the adoption of interactive and learner-centered methodologies. Among these, immersive technologies such as Augmented Reality (AR), when coupled with next-generation wireless communication systems, hold the potential to revolutionize knowledge [...] Read more.
The rapid advancement of digital and mobile technologies has reshaped the educational landscape, fostering the adoption of interactive and learner-centered methodologies. Among these, immersive technologies such as Augmented Reality (AR), when coupled with next-generation wireless communication systems, hold the potential to revolutionize knowledge acquisition and student engagement. In this paper, we present the design and development of an AR-based educational tool specifically oriented to teaching concepts of fifth-generation (5G) mobile networks. The tool provides a real-time interactive visualization of 3D network components on mobile devices, enabling learners to explore 5G NSA/SA architectures in an accessible manner with real-world environments through mobile devices and their integrated cameras. The application was developed using Blender for 3D modeling and Unity as the rendering engine, incorporating the Vuforia SDK for marker-based AR tracking, and it was deployed on the Android operating system. Unlike traditional static approaches, the proposed solution enables learners to explore complex network architectures and key functionalities of 5G in an interactive and accessible manner. To assess its perceived effectiveness, quantitative surveys were conducted with both university and high school students, focusing on usability, engagement, and perceived learning outcomes. Results indicate that the tool is user-friendly, enhances motivation, and supports conceptual understanding as perceived by participants of 5G technologies. These findings highlight the potential of AR, supported by advanced wireless networks, as a pedagogical strategy to improve STEM education and foster technological literacy in the era of digital transformation. Full article
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14 pages, 23202 KB  
Article
Design and Application of a Mobile Ultra-Audio Frequency Electromagnetic Measurement System
by Hongyu Ruan, Zucan Lin, Keyu Zhou, Yongqing Wang, Qisheng Zhang and Hui Zhang
Sensors 2026, 26(7), 2095; https://doi.org/10.3390/s26072095 - 27 Mar 2026
Viewed by 348
Abstract
Although high-frequency electromagnetic methods, such as Radio Magnetotellurics (RMT) and Controlled-Source Radio Magnetotellurics (CSRMT), are highly effective for shallow-to-medium depth exploration, deploying traditional transmitter–receiver setups remains labor-intensive and significantly slows down large-scale surveys. To overcome these logistical bottlenecks, we developed a mobile Ultra-Audio [...] Read more.
Although high-frequency electromagnetic methods, such as Radio Magnetotellurics (RMT) and Controlled-Source Radio Magnetotellurics (CSRMT), are highly effective for shallow-to-medium depth exploration, deploying traditional transmitter–receiver setups remains labor-intensive and significantly slows down large-scale surveys. To overcome these logistical bottlenecks, we developed a mobile Ultra-Audio Frequency Electromagnetic (UAEM) measurement system. While the hardware is designed with dual-mode capabilities supporting conventional controlled-source operations, this paper specifically focuses on its application in a Signals of Opportunity (SOOP) mode. By utilizing pre-existing, stable anthropogenic signals, including Amplitude Modulation (AM) broadcasts and naval very low frequency communications, the system effectively functions as a broadband RMT receiver. Technical evaluations demonstrate that the instrument operates across a 1 Hz to 1000 kHz bandwidth with a high sampling rate of 2.5 MHz. Furthermore, it achieves a dynamic range of 143 dB and maintains an apparent resistivity measurement accuracy of better than 3%. Thanks to its modular, vehicle-towed design, the UAEM system enables continuous, on-the-move data acquisition wherever ambient field sources are available. This approach eliminates the need for dedicated transmitter deployment, fundamentally reducing exploration costs and boosting overall survey efficiency. Full article
(This article belongs to the Special Issue Advanced Sensing Technologies for Space Electromagnetic Environments)
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20 pages, 13040 KB  
Article
SLAM Mobile Mapping for Complex Archaeological Environments: Integrated Above–Below-Ground Surveying
by Gabriele Bitelli, Anna Forte and Emanuele Mandanici
Geomatics 2026, 6(2), 31; https://doi.org/10.3390/geomatics6020031 - 26 Mar 2026
Viewed by 437
Abstract
Archaeological sites characterized by the coexistence of extensive above-ground terrain and hypogeum structures present major challenges for accurate and comprehensive geospatial documentation. Conventional survey approaches—such as static terrestrial laser scanning (TLS), total-station measurements, and aerial photogrammetry—often suffer from operational constraints, particularly in the [...] Read more.
