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Displacement Study of a Large-Scale Freeform Timber Plate Structure Using a Total Station and a Terrestrial Laser Scanner
摘要： Recent advances in timber construction have led to the realization of complex timber plate structures assembled with wood-wood connections. Although advanced numerical modelling tools have been developed to perform their structural analysis, limited experimental tests have been carried out on large-scale structures. However, experimental investigations remain necessary to better understand their mechanical behaviour and assess the numerical models developed. In this paper, static loading tests performed on timber plate shells of about 25 m span are reported. Displacements were measured at 16 target positions on the structure using a total station and on its entire bottom surface using a terrestrial laser scanner. Both methods were compared to each other and to a finite element model in which the semi-rigidity of the connections was represented by springs. Total station measurements provided more consistent results than point clouds, which nonetheless allowed the visualization of displacement fields. Results predicted by the model were found to be in good agreement with the measurements compared to a rigid model. The semi-rigid behaviour of the connections was therefore proven to be crucial to precisely predict the behaviour of the structure. Furthermore, large variations were observed between as-built and designed geometries due to the accumulation of fabrication and construction tolerances.
关键词： terrestrial laser scanning,total station,finite element spring model,point cloud registration,timber plate structures
更新于2025-09-19 17:13:59
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Microscopy and Analysis || Automatic Interpretation of Melanocytic Images in Confocal Laser Scanning Microscopy
摘要： The frequency of melanoma doubles every 20 years. The early detection of malignant changes augments the therapy success. Confocal laser scanning microscopy (CLSM) enables the noninvasive examination of skin tissue. To diminish the need for training and to improve diagnostic accuracy, computer-aided diagnostic systems are required. Two approaches are presented: a multiresolution analysis and an approach based on deep layer convolutional neural networks. For the diagnosis of the CLSM views, architectural structures such as micro-anatomic structures and cell nests are used as guidelines by the dermatologists. Features based on the wavelet transform enable an exploration of architectural structures at different spatial scales. The subjective diagnostic criteria are objectively reproduced. A tree-based machine-learning algorithm captures the decision structure explicitly and the decision steps are used as diagnostic rules. Deep layer neural networks require no a priori domain knowledge. They are capable of learning their own discriminatory features through the direct analysis of image data. However, deep layer neural networks require large amounts of processing power to learn. Therefore, modern neural network training is performed using graphics cards, which typically possess many hundreds of small, modestly powerful cores that calculate massively in parallel. Readers will learn how to apply multiresolution analysis and modern deep learning neural network techniques to medical image analysis problems.
关键词： convolutional neural networks,skin lesions,multiresolution image analysis,computer-aided diagnosis,confocal laser scanning microscopy,machine learning
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 4th Advanced Information Technology, Electronic and Automation Control Conference (IAEAC) - Chengdu, China (2019.12.20-2019.12.22)] 2019 IEEE 4th Advanced Information Technology, Electronic and Automation Control Conference (IAEAC) - Research on Sparse Code Shrinkage denoise in Underwater 3D Laser Scanning Images
摘要： Noise removal is the pre-stage and essential step for many image processing tasks. Sometimes it is hard to have correct exposure for camera in underwater environment. In general, we need to have long exposure time to collect the weak light signal which increase the background electrical noise and higher than the signal. Underwater laser scanning is such special case with white laser stripe and dark background images. Hence, noise including which dots, lumps have heavy impact to our laser image. This paper discuss underwater laser scanning image denoise and presents the method based on Sparse code shrinkage algorithm to reduce such noise effect in ?nal reconstructed 3D model. The comparative study using natural and real 3D underwater scanning images is presented on the experimental section.
