3D Scanning Research Articles

CLASSIFICATION OF DATA CAPTURING AND BUILDING SURVEYING TECHNIQUES IN THE CONTEXT OF SELECTING THE OPTIMAL METHOD OF CREATING 3D BIM AND HBIM MODELS OF EXISTING BUILDINGS

When creating a BIM information model of an existing building, a number of surveying techniques may be applied. The choice of particular technique depends largely on the budget of the investor commissioning the task and, on the specialist, commissioned to do it. Methods of conducting very accurate architectural survey and creating a digital 3D model are still fairly expensive due to the need of using specialist equipment. On the other hand, more common and affordable methods often lack the accuracy in the final model. This paper attempts to present a new classification of data capturing and building surveying techniques for creating 3D BIM models of existing buildings. The authors discuss optimal ways of applying particular methods and combining them so as to reduce the overall cost of the commissioned task and to achieve high accuracy of the final model at the same time. The analysis presented in this paper allows to introduce some order in the methods of creating BIM models of existing buildings by offering a new classification adjusted to standards currently used in architectural surveying.

Using a morph-based animation to visualise the face of Pharaoh Ramesses II ageing from middle to old age

Ramesses II was one of the most important Pharaohs to have presided over Egypt during the New Kingdom period. In 2023 researchers Wilkinson, Saleem, Liu and Roughley produced two digital 3D facial depictions showing Ramesses II at different ages: one around the age-at-death at 90 years old and the other, an age-regression at approximately 45 years old, based CT scans of his mummified remains, photographs, and historical information. The presence of two 3D facial depictions of one ancient individual at different ages affords an opportunity to show how Ramesses II might have looked during key moments of his lifetime and just prior to death. This paper describes the workflow adopted to add realistic textures to the facial depictions, and to use a morph-based animation to represent Ramesses II ageing from 45 to 90 years old.

Carapace Morphology Variations in Captive Tortoises: Insights from Three-Dimensional Analysis.

The carapace morphology of tortoises is a crucial characteristic used for species identification, with features such as shell shape, roughness, and color patterns varying among species. Understanding this morphological diversity is valuable not only for taxonomic classification but also for more specialized clinical approaches. This study investigated the morphological differences in the shells of Leopard tortoises (Stigmochelys pardalis), African spurred tortoises (Centrochelys sulcata), and Greek tortoises (spur-thighed tortoises; Testudo graeca) raised in captivity. Using 3D scanners, the carapaces were modeled, and a 3D geometric morphometric method was employed to analyze shape variations and dimensional features, with landmarks applied automatically. Among the species studied, African spurred tortoises had the largest carapace size. Principal component analysis (PCA) identified PC1 and PC3 as critical factors in distinguishing between species based on morphological characteristics. Positive PC1 values, associated with a shorter carapace height, indicated a flatter or more compact shell shape. A higher PC3 value corresponded to a raised shape at the back of the shell, while a lower PC3 value indicated a raised shape at the front. Specifically, Leopard tortoises exhibited a higher carapace shape than the other species, while African spurred tortoises had shorter carapaces. An allometric effect was observed in the carapaces, where smaller specimens tended to be proportionately higher-domed, whereas larger shells displayed a lower height in shape. These findings highlight the significance of shape variations in tortoise shells, which emerge during adaptation and have important implications for taxonomy and clinical practice. Such differences should be carefully considered in veterinary care and species identification.

The application of synthetic wollastonite in digital light processing 3D printing

In this study, 3D printable organic-inorganic resins were developed using glycerol dimethacrylate, which can be synthesised from glycerol obtained as a by-product of the biodiesel production process, and wollastonite synthesised from reagent-grade materials, the by-product of the aluminium fluoride manufacturing process, silica gel waste or natural rock. The developed recyclable waste-based material was proven to be compatible with the widely available desktop DLP 3D PICO2 39 printer. It allowed straightforward additive manufacturing of true 3D structures with sub-millimetre spatial definition using standard printing parameters. This opens the way for the production of inorganic objects from reusable industrial waste.

Digital Light Processing of Thermoresponsive Hydrogels from Polyproline-Based Star Polypeptides.

