Search Results (4,944)

Light Field Angular Super-Resolution (LFASR) addresses the issue where Light Field (LF) images can not simultaneously achieve both high spatial and angular resolution due to the limited resolution of optical sensors. Since Spatial-Angular Correlation (SAC) features are closely related to the structure of LF images, its accurate and complete extraction is crucial for the quality of LF images reconstructed by the LFASR method based on Deep Neural Networks (DNNs). In low-angular resolution LF images, SAC features must be extracted from a limited number of pixels that are at a great distance from each other and exhibit strong correlations. However, existing LFASR methods based on DNNs fail to extract SAC features accurately and completely. Due to the limited receptive field, methods based on regular Convolutional Neural Networks (CNNs) are unable to capture SAC features from distant pixels, leading to incomplete SAC feature extraction. On the other hand, methods based on large convolution kernels and attention mechanisms use an excessive number of pixels to extract SAC features, resulting in insufficient accuracy in extracted SAC features. To solve this problem, we introduce Deformable Convolutional Network (DCN), which adaptively changes the position of limited sampling point using offsets, so as to extract SAC from distant pixels. In addition, in order to make the offset of DCN more accurate and further improve the accuracy of SAC features, we also propose a Multi-Maximum-Offsets Fusion DCN (MMOF-DCN). MMOF-DCN can reduce the exploration range of finding the desired offset, thereby improving the offset finding efficiency. Experiment results show that our proposed method has advantages in real-world dataset and synthetic dataset. The PSNR value in synthetic dataset which have large disparity is improved by 0.45 dB compared to existing methods. Full article

Toll-like receptors (TLRs) are pivotal in modulating immune responses and have been implicated in bone remodeling. This in vivo study investigates the impact of TLR2 and TLR4 signaling on trabecular bone structure using micro-computed tomography in a murine model. Sacrum and lumbar vertebrae (L5, L6) from wildtype (WT), TLR2-knockout (TLR2-KO), and TLR4-knockout (TLR4-KO) mice were analyzed, with trabecular parameters such as connectivity density (Conn-Dens), trabecular thickness (DT-TbTh), and variability metrics (DT-Tb,(1/N),SD and DT-TbThSD) assessed. The results revealed significant differences among genotypes: TLR4-KO mice exhibited increased variability in trabecular distribution, indicating less stable bone structures, while TLR-KO mice showed lower variability in trabecular thickness, suggesting enhanced uniformity and robustness. BV/TV and 3D reconstructions highlighted lower bone volume fractions in the sacrum compared to lumbar vertebrae across genotypes, consistent with human observations of reduced sacral bone volume in spondyloarthritis (SpA). Interestingly, bone changes were independent of immunization-induced SpA, emphasizing a direct role in TLR signaling. These findings provide novel insights into the role of TLRs in bone microarchitecture and suggest implications for bone-related pathologies, particularly those involving inflammatory pathways. Future research may explore the translational relevance of TLR-mediated mechanisms in osteopenia and osteoporosis. Full article

Background: Myxol, a monocyclic carotenoid with β- and ψ-end groups, has been identified in only a limited number of bacteria, such as flavobacteria and cyanobacteria. Despite its biological significance, the biosynthetic pathway of myxol is not well understood, and studies on its physiological functions and biological activities are limited because of its rarity. Methods: BLAST homology searches for carotenoid biosynthesis genes in the genome of Nonlabens were performed. The carotenogenesis-related genes in the genome of the marine flavobacteria Nonlabens spongiae were individually cloned and functionally characterized using a heterologous Escherichia coli expression system. Carotenoids from N. spongiae were identified using an LC-MS analysis. Results: We identified a gene cluster involved in carotenoid biosynthesis in the genome of N. spongiae. This cluster includes genes encoding phytoene synthase (CrtB), phytoene desaturase (CrtI), lycopene cyclase (CrtY), carotenoid 1,2-hydratase (CruF), carotenoid 3,4-desaturase (ψ-end group) (CrtD), carotenoid 2-hydroxylase (ψ-end group) (CrtA-OH), and carotene hydro-xylase (CrtZ). Based on the characteristics of these enzymes, the primary products were predicted to be myxol and/or zeaxanthin. A spectroscopic analysis confirmed that myxol was the primary carotenoid. Furthermore, a plasmid containing a reconstructed gene cluster and geranylgeranyl pyrophosphate synthase (CrtE) located outside the cluster was introduced into E. coli. This system predominantly accumulated myxol, indicating that the reconstructed gene cluster enabled efficient myxol production in E. coli. Conclusions: This study highlighted the potential biotechnological applications of the carotenoid biosynthesis gene clusters for myxol production. Full article