Archaeological sites characterized by the coexistence of extensive above-ground terrain and hypogeum structures present major challenges for accurate and comprehensive geospatial documentation. Conventional survey approaches—such as static terrestrial laser scanning (TLS), total-station measurements, and aerial photogrammetry—often suffer from operational constraints, particularly in the presence of narrow underground spaces, low or absent illumination, harsh environmental conditions, and restrictions on UAV deployment. Additional complexity arises when both surface and subterranean elements must be consistently georeferenced to a common global reference system, especially where establishing a traditional topographic–geodetic control network is impractical. Within the framework of the EIMAWA Egyptian–Italian Mission conducted by the University of Milano since 2018, the Geomatics group of the University of Bologna designed and implemented a multi-scale multi-technique 3D documentation workflow, with a prominent role assumed by Simultaneous Localization and Mapping (SLAM) mobile laser scanning. The approach was supported by GNSS measurements providing centimetric accuracy. SLAM was employed to document both the surface necropolis and multiple hypogeal tombs, enabling rapid acquisition of dense three-dimensional data in environments where traditional techniques are limited. All datasets were integrated within a unified reference system, resulting in a coherent, multi-layered spatial dataset representing both landscape and underground spaces. The results demonstrate that SLAM can produce dense point clouds that document at few-centimetric level accuracy and continuously both above- and below-ground contexts. Quantitative analyses of the co-registration and mutual alignment of multiple SLAM datasets confirm a high degree of internal consistency, further enhanced through post-processing refinement. Overall, the experience indicates that this solution represents a practical and reliable technique for complex archaeological surveying. Full article
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14 pages, 409 KB  
Article
Ultra-Processed Food Consumption and Domain-Specific Quality of Life in Postmenopausal Women: Associations with Mobility and Mental Health
by Byung Soo Kwan, Jung-Hwan Cho, Jun Young Kim, Hye In Kim, Nak Gyeong Ko and Ji Eun Park
Healthcare 2026, 14(6), 791; https://doi.org/10.3390/healthcare14060791 - 20 Mar 2026
Viewed by 298
Abstract
Background/Objectives: Ultra-processed food (UPF) consumption is increasing worldwide, yet its domain-specific impact on health-related quality of life (HRQoL) among postmenopausal women remains poorly characterized. This study investigated associations between UPF intake and domain-specific and overall HRQoL in a nationally representative sample of Korean [...] Read more.
Background/Objectives: Ultra-processed food (UPF) consumption is increasing worldwide, yet its domain-specific impact on health-related quality of life (HRQoL) among postmenopausal women remains poorly characterized. This study investigated associations between UPF intake and domain-specific and overall HRQoL in a nationally representative sample of Korean postmenopausal women. Methods: Data from the Korea National Health and Nutrition Examination Survey (2013–2021) were analyzed. UPF consumption was assessed using a single 24 h dietary recall and classified according to the NOVA food classification system. HRQoL was evaluated using the five EQ-5D domains and the overall EQ-5D index. Survey-weighted logistic regression models estimated odds ratios (ORs) and 95% confidence intervals (CIs) across UPF intake quartiles, adjusting for socioeconomic and health-related covariates. Results: Higher UPF consumption was associated with impairments in specific HRQoL domains rather than a uniform decline across domains. In fully adjusted models, women in the third UPF intake quartile had higher odds of mobility impairment (OR 1.74; 95% CI 1.06–2.86) and anxiety/depression symptoms (OR 1.71; 95% CI 1.06–2.77) than those in the lowest quartile. A significant linear trend was observed for mobility (P-for-trend = 0.012). In contrast, associations with the overall EQ-5D index score were limited and not consistently observed after full adjustment. Conclusions: Higher UPF consumption is associated with domain-specific HRQoL impairments, particularly affecting physical mobility and mental health, among postmenopausal women. These findings underscore the importance of domain-specific assessments and suggest that UPF consumption may be related to certain aspects of functional and psychological well-being after menopause. Full article
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23 pages, 574 KB  
Article
Aberrant Driver Behavior, Poor Sleep, Fatigue Among Bus Rapid Transit Drivers and Sustainable Traffic Safety
by Jaime Santos-Reyes
Sustainability 2026, 18(5), 2384; https://doi.org/10.3390/su18052384 - 1 Mar 2026
Viewed by 332
Abstract
A great deal of effort has been made to investigate and develop approaches to address driver behavior, fatigue, and sleepiness for different road users worldwide. However, very little research has been conducted to explore these issues in the context of Bus Rapid Transit [...] Read more.