The first report of star poly(L-proline) crosslinkers is disclosed for digital light processing 3D printing of thermoresponsive hydrogels. Through chain end functionalization of star poly(L-proline)s with methacryloyl groups, access to high-resolution defined 3D hydrogel structures via digital light processing is achieved through photoinitiated free radical polymerization. Changing the poly(L-proline) molecular weight has a direct influence on both thermoresponsiveness and printability, while shape-morphing behavior can be induced thermally.

PCAlign: a general data augmentation framework for point clouds

With the advancement of 3D scanning technologies and deep learning theories, point cloud-based deep learning networks have gained considerable attention in the fields of 3D vision and computer graphics. Leveraging the rich geometric information present in 3D point clouds, these networks facilitate more accurate feature learning tasks. However, existing networks often suffer from generalization defects caused by variations in pose and inconsistent representations of training data. In this paper, we propose a novel data augmentation framework to overcome these limitations. Our approach utilizes principal component analysis (PCA) to generate four aligned copies of a point cloud. These copies are then input into a multi-channel structure, which is compatible with popular backbones of point cloud-based deep networks. Finally, the outputs of the multi-channel structure are merged to generate rotation-invariant feature learning results. Experimental evaluations demonstrate the efficacy of our framework, showcasing significant improvements in various existing point cloud-based deep learning methods. Notably, our method exhibits enhanced robustness in classification tasks, particularly when dealing with point clouds containing random pose variations and non-uniform densities. Project link: https://github.com/LAB123-tech/PCAlign.

Ergonomic glove pattern drafting method for hand assistive devices: considering 3D hand dimensions and finger mobility

Recently, interest has surged in glove-type assistive devices for relieving hand muscle stiffness caused by brain lesions. This study aims to develop an ergonomic method for drafting glove patterns intended for hand-assistive devices. To facilitate pattern development, we acquired three-dimensional (3D) scan data from the four hemiplegic patients while their hands were in a relaxed posture, which was subsequently transformed into two-dimensional (2D) data. Based on the 3D shape data, we analyzed the finger joint range of motion (ROM) and change ratio of skin surface length resulting from flexion and extension movements of the paralyzed hand. Incisions were strategically applied to regions displaying significant variations in these parameters. These flattened 2D patterns were then integrated into revised pattern blocks to enhance the shading data related to the 3D shape, resulting in the development of four glove patterns. We found that gloves prototyped using this innovative pattern-drafting method did not impede joint ROM when worn. Changes in clothing pressure inside the glove at the joints corresponded to the bending angles of the fingers, and the pressure did not exceed the discomfort threshold during hand flexion and extension movements. Importantly, participants provided positive subjective feedback concerning the comfort of the gloves. Our findings yield fundamental data for developing a foundational glove design for hand-assisted devices for patients with paralysis, achieved through the utilization of this novel ergonomic glove pattern-drafting method.

Stability of hot-finished and cold-formed steel hollow section columns: A comparative study

A comparative study into the buckling behaviour of hot-finished and cold-formed steel hollow section members subjected to axial compression is presented in this paper. The main differences between hot-finished and cold-formed hollow sections are initially discussed. An experimental programme conducted to investigate the local, global and local-global interactive buckling of hollow section columns is then described. Three S355 normalised hot-finished and three S355/S420 (dual certified) cold-formed profiles, covering circular, square and rectangular hollow sections (CHS, SHS and RHS respectively), were studied. The stress-strain characteristics of the examined materials were obtained through tensile coupon tests. 3D laser scanning was utilised to determine the distribution of geometric imperfections in selected SHS test specimens and a consistent approach to characterise different forms of geometric imperfections from the scan data is put forward. A stub column test was carried out on each cross-section to examine its local buckling behaviour, and a series of long column tests were performed on all test profiles. In total, 21 tensile coupon tests, six stub column tests and 40 long column tests were conducted in this programme. Finite element models were also developed, validated and used for parametric studies to generate supplementary numerical datasets. The obtained test and numerical data, along with the existing experimental results collected from the literature, were used to evaluate the accuracy and reliability of the Eurocode 3 (EC3) stability design provisions for hot-finished and cold-formed hollow section columns; aspects requiring improvements are highlighted to guide future studies.