Integrating LiDAR and photogrammetry offers significant potential for ensuring the accuracy and completeness of the 3D models of existing structures, which are essential for several applications in the architectural, engineering, and construction (AEC) industry. This study has two primary objectives: the first is to demonstrate how LiDAR and photogrammetry complement each other, through the balance of LiDAR’s structural accuracy with photogrammetry’s rich texture data; the second is to validate the quality of the resulting mesh by using it for the CFD simulation of wind flow around a case study building. The integration method, though simple, is optimized to ensure high-quality point cloud registration, minimizing data quality impacts. To capitalize on the advantages of both manual and full point-cloud-based modeling methods, the study proposes a new hybrid approach. In the hybrid approach, the large-scale and simplified parts of the geometry are modeled manually, while the complex and detailed parts are reconstructed using high-resolution point cloud data from LiDAR and photogrammetry. Additionally, a novel region of constraints method (ROCM) is introduced to streamline wind flow simulations across varying scenarios without the need for multiple meshes. The results indicate that the integrated approach was able to capture the complete and detailed geometry of the case study building, including the complex window extrusions. The CFD simulations revealed differences in the wind flow patterns and pressure distributions when compared across different geometry modeling approaches. It was found that the hybrid approach is the best and balances efficiency, accuracy, and computational cost. Full article

Vegetation characteristics significantly influence the impact of wildfires on individual building structures, and these effects can be systematically analyzed using heat transfer modelling software. Close-range light detection and ranging (LiDAR) data obtained from uncrewed aerial systems (UASs) capture detailed vegetation morphology; however, the integration of dense vegetation and merged canopies into three-dimensional (3D) models for fire modelling software poses significant challenges. This study proposes a method for integrating the UAS–LiDAR-derived geometric features of vegetation components—such as bark, wooden core, and foliage—into heat transfer models. The data were collected from the natural woodland surrounding an elevated building in Samford, Queensland, Australia. Aboveground biomass (AGB) was estimated for 21 trees utilizing three 3D tree reconstruction tools, with validation against biomass allometric equations (BAEs) derived from field measurements. The most accurate reconstruction tool produced a tree mesh utilized for modelling vegetation geometry. A proof of concept was established with Eucalyptus siderophloia, incorporating vegetation data into heat transfer models. This non-destructive framework leverages available technologies to create reliable 3D tree reconstructions of complex vegetation in wildland–urban interfaces (WUIs). It facilitates realistic wildfire risk assessments by providing accurate heat flux estimations, which are critical for evaluating building safety during fire events, while addressing the limitations associated with direct measurements. Full article

Identification of paleoclimate oscillation from various climate proxies across different regions is important for the mechanistic research of paleoclimate. Phytoliths from the lacustrine sediment of central NE China were extracted for paleoclimate reconstruction and abrupt event recognition. The combined phytolith assemblages; indices of Iw, Iph, D/P, Pi/P, and T/P; and the 66.4% PCA information with 95% confidence ellipse showed six global synchronously paleo-stages in the past 25,000 years: mixed coniferous broadleaf forest in a semi-humid cool climate (25,165–22,180 cal aB.P.), cold and arid steppe (22,180–18,080 cal aB.P.), semi-humid and semi-arid steppe (18,080–11,380); semi-humid cool grassland (11,380–7790 cal aB.P.), humid warm forest steppe (7790–4300 cal aB.P.), and semi-arid and cool meadow steppe (4300 cal aB.P. to the present). The global abrupt events of the 4.2-kiloyear event, 8.2-kiloyear event, Younger Dryas (YD), Heinrich1 (H1), and Heinrich2 (H2) were also captured by phytolith indices. The regional character of the reduction in humidity of the YD might have been affected by the combined influence of the Okhotsk High and the surrounding mountains. These findings not only strengthen phytolith palaeoresearch but also provide basic information for the mechanistic research of palaeoclimate in the edge area of Northeast Asia and promote global climate change research. Full article