A great deal of effort has been made to investigate and develop approaches to address driver behavior, fatigue, and sleepiness for different road users worldwide. However, very little research has been conducted to explore these issues in the context of Bus Rapid Transit (BRT) drivers in a low-income countries such as Mexico. The present study fills this gap. The aim of this study is to identify the human factors contributing to aberrant driver behavior (ADB) among BRT professional drivers in Mexico City. A total of 152 drivers participated in a self-reported survey. Exploratory factor analysis was performed on the BRT-ADBQ to identify the behavioral factors, and the Checklist Individual Strength (CIS–Fatigue) subscale was employed to assess the fatigue of drivers. The key findings were the following: (a) the created BRT-ABDQ identified two ADBs (violations and errors); (b) violations factors, but not errors, contributed to accident involvement; (c) ADB, fatigue, poor sleep and age (30–39) were predictors to accidents and (d) a linear trend has been revealed indicating that as the hours of sleep decreased, the experience of fatigue increased proportionally. The conclusion of the study is that ADB, sleepiness, and fatigue are real and existent among BRT drivers and should be a matter of concern for the case of the BRT organization that participated in the study. More generally, organizations running these systems should intervene by implementing sleep and fatigue reduction strategies to mitigate the adverse impact of these and thereby contribute to sustainable traffic safety and urban mobility. Full article
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33 pages, 3858 KB  
Systematic Review
Quadruped Robots in Construction Automation: A Comprehensive Review of Applications, Localization, and Site-Level Operations
by Azizbek Kakhkharov, Jong-Wook Kim and Jae-ho Choi
Buildings 2026, 16(5), 962; https://doi.org/10.3390/buildings16050962 - 1 Mar 2026
Cited by 1 | Viewed by 1420
Abstract
This paper presents a comprehensive review of quadruped robots in the construction industry, focusing on their applications, technological capabilities, and integration with digital construction workflows. Quadruped robots have emerged as promising mobile platforms due to their ability to traverse uneven terrain, operate autonomously, [...] Read more.
This paper presents a comprehensive review of quadruped robots in the construction industry, focusing on their applications, technological capabilities, and integration with digital construction workflows. Quadruped robots have emerged as promising mobile platforms due to their ability to traverse uneven terrain, operate autonomously, and support multimodal sensing, enabling tasks such as site inspection, 3D reality capture, safety monitoring, logistics support, and integration with Building Information Modeling (BIM) and digital-twin systems. Despite these advantages, real-world deployment remains constrained by limitations in battery endurance, payload capacity, communication reliability, perception robustness, and system interoperability. This review synthesizes findings from 20 studies published between 2015 and 2025 and incorporates a quantitative bibliometric analysis using both SciVal and Scopus. While SciVal provides performance-based indicators and global research trends, Scopus offers complementary publication coverage, improving analytical reliability. Unlike general robotics surveys, this review adopts a construction-centric perspective by explicitly linking quadruped robot capabilities to construction engineering objectives under practical site conditions. The findings highlight current application domains, technological gaps, and adoption barriers, and outline future research directions to support the effective integration of quadruped robots into construction practice. This review provides actionable insights for researchers, engineers, and practitioners assessing the readiness and limitations of quadruped robots in construction environments. Full article
(This article belongs to the Special Issue Robotics, Automation and Digitization in Construction)
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38 pages, 6725 KB  
Article
A BIM-Based Digital Twin Framework for Urban Roads: Integrating MMS and Municipal Geospatial Data for AI-Ready Urban Infrastructure Management
by Vittorio Scolamiero and Piero Boccardo
Sensors 2026, 26(3), 947; https://doi.org/10.3390/s26030947 - 2 Feb 2026
Viewed by 930
Abstract
Digital twins (DTs) are increasingly adopted to enhance the monitoring, management, and planning of urban infrastructure. While DT development for buildings is well established, applications to urban road networks remain limited, particularly in integrating heterogeneous geospatial datasets into semantically rich, multi-scale representations. This [...] Read more.