Geometrical morphology and deformation measurement of long-span suspension bridge based on terrestrial laser scanning

Long-span suspension bridges necessitate deformation measurements for proper evaluation and upkeep. However, conventional approaches are unable to collect continuous spatial deformation data, which severely restricts their application in structural research. This paper presents a reliable and efficient method for measuring the deformation of suspension bridges using 3D laser scanning, including planning the scanning route, preprocessing the point cloud data, and extracting the deformation indicators. The method plans the scanning route based on experience and basic path planning principles to achieve both efficiency and precision, preprocesses the point cloud data by 3-stage denoising and curvature-based downsampling to preserve valuable point data better, and then proposes an extraction procedure for different types of deformation indicators. A field test on a typical long-span suspension highway bridge is performed, and the data processing and results extraction details are introduced. The accuracy and consistency of measurement results are discussed to verify the reliability of the proposed approach. The verified data provides useful information for the evaluation and maintenance of the bridge.

Adaptation and Biomechanical Performance of Custom-Fit Mouthguards Produced Using Conventional and Digital Workflows: A Comparative InVitro Strain Analysis.

The use of different models for the fabrication of custom-fit mouthguards (MTGs) can affect their final thickness, adaptation, and shock-absorption properties. This study aimed to evaluate the adaptation, thickness, and shock absorption of ethylene-vinyl acetate (EVA) thermoplastic MTGs produced using conventional plaster or three-dimensional (3D) printed models. A typical model with simulated soft gum tissue was used as the reference model to produce MTGs with the following two different protocols: plast-MTG using a conventional impression and plaster model (n = 10) and 3DPr-MTG using a digital scanning and 3D printed model (n = 10). A custom-fit MTG was fabricated using EVA sheets (Bioart) plasticized over different models. The MTG thickness (mm), internal adaptation (mm) to the typodontic model, and voids in the area (mm2) between the two EVA layers were measured using cone-beam computed tomography images and Mimics software (Materialize). The shock absorption of the MTG was measured using a strain-gauge test with a pendulum impact at 30° with a steel ball over the typodont model with and without MTGs. Data were analyzed using one-way analysis of variance with repeated measurements, followed by Tukey's post hoc tests. The 3DPr-MTG showed better adaptation than that of the Plast-MTG at the incisal/occlusal and lingual tooth surfaces (p < 0.001). The 3DPr-MTG showed a thickness similar to that of the Plast-MTG, irrespective of the measured location. MTGs produced using both model types significantly reduced the strain values during horizontal impact (3DPr-MTG 86.2% and Plast-MTG 87.0%) compared with the control group without MTG (p < 0.001). The MTGs showed the required standards regarding thickness, adaptation, and biomechanical performance, suggesting that the number and volume of voids had no significant impact on their functionality. Three-dimensional printed models are a viable alternative for MTG production, providing better adaptation than the Plast-MTG at the incisal/occlusal and lingual tooth surfaces and similar performance as the MTG produced with the conventional protocol.

Design and Fabrication of Low-Cost 3D Scanner Based on Photogrammetry for Mechanical Components

Design and Fabrication of Low-Cost 3D Scanner Based on Photogrammetry for Mechanical Components

Foam density measurement using a 3D scanner

In this work, we used a 3D scanner for the volume measurement of foamed samples, a long-standing problem in the density evaluation of foams. The 3D scanning density measurement method can be selected as an alternative to or in combination with well-established, classical methods that involve the use of instruments like a caliper, a pycnometer, or other devices based on displacement or flotation principles. In particular, the classical methods show some limitations when the foamed sample geometry is irregular, when the polymer is highly hygroscopic, and when it has open porosities. We have tested numerous foamed samples of different sizes, shapes, densities, materials, and morphologies. We utilized different 3D scanner configurations for their volume measurement and compared the results with geometrical and displacement methods, when possible. Results showed that the proposed method is highly accurate, reproducible, and simple, although some specific precautions should be put in place to avoid misinterpretation by the shape-reconstructing software.

