Search Results (769)

Monitoring steep slopes in mountainous canyon areas has always been a challenging problem, especially during the construction of large hydropower projects. Effective monitoring is crucial for construction safety and operational security. However, under complex terrain conditions, existing monitoring methods have significant limitations and cannot comprehensively and accurately cover steep slopes. To address the above challenges, this study proposes a multi-temporal UAV-based photogrammetric offset tracking (POT) monitoring method assisted by terrestrial laser scanning (TLS), which is primarily applicable to rocky and texture-rich steep slopes. This method utilizes TLS point cloud data to provide supplementary ground control points (TLS-GCPs) for UAV image modeling, effectively overcoming the difficulty of deploying conventional RTK ground control points (RTK-GCPs) on high and steep slopes, thereby significantly improving the accuracy of UAV-based Structure-from-Motion (SfM) models. In a case study at a hydropower station, we employed TLS-assisted UAV modeling to produce high-precision UAV images. Using POT technology, we successfully identified signs of slope deformation between January 2024 and December 2024. Comparative experiments with traditional algorithms demonstrated that in areas where RTK-GCPs cannot be deployed, this method greatly enhances UAV modeling accuracy, fully meeting the monitoring requirements for steep slopes in complex terrains. Full article

The article addresses the issue of panoramic photogrammetry for the reconstruction of interior spaces. Such environments often present challenges, including poor lighting conditions and surfaces with variable texture for photogrammetric scanning. In this case study, we reconstruct the interior spaces of the historical house of Samuel Mikovíni, which represents these unfavorable conditions. The 3D reconstruction of interior spaces is performed using the Ricoh Theta Z1 spherical camera (Ricoh Company, Ltd.; Tokyo, Japan) in six variants, each employing a different number of images and different camera networks. Scale is introduced into the reconstructions based on significant dimensions measured with a measuring tape. A comparison is carried out using a point cloud obtained from terrestrial laser scanning and difference point clouds are generated for each variant. Based on the results, reconstructions produced from a reduced number of spherical images can serve as a basic source for simple documentation with accuracy up to 0.15 m. When the number of spherical images is increased and images from different height levels are included, the reconstruction accuracy improves markedly, achieving positional accuracy of up to 0.05 m, even in areas affected by poor lighting conditions or low-texture surfaces. The results confirm that for interior reconstruction, a higher number of images not only increases the density of the reconstructed point cloud but also enhances its positional accuracy. Full article

Traditional villages stand as irreplaceable treasures of global cultural heritage, embodying profound historical, cultural, and esthetic values. However, the accelerating pace of urbanization has exposed them to unprecedented threats, including structural degradation, loss of intangible cultural practices, and the homogenization of rural landscapes. In recent years, three-dimensional (3D) laser scanning, unmanned aerial vehicles (UAVs), and other advanced geospatial technologies have been increasingly applied in the conservation and restoration of architectural heritage. The digital documentation of traditional dwellings not only ensures the accuracy and efficiency of conservation efforts but also minimizes physical intervention, thereby safeguarding the authenticity and integrity of heritage sites. This study examines the architectural characteristics and conservation challenges of traditional Huizhou dwellings in Huangshan City, Anhui Province, by integrating oblique photogrammetry, terrestrial laser scanning (TLS), and 3D modeling. Close-range photogrammetry, combined with image matching algorithms and computer vision techniques, was used to produce highly detailed 3D models of historical structures. UAV-based data acquisition was further employed to generate Heritage Building Information Modeling (HBIM) from point cloud datasets, which were subsequently pre-processed and denoised for restoration simulations. In addition, HBIM was utilized to conduct quantitative analyses of architectural components, providing critical support for heritage management and decision-making in conservation planning. The findings demonstrate that 3D digitization offers a sustainable and replicable model for the protection, revitalization, and adaptive reuse of traditional villages, contributing to the long-term preservation of their cultural and architectural legacy. Full article