Digital twins (DTs) are increasingly adopted to enhance the monitoring, management, and planning of urban infrastructure. While DT development for buildings is well established, applications to urban road networks remain limited, particularly in integrating heterogeneous geospatial datasets into semantically rich, multi-scale representations. This study presents a methodology for developing a BIM-based DT of urban roads by integrating geospatial data from Mobile Mapping System (MMS) surveys with semantic information from municipal geodatabases. The approach follows a multi-modal (point clouds, imagery, vector data), multi-scale and multi-level framework, where ‘multi-level’ refers to modeling at different scopes—from a city-wide level, offering a generalized representation of the entire road network, to asset-level detail, capturing parametric BIM elements for individual road segments or specific components such as road sign and road marker, lamp posts and traffic light. MMS-derived LiDAR point clouds allow accurate 3D reconstruction of road surfaces, curbs, and ancillary infrastructure, while municipal geodatabases enrich the model with thematic layers including pavement condition, road classification, and street furniture. The resulting DT framework supports multi-scale visualization, asset management, and predictive maintenance. By combining geometric precision with semantic richness, the proposed methodology delivers an interoperable and scalable framework for sustainable urban road management, providing a foundation for AI-ready applications such as automated defect detection, traffic simulation, and predictive maintenance planning. The resulting DT achieved a geometric accuracy of ±3 cm and integrated more than 45 km of urban road network, enabling multi-scale analyses and AI-ready data fusion. Full article
(This article belongs to the Special Issue Intelligent Sensors and Artificial Intelligence in Building)
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30 pages, 11051 KB  
Article
Investigating the Impact of Education 4.0 and Digital Learning on Students’ Learning Outcomes in Engineering: A Four-Year Multiple-Case Study
by Jonathan Álvarez Ariza and Carola Hernández Hernández
Informatics 2026, 13(2), 18; https://doi.org/10.3390/informatics13020018 - 23 Jan 2026
Cited by 1 | Viewed by 1675
Abstract
Education 4.0 and digital learning have led to a technology-driven transformation in educational methodologies and the roles of teachers, primarily at Higher Education Institutions (HEIs). From an educational standpoint, the extant literature on Education 4.0 highlights its technological features and benefits; however, there [...] Read more.
Education 4.0 and digital learning have led to a technology-driven transformation in educational methodologies and the roles of teachers, primarily at Higher Education Institutions (HEIs). From an educational standpoint, the extant literature on Education 4.0 highlights its technological features and benefits; however, there is a lack of studies that assess its impact on students’ learning outcomes. Seemingly, Education 4.0 features are taken for granted, as if the technology in itself were enough to guarantee students’ learning, self-efficacy, and engagement. Seeking to address this lack, this study describes the implications of tailoring Education 4.0 tenets and digital learning in an engineering curriculum. Four case studies conducted in the last four years with 119 students are presented, in which technologies such as digital twins, a Modular Production System (MPS), low-cost robotics, 3D printing, generative AI, machine learning, and mobile learning were integrated. With these case studies, an educational methodology with active learning, hands-on activities, and continuous teacher support was designed and deployed to foster cognitive and affective learning outcomes. A mixed-methods study was conducted, utilizing students’ grades, surveys, and semi-structured interviews to assess the approach’s impact. The outcomes suggest that including Education 4.0 tenets and digital learning can enhance discipline-based skills, creativity, self-efficacy, collaboration, and self-directed learning. These results were obtained not only via the technological features but also through the incorporation of reflective teaching that provided several educational resources and oriented the methodology for students’ learning and engagement. The results of this study can help complement the concept of Education 4.0, helping to find a student-centered approach and conceiving a balance between technology, teaching practices, and cognitive and affective learning outcomes. Full article
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35 pages, 22348 KB  
Article
Performance Assessment of Portable SLAM-Based Systems for 3D Documentation of Historic Built Heritage
by Valentina Bonora and Martina Colapietro
Sensors 2026, 26(2), 657; https://doi.org/10.3390/s26020657 - 18 Jan 2026
Cited by 1 | Viewed by 728
Abstract
The rapid and reliable geometric documentation of historic built heritage is a key requirement for a wide range of conservation, analysis, and risk assessment activities. In recent years, portable and wearable Simultaneous Localization and Mapping (SLAM)-based systems have emerged as efficient tools for [...] Read more.