Image-based 3D reconstruction enables robot-assisted interventions and image-guided navigation, which are emerging technologies in laparoscopy. When a robotic arm guides a laparoscope for image acquisition, hand–eye calibration is required to know the transformation between the camera and the robot flange. The calibration procedure is complex and must be conducted after each intervention (when the laparoscope is dismounted for cleaning). In the field, the surgeons and their assistants cannot be expected to do so. Thus, our approach is a procedure for a robot-based multi-view 3D reconstruction without hand–eye calibration, but with pose optimization algorithms instead. In this work, a robotic arm and a stereo laparoscope build the experimental setup. The procedure includes the stereo matching algorithm Semi Global Matching from OpenCV for depth measurement and the multiscale color iterative closest point algorithm from Open3D (v0.19), along with the multiway registration algorithm using a pose graph from Open3D (v0.19) for pose optimization. The procedure is evaluated quantitatively and qualitatively on ex vivo organs. The results are a low root mean squared error (1.1–3.37 mm) and dense point clouds. The proposed procedure leads to a plausible 3D model, and there is no need for complex hand–eye calibration, as this step can be compensated for by pose optimization algorithms. Full article

Traditional facial recognition is realized by facial recognition algorithms based on 2D or 3D digital images and has been well developed and has found wide applications in areas related to identification verification. In this work, we propose a novel live face detection (LFD) method by utilizing snapshot spectral imaging technology, which takes advantage of the distinctive reflected spectra from human faces. By employing a computational spectral reconstruction algorithm based on Tikhonov regularization, a rapid and precise spectral reconstruction with a fidelity of over 99% for the color checkers and various types of “face” samples has been achieved. The flat face areas were extracted exactly from the “face” images with Dlib face detection and Euclidean distance selection algorithms. A large quantity of spectra were rapidly reconstructed from the selected areas and compiled into an extensive database. The convolutional neural network model trained on this database demonstrates an excellent capability for predicting different types of “faces” with an accuracy exceeding 98%, and, according to a series of evaluations, the system’s detection time consistently remained under one second, much faster than other spectral imaging LFD methods. Moreover, a pixel-level liveness detection test system is developed and a LFD experiment shows good agreement with theoretical results, which demonstrates the potential of our method to be applied in other recognition fields. The superior performance and compatibility of our method provide an alternative solution for accurate, highly integrated video LFD applications. Full article

This paper presents three 3D reconstructions of different analogue models used to reproduce, interpret, and describe the geological setting of a seismogenic area in Southern Italy—the Messina Strait. Three-dimensional analysis is a technique that allows for less sparse and more congruent and coherent information about a study zone whose complete understanding reduces uncertainties and risks. A thorough structural and geodynamic description of the effects of low-angle normal faulting in the same region through analogue models has been widely investigated in the scientific literature. Sandbox models for fault behaviour during deformation and the effects of a Low Angle Normal Fault (LANF) on the seismotectonic setting are also studied. The deformational patterns associated with seismogenic faults, rotational behaviour of faults, and other related problems have not yet been thoroughly analysed. Most problems, like the evolution of normal faults, fault geometry, and others, have been cited and briefly outlined in earlier published works, but a three-dimensional approach is still significant. Here, we carried out a three-dimensional digital model for a complete and continuous structural model of a debated, studied area. The aim of this study is to highlight the importance of fully representing faults in complex and/or non-cylindrical structures, mainly when the shape and dimensions of the fault(s) are key parameters, like in seismogenic contexts. Full article

High-resolution RGB-D sensors are widely used in computer vision, manufacturing, and robotics. The depth maps from these sensors have inherently high measurement uncertainty that includes both systematic and non-systematic noise. These noisy depth estimates degrade the quality of scans, resulting in less accurate 3D reconstruction, making them unsuitable for some high-precision applications. In this paper, we focus on quantifying the uncertainty in the depth maps of high-resolution RGB-D sensors for the purpose of improving 3D reconstruction accuracy. To this end, we estimate the noise model for a recent high-precision RGB-D structured light sensor called Zivid when mounted on a robot arm. Our proposed noise model takes into account the measurement distance and angle between the sensor and the measured surface. We additionally analyze the effect of background light, exposure time, and the number of captures on the quality of the depth maps obtained. Our noise model seamlessly integrates with well-known classical and modern neural rendering-based algorithms, from KinectFusion to Point-SLAM methods using bilinear interpolation as well as 3D analytical functions. We collect a high-resolution RGB-D dataset and apply our noise model to improve tracking and produce higher-resolution 3D models. Full article