关键词： SCS,3D laser scanning,Image denoise,Underwater Images
更新于2025-09-19 17:13:59
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Use of the inferior whorl to detecting age-related changes in human corneal subbasal nerve plexus with laser-scanning confocal microscopy
摘要： Purpose: To determine the effect of aging on the corneal subbasal nerve plexus (SNP) by employing a wide-field mapping technique of composite images, scanned at the location of a distinctive spiraled subbasal nerve pattern located 1 to 2 mm inferior to the corneal apex (the inferior whorl) for SNP structural quantification. Material and methods: The central corneal tactile sensitivity (CCTS) and inferior whorl length (IWL) were compared among individuals in three age groups (20–39 years, 40–59 years, and 60–79 years). Statistical analyses constituted the Kruskal-Wallis test, one-way analysis of variance (with post hoc least significant difference test), Spearman correlation coefficient, and linear regression. Results: CCTS remained stable until the age of 50 years, when it began to decrease; the mean CCTS was 58.15±2.46 mm in the group aged 20–39, 55.74±3.85 mm in the group aged 40–59, and 50.23±3.27 mm in the group aged 60–79. IWL decreased with increasing age, with a corresponding linear decline of 0.2088 mm/mm2 per year, and the mean IWL was 25.43±4.50 mm/mm2 in the group aged 20–39, 22.71±6.19 mm/mm2 in the group aged 40–59, and 18.60±4.21 mm/mm2 in the group aged 60–79. Conclusion: Our work provided a more accurate and repeatable method for corneal nerve analysis using Laser-Scanning Confocal Microscopy (LSCM). By using this technique, we confirmed that aging is associated with progressive reduction in subbasal nerve length.
关键词： aging,subbasal nerve plexus,laser-scanning confocal microscopy,inferior whorl
更新于2025-09-19 17:13:59
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Combined Use of Terrestrial Laser Scanning and UAV Photogrammetry in Mapping Alpine Terrain
摘要： Airborne and terrestrial laser scanning and close-range photogrammetry are frequently used for very high-resolution mapping of land surface. These techniques require a good strategy of mapping to provide full visibility of all areas otherwise the resulting data will contain areas with no data (data shadows). Especially, deglaciated rugged alpine terrain with abundant large boulders, vertical rock faces and polished roche-moutones surfaces complicated by poor accessibility for terrestrial mapping are still a challenge. In this paper, we present a novel methodological approach based on a combined use of terrestrial laser scanning (TLS) and close-range photogrammetry from an unmanned aerial vehicle (UAV) for generating a high-resolution point cloud and digital elevation model (DEM) of a complex alpine terrain. The approach is demonstrated using a small study area in the upper part of a deglaciated valley in the Tatry Mountains, Slovakia. The more accurate TLS point cloud was supplemented by the UAV point cloud in areas with insu?cient TLS data coverage. The accuracy of the iterative closest point adjustment of the UAV and TLS point clouds was in the order of several centimeters but standard deviation of the mutual orientation of TLS scans was in the order of millimeters. The generated high-resolution DEM was compared to SRTM DEM, TanDEM-X and national DMR3 DEM products con?rming an excellent applicability in a wide range of geomorphologic applications.
关键词： terrestrial laser scanning,digital modelling,point cloud,UAV photogrammetry,alpine terrain
更新于2025-09-19 17:13:59
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Impact of Resolution and Texture of Laser Scanning Generated Three‐Dimensional Models on Landmark Identification
摘要： The aim of the study was to determine the impact of the resolution and texture of 3D models created through laser scanning on the measurement error (ME) of craniometric landmarks. Ten skulls were scanned at five different resolutions, and the generated 3D models were exported with and without texture. The 3D coordinates of 28 landmarks were derived. Each landmark was picked five times by one observer. The ME of a definite landmark was calculated as an average of distances between the repeated placements of the landmark by the observer and the landmark centroid. One-way ANOVA was applied for detection of significant differences in the MEs between and within landmark types recorded at different resolutions. The MEs of landmark types in textured and non-textured models were compared by a paired test. Twelve linear measurements were calculated as interlandmark distances and their values obtained on the models of different resolution were compared. The Frankfurt horizontal plane was constructed for each model and its deviation was calculated at different resolutions. Scan resolution impacted MEs of Type 1 and 2 landmarks, but not the precision level of Type 3 landmarks. Texture most influenced the precise identification of Type 1 landmarks. The interlandmark distances between Type 2 landmarks were most consistent in their values, those between Type 1 landmarks showed deviations in low-resolution models, and distances between Type 3 landmarks demonstrated various patterns of transition of the values throughout the resolutions. Altogether, the use of textured high-resolution models would be preferable in morphometric studies.