High Agreement Between 3D Motion Capture and 2D Video Analysis Systems and Raters for Knee Flexion Range of Motion During A Single Leg Drop Landing Task

OBJECTIVE: To determine the agreement between a 2-dimensional (2D) and 3-dimensional (3D) video capture system and between multiple raters during a single leg drop landing task. DESIGN: Cross-sectional observational study METHODS: Single leg drop landing trials of twenty-three males (n=12) and females (n=11) were recorded using the 2D and 3D systems. Reliability and agreement were quantified through intraclass correlation coefficients (ICC2, k), standard error of the measurement (SEM), and Bland-Altman plots. Analysis of variance (ANOVA) assessed systematic error between the 2D raters and 3D system. RESULTS: A one-way ANOVA on 35 drop-landing trials across raters detected a difference across the 3 estimates of knee flexion range of motion (p&lt;0.001) where rater 1 did not differ (mean difference ± standard error: 1.15±0.48°, p=0.54) from the 3D system, rater 2 &gt; 3D system (3.30±0.76°, p&lt;0.001), and rater 1 and 2 differed (2.14±0.82°, p=0.04). There was high reliability between the two 2D raters (ICC2, k=0.89; SEM=3.44°). Rater 1 completed analyses on 87 additional trials (total n=117) and was comparable to the 3D system (0.87±0.47°, p=0.06; ICC2, k=0.90; SEM=3.52°). CONCLUSION: 2D video analysis can be used in a clinical setting where 3D capture of movement mechanics is not feasible.

Automated Idiopathic Normal-Pressure Hydrocephalus Diagnosis via Artificial Intelligence-Based 3D T1 MRI Volumetric Analysis.

Idiopathic normal pressure hydrocephalus (iNPH) is reversible dementia, that is underdiagnosed. The purpose of this study was to develop an automated diagnostic method for iNPH using artificial intelligence techniques with a T1-weighted MRI scan. We quantified iNPH, Parkinson's disease, Alzheimer's disease, and healthy control patients on T1-weighted 3D brain MRI scans using 452 scans for training and 110 scans for testing. Automatic component measurement algorithms were developed for Evans' index, Sylvian fissure enlargement, high-convexity tightness, callosal angle, and normalized lateral ventricle volume. XGBoost models were trained for both automated measurements and manual labels for iNPH prediction. A total of 452 patients (200 men; mean age ± standard deviation, 73.2 ± 6.5 years) were included in the training set. Of the 452 patients, 111 (24.6%) had iNPH. We obtained AUC values of 0.956 for automatically measured high-convexity tightness and 0.830 for Sylvian fissure enlargement. Intra-class correlation values of 0.824 for the callosal angle and 0.924 for Evans' index were measured. Using the decision tree of the XGBoost model, the model trained on manual labels obtained an average cross-validation AUC of 0.988 on the training set and 0.938 on the unseen test set, while the fully automated model obtained a cross-validation AUC of 0.983 and an unseen test AUC of 0.936. We demonstrated a machine-learning algorithm capable of diagnosing iNPH from a 3D T1-weighted MRI scan that is robust to the failure. We propose a method to scan large numbers of 3D T1-weighted MRI scans with minimal human intervention, making possible large-scale iNPH screening. iNPH = idiopathic normal-pressure hydrocephalus; PD = Parkinson's disease; AD = Alzheimer's disease; HC = healthy control; CSF = cerebrospinal fluid; DESH = disproportionately enlarged subarachnoid space hydrocephalus; 3D = three-dimensional.

Measurement of bending deformation of sheet metal using machine vision

ABSTRACT The aim of this study is to propose a fast and effective method to measure the curvature distribution and bending angle of sheet metal in the bending deformation using machine vision. An open-source computer vision library (OpenCV) was used for image processing. First, the image is calibrated for perspective and lens distortion. After that, the image is subjected to color extraction and binary conversion. The outer geometry of the material was obtained using edge detection. With the proposed method, the bending angle and curvature distribution in the four-point bending and V-bending tests are measured. The proposed machine vision method exhibits errors of 0.55% and 0.12% compared with the 3D scanner measurements for the bending angle in the four-point bend and V-bend tests after springback, respectively. The curvature distribution in bending deformation was also obtained. As an application of the proposed method, the moment – curvature diagram of the material was determined based on the obtained curvature at the center. Additionally, the optimal stroke was calculated for the target bend angle during the V-bending process. The proposed method proved to be an accurate and efficient way to measure bending deformation of sheet metal.