The phenotypic parameters of root systems are vital in reflecting the influence of genes and the environment on plants, and three-dimensional (3D) reconstruction is an important method for obtaining phenotypic parameters. Based on the characteristics of root systems, being featureless, thin structures, this study proposed a skeleton-based 3D reconstruction and phenotypic parameter measurement method for root systems using multi-view images. An image acquisition system was designed to collect multi-view images for root system. The input images were binarized by the proposed OTSU-based adaptive threshold segmentation method. Vid2Curve was adopted to realize the 3D reconstruction of root systems and calibration objects, which was divided into four steps: skeleton curve extraction, initialization, skeleton curve estimation, and surface reconstruction. Then, to extract phenotypic parameters, a scale alignment method based on the skeleton was realized using DBSCAN and RANSAC. Furthermore, a small-sized root system point completion algorithm was proposed to achieve more complete root system 3D models. Based on the above-mentioned methods, a total of 30 root samples of three species were tested. The results showed that the proposed method achieved a skeleton projection error of 0.570 pixels and a surface projection error of 0.468 pixels. Root number measurement achieved a precision of 0.97 and a recall of 0.96, and root length measurement achieved an MAE of 1.06 cm, an MAPE of 2.37%, an RMSE of 1.35 cm, and an R² of 0.99. The whole process of reconstruction in the experiment was very fast, taking a maximum of 4.07 min. With high accuracy and high speed, the proposed methods make it possible to obtain the root phenotypic parameters quickly and accurately and promote the study of root phenotyping. Full article

Objective: This study aims to investigate the mechanical behavior of titanium (Ti6Al4V) mini-implants (MIs) under varying orthodontic forces using finite element analysis (FEA) and to evaluate their performance and durability under realistic clinical conditions. Optimal orthodontic forces significantly influence the structural integrity and functional longevity of MIs while minimizing adverse effects on surrounding bone tissues. Materials and Methods: A commercially available MI (diameter: 2.0 mm, length: 12 mm) was modeled using FEA. The mandible geometry was obtained using computed tomography (CT) scanning, reconstructed in 3D using SpaceClaim software 2023.1, and discretized into 10-node tetrahedral elements in ANSYS Workbench. Material properties were assigned based on the existing literature, and the implant–bone interaction was simulated using a nonlinear frictional contact model. Orthodontic forces of 2 N and 10 N, inclined at 30°, were applied to simulate clinical loading conditions. Total displacement, von Mises stresses, equivalent strains, fatigue life, and safety factors were analyzed to assess the implant’s mechanical performance. Results: At 2 N, the MI demonstrated minimal displacement (0.0328 mm) and sustained approximately 445,000 cycles under safe fatigue loading conditions, with a safety factor of 4.8369. At 10 N, the implant’s lifespan was drastically reduced to 1546 cycles, with significantly elevated stress (6.468 × 10⁵ MPa) and strain concentrations, indicating heightened risks of mechanical failure and bone damage. The findings revealed the critical threshold beyond which orthodontic forces compromise implant stability and peri-implant bone health. Conclusions: This study confirms that maintaining orthodontic forces within an optimal range, approximately 2 N, is essential to prolong MI lifespan and preserve bone integrity. Excessive forces, such as 10 N, lead to a rapid decline in durability and increased risks of failure, emphasizing the need for calibrated force application in clinical practice. These insights provide valuable guidance for enhancing MI performance and optimizing orthodontic treatment outcomes. Full article