关键词： Laser scanning,3D model,craniometric landmarks,texture,measurement error,resolution
更新于2025-09-19 17:13:59
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Optical Fluorescence Diagnostic of Wheat Leaf Rust with Laser Scanning Confocal Microscopy
摘要： Wheat is the most important grain crop and food source worldwide. The management of diseases and early detection of pathogens is a crucial step in diagnosis programs in wheat. In the primary stage, the symptoms of rust fungus are difficult to identify with visual monitoring and other conventional techniques. In this study, we intended to investigate the early stage leaf rust in wheat crop produced through rust fungus using light fluorescence from laser scanning confocal microscopy (LSCM). The leaf rust and normal samples were analyzed with an excitation of 488 nm wavelength of Ar+ laser without any marker or photosensitizer. The small dark pores instead of stomata appears in leaf due to fungus infection and can be observed after two week of leaf tillering. These spots are orange or brown in the beginning and become black, when plants reach maturity. In recent study, the potential of non-invasive techniques for the detection of plant diseases are demonstrated for the development of a rapid and less complex early stage detection procedure that can be utilized to evaluate the infection structures during fungus infection of wheat. The newly developed rapid procedure will be helpful for early stage detection and management fungal infection before proper development during wheat interaction.
关键词： Wheat leaf rust,Optical sensors,Laser scanning confocal microscopy,Fungus infection
更新于2025-09-19 17:13:59
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Research on Fast Calculation Method of Complex Soil Yard Excavation Volume Based on 3D Laser Scanning
摘要： The measurement of earthwork excavation in hydropower project construction is an important control process in engineering construction. The traditional measurement and calculation process is not only inefficient, but also easy to cause errors. In this paper, the 3D laser scanner is applied to continuously measure the excavation process of the soil material yard and the efficient processing method of registration, compression and extraction process of excavation point cloud data is established respectively. At the same time, two fast calculation methods of excavation volume based on point cloud data are established. The practical application proves the data processing method established in this paper can shorten the data processing time by more than 80%, and ensure the accuracy of the data, and can control the calculation error of the excavation volume within 1%.
关键词： 3D laser scanning,point cloud data,volume calculation,earthwork excavation,hydropower project
更新于2025-09-19 17:13:59
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Individual Tree Crown Segmentation of a Larch Plantation Using Airborne Laser Scanning Data Based on Region Growing and Canopy Morphology Features
摘要： The detection of individual trees in a larch plantation could improve the management efficiency and production prediction. This study introduced a two-stage individual tree crown (ITC) segmentation method for airborne light detection and ranging (LiDAR) point clouds, focusing on larch plantation forests with different stem densities. The two-stage segmentation method consists of the region growing and morphology segmentation, which combines advantages of the region growing characteristics and the detailed morphology structures of tree crowns. The framework comprises five steps: (1) determination of the initial dominant segments using a region growing algorithm, (2) identification of segments to be redefined based on the 2D hull convex area of each segment, (3) establishment and selection of profiles based on the tree structures, (4) determination of the number of trees using the correlation coefficient of residuals between Gaussian fitting and the tree canopy shape described in each profile, and (5) k-means segmentation to obtain the point cloud of a single tree. The accuracy was evaluated in terms of correct matching, recall, precision, and F-score in eight plots with different stem densities. Results showed that the proposed method significantly increased ITC detections compared with that of using only the region growing algorithm, where the correct matching rate increased from 73.5% to 86.1%, and the recall value increased from 0.78 to 0.89.
关键词： airborne laser scanning (ALS),individual tree crown (ITC) segmentation,light detection and ranging (LiDAR),region growing,canopy morphology,larch plantation
更新于2025-09-19 17:13:59
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Review of mobile laser scanning target‐free registration methods for urban areas using improved error metrics
摘要： Registration is one of the most important tasks in mobile laser scanning (MLS) point cloud processing. This paper ?rstly reviews existing target-free matching techniques as well as methods to evaluate the quality of the registration. Next, a new error metric is introduced that takes into account the residuals of check planes as well as their orientation. Experiments using real datasets in combination with reference data were performed to evaluate the suitability of these metrics. The proposed error metric proved to be more suitable for evaluating the quality of point cloud registration than state-of-the-art equivalents. The results also indicate that least squares plane ?tting is the best technique for MLS point cloud registration.
关键词： point cloud matching,target-free registration,matching quality,error metric,mobile laser scanning
更新于2025-09-19 17:13:59