The rapid and reliable geometric documentation of historic built heritage is a key requirement for a wide range of conservation, analysis, and risk assessment activities. In recent years, portable and wearable Simultaneous Localization and Mapping (SLAM)-based systems have emerged as efficient tools for fast 3D data acquisition, offering significant advantages in terms of operational speed, accessibility, and flexibility. This paper presents an experimental performance assessment of three portable SLAM-based mobile mapping systems applied to the 3D documentation of historic religious buildings. Two historic parish churches in the Lunigiana region (Italy) are used as case studies to evaluate the systems under real-world conditions. The analysis focuses on key performance indicators relevant to metric documentation, including georeferencing accuracy, 3D model accuracy, point cloud density and resolution, and model completeness. The results highlight the capabilities and limitations of the tested systems, showing that all instruments can efficiently capture the primary geometries of complex historic buildings, while differences emerge in terms of accuracy, data consistency, and readability of architectural details. Although the work is framed within a broader research project addressing seismic vulnerability of historic structures, this contribution specifically focuses on the experimental evaluation of SLAM-based surveying performance. The results demonstrate that portable SLAM systems provide reliable geometric datasets suitable for preliminary documentation tasks and for supporting further multidisciplinary analyses, representing a valuable resource for the rapid 3D documentation of historic built heritage. Full article
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24 pages, 39327 KB  
Article
Forest Surveying with Robotics and AI: SLAM-Based Mapping, Terrain-Aware Navigation, and Tree Parameter Estimation
by Lorenzo Scalera, Eleonora Maset, Diego Tiozzo Fasiolo, Khalid Bourr, Simone Cottiga, Andrea De Lorenzo, Giovanni Carabin, Giorgio Alberti, Alessandro Gasparetto, Fabrizio Mazzetto and Stefano Seriani
Machines 2026, 14(1), 99; https://doi.org/10.3390/machines14010099 - 14 Jan 2026
Viewed by 905
Abstract
Forest surveying and inspection face significant challenges due to unstructured environments, variable terrain conditions, and the high costs of manual data collection. Although mobile robotics and artificial intelligence offer promising solutions, reliable autonomous navigation in forest, terrain-aware path planning, and tree parameter estimation [...] Read more.
Forest surveying and inspection face significant challenges due to unstructured environments, variable terrain conditions, and the high costs of manual data collection. Although mobile robotics and artificial intelligence offer promising solutions, reliable autonomous navigation in forest, terrain-aware path planning, and tree parameter estimation remain open challenges. In this paper, we present the results of the AI4FOREST project, which addresses these issues through three main contributions. First, we develop an autonomous mobile robot, integrating SLAM-based navigation, 3D point cloud reconstruction, and a vision-based deep learning architecture to enable tree detection and diameter estimation. This system demonstrates the feasibility of generating a digital twin of forest while operating autonomously. Second, to overcome the limitations of classical navigation approaches in heterogeneous natural terrains, we introduce a machine learning-based surrogate model of wheel–soil interaction, trained on a large synthetic dataset derived from classical terramechanics. Compared to purely geometric planners, the proposed model enables realistic dynamics simulation and improves navigation robustness by accounting for terrain–vehicle interactions. Finally, we investigate the impact of point cloud density on the accuracy of forest parameter estimation, identifying the minimum sampling requirements needed to extract tree diameters and heights. This analysis provides support to balance sensor performance, robot speed, and operational costs. Overall, the AI4FOREST project advances the state of the art in autonomous forest monitoring by jointly addressing SLAM-based mapping, terrain-aware navigation, and tree parameter estimation. Full article
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23 pages, 52765 KB  
Article
GNSS NRTK, UAS-Based SfM Photogrammetry, TLS and HMLS Data for a 3D Survey of Sand Dunes in the Area of Caleri (Po River Delta, Italy)
by Massimo Fabris and Michele Monego
Land 2026, 15(1), 95; https://doi.org/10.3390/land15010095 - 3 Jan 2026
Viewed by 485
Abstract
Coastal environments are fragile ecosystems threatened by various factors, both natural and anthropogenic. The preservation and protection of these environments, and in particular, the sand dune systems, which contribute significantly to the defense of the inland from flooding, require continuous monitoring. To this [...] Read more.