The Macao rammed earth wall is a typical representative of cultural heritage in hot-humid regions. However, the spatial differentiation mechanisms of its surface deterioration remain unclear. This study, taking the Old Wall in Macao as a case, combined field investigation with terrestrial laser scanning (TLS) and thermal imaging to systematically reveal the spatial distribution patterns of surface pathologies and their hydrological driving mechanisms. Based on structural separations and deterioration characteristics, the wall was divided into three adjacent sections for comparative analysis. The main conclusions are as follows: (1) Quantitative analysis showed the section with a gentler slope (77%) experienced significant flatness deterioration due to uneven settlement, promoting internal water penetration that triggered severe undercutting (35% of its surface area); (2) The other two sections maintained steep slopes (86%) that promoted surface runoff, which combined with adjacent building drainage led to significant biological colonization (68% in the section most affected by nearby temple drainage); (3) Thermal imaging verified the correlation between water infiltration cores and temperature-flatness anomalies, enabling construction of a coupled “geometry-hydrology-pathology” model that elucidates the complete causal chain from foundation settlement to surface pathology. This study provides a theoretical basis and technical support for the differentiated protection of rammed earth heritage in hot-humid environments. Full article

The study aims to reconstruct the life history of an individual whose skeleton was recovered during the excavation of the late medieval Pauline monastery of the Blessed Virgin Mary on Moslavina Mountain, Croatia. The monastery was one of the most important ecclesiastical centres in continental Croatia during the 14th/15th centuries CE and was abandoned between 1520 and 1544 due to fear of imminent Ottoman attacks. The inscription and coat of arms on the tombstone of a tomb located in the chancel, next to the main altar, indicate that the skeleton belongs to Sofia Kaštelančić née di Prata (di Pordenone), a member of Croatian late medieval high-ranking nobility. We conducted a conventional bioarchaeological study, carbon and nitrogen stable isotopes analysis, paleoradiological imaging (CT/CBCT scanning), and three-dimensional facial reconstruction. The skeleton belongs to a middle-aged woman between 40 and 50 years old with an estimated stature of about 161 cm. Numerous pathological changes, such as ante mortem tooth loss, caries, abscess, linear enamel hypoplasia, dysodontiasis, and osteophytosis were observed, with the most notable pathology being the fracture of the right ankle, a fact also confirmed by CT scanning. Carbon and nitrogen isotopic values are consistent with a terrestrial diet based on C₃ plants with no marine input, and the consumption of large quantities of animal-based proteins. Three-dimensional facial reconstruction made it possible for the first time in over 500 years to obtain the approximate physical appearance of the individual. The presented results are consistent with the hypothesis that the skeleton probably belongs to Sofia Kaštelančić. Nevertheless, none of the observed osteological traits are individually or collectively diagnostic of Sofia, so, in the absence of individualising evidence, the identification remains hypothetical rather than demonstrative. Full article

This study introduces a novel, automated image-to-BIM (Building Information Modeling) workflow designed to generate semantically rich and geometrically useful BIM models directly from RGB images. Conventional scan-to-BIM often relies on specialized, costly, and time-intensive equipment, specifically if LiDAR is used to generate point clouds (PCs). Typical workflows are followed by a separate post-processing step for semantic segmentation recently performed by deep learning models on the generated PCs. Instead, the proposed method integrates vision language object detection (YOLOv8x-World v2) and vision based segmentation (SAM 2.1) with Neural Radiance Fields (NeRF) 3D reconstruction to generate segmented, color-labeled PCs directly from images. The key novelty lies in bypassing post-processing on PCs by embedding semantic information at the pixel level in images, preserving it through reconstruction, and encoding it into the resulting color labeled PC, which allows building elements to be directly identified and geometrically extracted based on color labels. Extracted geometry is serialized into a JSON format and imported into Revit to automate BIM creation for walls, windows, and doors. Experimental validation on BIM models generated from Unmanned Aerial Vehicle (UAV)-based exterior datasets and standard camera-based interior datasets demonstrated high accuracy in detecting windows and doors. Spatial evaluations yielded up to 0.994 precision and 0.992 Intersection over Union (IoU). NeRF and Gaussian Splatting models, Nerfacto, Instant-NGP, and Splatfacto, were assessed. Nerfacto produced the most structured PCs suitable for geometry extraction and Splatfacto achieved the highest image reconstruction quality. The proposed method removes dependency on terrestrial surveying tools and separate segmentation processes on PCs. It provides a low-cost and scalable solution for generating BIM models in aging or undocumented buildings and supports practical applications such as renovation, digital twin, and facility management. Full article