In three-dimensional (3D) measurement, the motion of objects inevitably introduces errors, posing significant challenges to high-precision 3D reconstruction. Most existing algorithms for compensating motion-induced phase errors are tailored for object motion along the camera’s principal axis (Z direction), limiting their applicability in real-world scenarios where objects often experience complex combined motions in the X/Y and Z directions. To address these challenges, we propose a universal motion error compensation algorithm that effectively corrects both pixel mismatch and phase-shift errors, ensuring accurate 3D measurements under dynamic conditions. The method involves two key steps: first, pixel mismatch errors in the camera subsystem are corrected using adjacent coarse 3D point cloud data, aligning the captured data with the actual spatial geometry. Subsequently, motion-induced phase errors, observed as sinusoidal waveforms with a frequency twice that of the projection fringe pattern, are eliminated by applying the Hilbert transform to shift the fringes by π/2. Unlike conventional approaches that address these errors separately, our method provides a systematic solution by simultaneously compensating for camera-pixel mismatch and phase-shift errors within the 3D coordinate space. This integrated approach enhances the reliability and precision of 3D reconstruction, particularly in scenarios with dynamic and multidirectional object motions. The algorithm has been experimentally validated, demonstrating its robustness and broad applicability in fields such as industrial inspection, biomedical imaging, and real-time robotics. By addressing longstanding challenges in dynamic 3D measurement, our method represents a significant advancement in achieving high-accuracy reconstructions under complex motion environments. Full article

Study Design: This is an experimental feasibility study. Objective: The objective was to analyze the potential of open-source freeware (OSF) to train residents in virtual surgical planning (VSP) and compare this workflow with commercially available software (CAS). Methods: A workflow for mandibular reconstruction with a fibular free flap (FFF) was developed in 3D-Slicer^® and Blender^® and compared to our clinical workflow in Materialise Mimics Innovation Suite version 25 (Materialise InPrint^®, ProPlan CMF^® and 3-Matic^®). Five CMF residents, inexperienced in VSP, were trained to use both the OSF and CAS workflows and then performed four planning sessions on OSF and CAS. The duration (minutes) and the amount of mouse clicks (MCs) of every step in the workflow were recorded. Afterwards, the experience with VSP was investigated with the System Usability Scale (SUS) and a self-developed questionnaire. Results: The total VSP time with CAS took 91 ± 15 min and needed 2325 ± 86 MCs compared to 111 ± 26 min and 1876 ± 632 MCs for OSF, respectively. The questionnaire had an 80% response rate. The SUS for CAS was 67.5 compared to 50 for OSF. The participants believe it is extremely valuable to learn VSP during their training and to be able to perform VSP as a surgeon. Conclusion: We believe OSF can be a cost-effective alternative compared to CAS for the training of surgical residents to gain insight in complex surgeries and to better understand CAD limitations and possibilities. Full article

Our group has previously demonstrated that tissue-engineered dermis containing cultured fibroblasts or adipose-derived stromal vascular fraction cells is superior to artificial dermis in terms of scar quality for covering facial defects. However, using these cells for clinical applications requires Food and Drug Administration approval and involves complex procedures for cell culture or isolation. This retrospective study aimed to compare effects of tissue-engineered dermis containing micronized adipose tissue (MAT) and artificial dermis for facial reconstruction. Tissue-engineered dermis consisting of MAT seeded on artificial dermis was applied in 30 cases, while artificial dermis without MAT was grafted in 35 cases. Healing time and severities of scar contraction, color mismatch, and landmark distortion at one year after healing were evaluated. Wounds in the tissue-engineered dermis group re-epithelialized in 30.0 ± 4.3 days compared to 34.3 ± 5.4 days in the artificial dermis group (p < 0.05). The average dE2000 score in color mismatch analysis was 4.9 ± 1.7 in the tissue-engineered dermis group and 5.1 ± 1.7 in the artificial dermis group (p = 0.57). The extent of scar contraction was 16.2 ± 12.3% in the tissue-engineered dermis group and 23.2 ± 12.8% in the artificial dermis group (p < 0.05). The average severity grade of landmark distortion was 0.20 ± 0.50 in the tissue-engineered dermis group and 0.50 ± 0.71 in the artificial dermis group (p < 0.05). These findings indicate that tissue-engineered dermis grafts containing MAT are superior to artificial dermis grafts for facial reconstruction in terms of healing time, scar contraction, and landmark distortion severity. However, there was no significant difference in color mismatch between the two groups. Full article