Coastal environments are fragile ecosystems threatened by various factors, both natural and anthropogenic. The preservation and protection of these environments, and in particular, the sand dune systems, which contribute significantly to the defense of the inland from flooding, require continuous monitoring. To this end, high-resolution and high-precision multitemporal data acquired with various techniques can be used, such as, among other things, the global navigation satellite system (GNSS) using the network real-time kinematic (NRTK) approach to acquire 3D points, UAS-based structure-from-motion photogrammetry (SfM), terrestrial laser scanning (TLS), and handheld mobile laser scanning (HMLS)-based light detection and ranging (LiDAR). These techniques were used in this work for the 3D survey of a portion of vegetated sand dunes in the Caleri area (Po River Delta, northern Italy) to assess their applicability in complex environments such as coastal vegetated dune systems. Aerial-based and ground-based acquisitions allowed us to produce point clouds, georeferenced using common ground control points (GCPs), measured both with the GNSS NRTK method and the total station technique. The 3D data were compared to each other to evaluate the accuracy and performance of the different techniques. The results provided good agreement between the different point clouds, as the standard deviations of the differences were lower than 9.3 cm. The GNSS NRTK technique, used with the kinematic approach, allowed for the acquisition of the bare-ground surface but at a cost of lower resolution. On the other hand, the HMLS represented the poorest ability in the penetration of vegetation, providing 3D points with the highest elevation value. UAS-based and TLS-based point clouds provided similar average values, with significant differences only in dense vegetation caused by a very different platform of acquisition and point of view. Full article
(This article belongs to the Special Issue Digital Earth and Remote Sensing for Land Management, 2nd Edition)
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34 pages, 7143 KB  
Review
Knowledge Distillation in Object Detection: A Survey from CNN to Transformer
by Tahira Shehzadi, Rabya Noor, Ifza Ifza, Marcus Liwicki, Didier Stricker and Muhammad Zeshan Afzal
Sensors 2026, 26(1), 292; https://doi.org/10.3390/s26010292 - 2 Jan 2026
Viewed by 1421
Abstract
Deep learning models, especially for object detection have gained immense popularity in computer vision. These models have demonstrated remarkable accuracy and performance, driving advancements across various applications. However, the high computational complexity and large storage requirements of state-of-the-art object detection models pose significant [...] Read more.
Deep learning models, especially for object detection have gained immense popularity in computer vision. These models have demonstrated remarkable accuracy and performance, driving advancements across various applications. However, the high computational complexity and large storage requirements of state-of-the-art object detection models pose significant challenges for deployment on resource-constrained devices like mobile phones and embedded systems. Knowledge Distillation (KD) has emerged as a prominent solution to these challenges, effectively compressing large, complex teacher models into smaller, efficient student models. This technique maintains good accuracy while significantly reducing model size and computational demands, making object detection models more practical for real-world applications. This survey provides a comprehensive review of KD-based object detection models developed in recent years. It offers an in-depth analysis of existing techniques, highlighting their novelty and limitations, and explores future research directions. The survey covers the different distillation algorithms used in object detection. It also examines extended applications of knowledge distillation in object detection, such as improvements for lightweight models, addressing catastrophic forgetting in incremental learning, and enhancing small object detection. Furthermore, the survey also delves into the application of knowledge distillation in other domains such as image classification, semantic segmentation, 3D reconstruction, and document analysis. Full article
(This article belongs to the Section Sensing and Imaging)
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