Terrestrial laser scanning (TLS) point clouds require high-precision registration and georeferencing to be used effectively. Only then can data from multiple stations be integrated and transformed from the instrument’s local coordinate system into a common, stable reference frame that ensures temporal consistency for further analyses of displacement and deformation. The article demonstrates the validation of an innovative referencing system devised to improve the reliability and accuracy of registering and georeferencing TLS point clouds. The primary component of the system is openable reference spheres, whose centroids can be directly and precisely determined using surveying methods. It also includes dedicated adapters: tripods and adjustable F-clamps with which the spheres can be securely mounted on various structural components, facilitating the optimal distribution of the reference markers. Laboratory tests with four modern laser scanners (Z+F Imager 5010C, Riegl VZ-400, Leica ScanStation P40, and Trimble TX8) revealed sub-millimetre accuracy of sphere fit and form errors, along with the sphere distance error within the acceptance threshold. This confirms that there are no significant systematic errors and that the system is fully compatible with various TLS technologies. The registration and georeferencing quality parameters demonstrate the system’s stability and repeatability. They were additionally verified with independent control points and geodetic levelling of the centres of the spheres. The system overcomes the critical limitations of traditional reference spheres because their centres can be measured directly using surveying methods. This facilitates registration and georeferencing accuracy on par with, or even better than, that of commercial targets. The proposed system serves as a stable and repeatable reference frame suitable for high-precision engineering applications, deformation monitoring, and longitudinal analyses. Full article

The technical challenge of balancing radiant illuminance and the angular diameter of the simulated sun remains unsolved, preventing the realization of a solar simulator with both a 32′ angular diameter and a solar constant irradiance. This paper proposes a direct solar radiation simulation method using grating anomalous dispersion and a technological implementation scheme. This new architecture consists of a spectrally modulated optical engine, a diffractive combining system, and a multi-aperture imaging reconstruction system. We designed an optical system for simulating direct solar radiation, which achieves a high degree of reproducibility of natural direct solar radiation characteristics. The performance of this system was verified through simulation, with the results indicating that the solar direct radiation simulator achieves an angular diameter of 31.7′ while maintaining radiant illuminance above a solar constant. Additionally, the system spectral match to both the extraterrestrial (AM0G) and terrestrial global (AM1.5G) solar spectra, along with its uniformity, complies with an A+ grade. The studied direct solar radiation simulation is currently the only instrument capable of achieving a solar constant of an angular diameter less than 32′. This research revolutionizes the structure and principle of the traditional solar simulator, makes up for the deficiencies of the existing solar simulation technology, further improves the theoretical system of solar direct radiation simulation, and has far-reaching scientific significance for the development and application of solar simulation technology. Full article

This paper addresses the degradation of imaging quality in high-resolution CubeSats caused by micro-vibrations from attitude control flywheels. It proposes a micro-vibration suppression scheme that incorporates multi-disciplinary integrated modeling, dual passive vibration isolation, and multi-level verification. A comprehensive model encompassing flywheel disturbance, optics, attitude control, and structure is developed to elucidate the transmission dynamics of micro-vibrations from the source to the optical payload. A dual suppression system utilizing silicone rubber isolators is engineered for both the disturbance source (flywheel) and the payload (optical camera). By optimizing stiffness matching and damping, it achieves a balance between isolation efficiency and stability in attitude control. A three-tier verification system comprising “numerical simulation–ground microgravity testing–on-orbit imaging” has been established. The findings indicate that the dual isolation system diminishes the pixel offset amplitude of the optical payload to under 0.1 pixels (down to the 0.02 pixel level in the high-frequency band), with an isolation efficiency of 80%. Consistent outcomes from terrestrial and orbital validation affirm the engineering viability of the plan. This research offers theoretical backing for the precise control of micro-vibrations in micro-nano satellites, thereby enhancing their utility in high-resolution remote sensing applications. Full article

The three-dimensional documentation of hypogean structures poses significant methodological challenges due to the absence of natural light, confined spaces, and the presence of fragile painted surfaces. This study presents an integrated workflow for the survey of the Tomba dell’Orco (Tarquinia), combining terrestrial laser scanning, photogrammetry, and the light painting technique. Borrowed from photographic practice, light painting was employed as a dynamic lighting strategy during photogrammetric acquisition to overcome issues of uneven illumination and harsh shadows typical of underground environments. By moving handheld LED sources throughout long-exposure shots, operators produced evenly illuminated images suitable for feature extraction and high-resolution texture generation. These image datasets were subsequently integrated with laser scanning point clouds through a structured pipeline encompassing registration, optimization, and texture reprojection, culminating in web dissemination via the ATON framework. The methodological focus demonstrates that light painting provides a scalable and replicable solution for documenting complex hypogean contexts, improving the photometric quality and surface readability of 3D models while reducing acquisition time compared to static lighting setups. The results highlight the potential of dynamic illumination as an operational enhancement for 3D recording workflows in low-light cultural heritage environments. Full article

Accurate inspection of retaining walls is crucial for ensuring structural integrity and public safety. Current assessment methods rely predominantly on qualitative visual evaluations that inform numerical structural ratings. These ratings lack the comprehensive quantitative measurements that 3D imaging can provide. This study evaluates the feasibility and accuracy of drone-based lidar platforms for retaining wall inspection as an alternative to traditional terrestrial laser scanning (TLS) that improves accessibility on hard-to-reach sites and may increase efficiency on site due to preplanned flights. Data was collected from three representative walls exhibiting diverse conditions using TLS and drone-lidar. To provide additional information on the site to use for alignment and checks, both Global Navigation Satellite System (GNSS) control and total stations were employed. The study provides a comparative analysis of the accuracy and practicality of each lidar method, aiming to determine the most effective techniques for routine inspection applications given varying site conditions. When compared against a finely registered TLS ground truth, drone-lidar was found to have root mean square errors of 2.3 cm in areas with low vegetation and 24.2 cm in densely vegetated areas. The findings highlight potential improvements in the precision of retaining wall assessments, proposing a shift from current qualitative practices to reliable, data-driven evaluations. Key limitations in GNSS accuracy and sites with dense vegetation are discussed. Full article

Measurement systems such as laser trackers and 3D imaging systems are being increasingly adopted across the manufacturing industry. These metrology technologies can allow for live, high-precision measurement in a digital system, enabling the spatial component of the digital manufacturing twin. In aircraft wing manufacturing, drilling and fastening operations must be guided by precise measurements from a digital design model. With thousands of fasteners on each aircraft wing, even small errors in alignment of surface covers to wing ribs and spars can impact component longevity due to aerodynamic drag. Determining surface conformance of airstream-facing surfaces is currently largely performed though manual gauge checking by human operators. In order to capture the surface details and reverse engineer components to assure tolerance has been achieved, laser scanners could be utilised alongside a precise registration strategy. This work explores the quality of the aerostructure surface in a captured point cloud and the subsequent accuracy of surface normal determination from planar fastener heads. These point clouds were captured with a reference hand-held laser scanner and two terrestrial laser scanners. This study assesses whether terrestrial laser scanners can achieve <0.5° surface normal accuracy for aerospace fastener alignment. Accuracy of the surface normals was achieved with a nominal mean discrepancy of 0.42 degrees with the Leica RTC360 3D Laser Scanner (Leica Geosystems AG, Heerbrugg, Switzerland) and 0.27 degrees with the Surphaser 80HSX Ultra Short Range (Basis Software Inc., Redmond, WA, USA). Full article

As a vital carbon reservoir in terrestrial ecosystems, forest canopy height plays a pivotal role in determining the precision of biomass estimation and carbon storage calculations. Acquiring an accurate Canopy Height Map (CHM) is crucial for building carbon budget models at regional and global scales. A novel UNet++ deep-learning model was constructed using Sentinel-1 and Sentinel-2 multispectral remote sensing images to estimate forest canopy height data based on full-waveform LiDAR measurements from the Global Ecosystem Dynamics Investigation (GEDI) satellite. A 10 m resolution CHM was generated for Chaling County, China. The model was evaluated using independent validation samples, achieving an R² of 0.58 and a Root Mean Square Error (RMSE) of 3.38 m. The relationships between multiple Relative Height (RH) metrics and field validation data are examined. It was found that RH98 showed the strongest correlation, with an R² of 0.56 and RMSE of 5.83 m. Six different preprocessing algorithms for GEDI data were evaluated, and the results demonstrated that RH98 processed using the ‘a1’ algorithm achieved the best agreement with the validation data, yielding an R² of 0.55 and RMSE of 5.54 m. The impacts of vegetation coverage, assessed through Normalized Difference Vegetation Index (NDVI), and terrain slope on inversion accuracy are explored. The highest accuracy was observed in areas where NDVI ranged from 0.25 to 0.50 (R² = 0.77, RMSE = 2.27 m) and in regions with slopes between 0° and 10° (R² = 0.61, RMSE = 2.99 m). These results highlight that the selection of GEDI data preprocessing methods, RH metrics, vegetation density, and terrain characteristics (slope) all have significant impacts on the accuracy of canopy height estimation. Full article

Achieving carbon neutrality requires a comprehensive understanding of terrestrial carbon dynamics, particularly the capacity of ecosystems to act as carbon sinks. This study quantified the temporal and spatial variability of net primary production (NPP) and net ecosystem production (NEP) across South Korea from 2010 to 2024, assessing long-term carbon sink trends and their implications for carbon neutrality and nature-based solutions (NbSs). Using the Carnegie–Ames–Stanford Approach (CASA) model driven by Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data and climate variables, we estimated ecosystem carbon fluxes at high spatial and temporal resolutions. In 2024, national NPP totaled 78.63 Mt CO₂ yr⁻¹, with a mean value of 1956.63 t CO₂ ha⁻¹ yr⁻¹. High productivity was concentrated in upland forests of Gangwon-do, Mt. Jirisan, and northern Gyeongsangbuk-do, where favorable vegetation indices and climatic conditions enhanced photosynthesis. Lower productivity occurred in urbanized areas and intensively farmed lowlands. Heterotrophic respiration (RH) was estimated at 15.35 Mt CO₂ yr⁻¹, with elevated rates in warm, humid lowlands and reduced values in high-elevation forests. The resulting NEP in 2024 was 63.29 Mt CO₂ yr⁻¹, with strong sinks along the Baekdudaegan Range and localized negative NEP pockets in lowlands dominated by urban development or agriculture. From 2010 to 2024, the spatially averaged NPP increased from 1170 to 1543 g C m⁻² yr⁻¹, indicating a general upward trend in ecosystem productivity. However, interannual variability was influenced by climatic fluctuations, land-cover changes, and data masking adjustments. These findings provide critical insights into the spatiotemporal dynamics of terrestrial carbon sinks in South Korea, offering essential baseline data for national greenhouse gas inventories and the strategic integration of NbSs into carbon-neutral policies. Full article

The detection and characterization of exoplanets are central topics in astronomy, and high-contrast imaging techniques such nulling interferometry, coronagraphs, and extreme adaptive optics (ExAO) are key tools for the direct detection of exoplanets. This review synthesizes the pivotal role of these techniques in astronomical research and critically analyzes their role as key drivers of progress in the field. Nulling interferometry suppresses stellar light through the phase control of multiple telescopes, thereby enhancing the detection of faint planetary signals. This technology has evolved from the initial Bracewell concept to the LIFE (Large Interferometer For Exoplanets) technique, which will achieve a contrast ratio of 10⁻⁷ in the mid-infrared wavelength range in the future. Coronagraphs block starlight to create a “dark region” for direct observation of exoplanets. By leveraging innovative mask designs, theoretical contrast ratios of up to 4 × 10⁻⁹ can be achieved. ExAO systems achieve precise wavefront correction to optimize the high-contrast imaging performance and mitigate atmospheric disturbances. By leveraging wavefront sensing, thousand-element deformable mirrors, and real-time control algorithms, these systems suppress the turbulence correction residuals to 80 nm RMS, enabling ground-based telescopes to achieve a Strehl ratio exceeding 0.9. This work provides a comprehensive analysis of the underlying principles, prevailing challenges, and future application prospects of these technologies in astronomy. Full article