Employing 3D laser scanner for automated morphological assessment of aggregates produced from diverse sources and by different crushing methods

This study introduced an automated approach employing 3D scanner for quick and precise aggregates shape analysis. Recognizing existing gaps, there is still an industry demand to propose a standardized method for measuring material characteristics using 3D scanning. By addressing the limitations of previous studies, this research considered unexplored aspects of 3D scanning to improve the speed and efficiency of that. This research comprehensively examined nearly 1500 aggregates from five natural sources and five types of slag. Four statistical tests named Mann-Whitney U, Kolmogorov-Smirnov, Bootstrap, and Permutation were utilized to determine the optimal sample size for scanning. The findings suggest that scanning just 100 aggregates from each source is sufficient to be a small representative of the whole dataset and it can significantly reduce resource use while maintaining data integrity. As a practical insight, it has tried to scan a batch of 25 aggregates simultaneously in one session which could improve efficiency of scanning by reducing the processing time to just 0.6 min per particle. In MATLAB® software, some common bounding volume techniques such as Axis-Aligned, Oriented, Ellipsoid, and Sphere Bounding Box were used to analyze morphological properties. The findings showed that the aggregates sourced from Basalt, Moraine, and most of slags have more cubical shapes, while Porphyrit and Diabase aggregates are more elongated, flaky, and angular. This study also provided a comparative study of how various techniques for stone crushing affect the morphology of aggregates. The results indicate that a combination of jaw, cone, and horizontal impact crusher produces more spherical and cubical aggregates. Replacing of the cone crusher with a gyratory crusher in the same combination can improve elongation and sphericity slightly but may increase flaky particles. These insights offer valuable guidelines for future research and practical applications in construction material optimization.

Corrosion behaviour of 110SS steel in hydrochloric acid and blended acid system at 200°C

The influence of organic acids (formic acid, acetic acid) on the corrosion behaviour of 110SS steel, a hydrogen sulphide corrosion resistant alloy steel, in hydrochloric (HCl) acid environments was studied. The corrosion rates of 110SS steels in HCl acid and blended acid were measured using the high-temperature and high-pressure corrosion tester. Scanning electron microscopy was utilised to observe the morphology of corrosion products on steel samples corroded by different acid systems, and the energy dispersive X-ray spectrometer was used to analyse the elemental composition of the corrosion products. The corrosion morphology was observed using a 3D laser scanner. The results indicated that the corrosion rate of 110SS steel in HCl acid at 200 °C was an exponential function of HCl concentration. Reducing the HCl concentration significantly decreased the corrosion rate of 110SS steel. Organic acids and corrosion inhibitors synergistically reduced the corrosion of 110SS steel in HCl acid. Adding 3 wt.% organic acid to the 15 wt.% HCl acid system further reduced the corrosion rate, with a more pronounced effect observed in the HCl–formic acid system compared to the HCl–acetic acid system. Organic acids chemically adsorbed onto the steel surface and decomposed to produce CO, which hindered the attack of hydrogen ions on the metal. The added corrosion inhibitor and intensifier Sb2O3 resulted in the formation of a compact adsorption film on the steel surface, further inhibiting corrosion. The optimal mass ratio of HCl acid to organic acid was found to be 15% to 3%.

Using Experiments, 3D Scanning, and CFD to Analyze the Variance in Energy Losses Through Pipe Elbows

Pipe bends, or elbows, cause energy loss in pipelines due to the flow conditions they create. This energy loss has traditionally been approximated based on published minor loss coefficients, known as k-factors. However, the energy losses of elbows can vary based on geometric characteristics, which may not be accounted for in the published k-factors. The purpose of this research was to quantify the variance in energy loss resulting from elbows with geometric differences and to determine appropriate methods for approximating these variances using computational fluid dynamics (CFD). Eight polyvinyl chloride (PVC) elbows were physically tested in a hydraulic laboratory to determine the individual loss coefficients. The resulting data show that the minor loss coefficient k for two short-radius elbows of the same nominal size can vary by up to 51%. The same tests on two of the elbows were repeated using CFD, in which they were modeled two different ways: 1) using the ideal geometry and 2) using the actual geometry. The actual geometry was captured using 3D scanning. Each geometry was used in a series of simulations, and the results were compared to the experimental data. The CFD simulations were able to reproduce similar variances between the two elbows as displayed in the physical tests, although they were unable to reproduce the same k-factors. When compared to the experimental k-factor data, using the actual geometries captured by 3D scanning was not consistently more accurate than using idealized geometries.

Digitization and Protection of Cultural Heritage in Crises and Conflicts

The research focuses on digitization as a mechanism to protect cultural heritage in crisis and conflict situations, emphasizing technologies such as 3D scanning and virtual reality. The application of these methods in projects such as CyArk, Anqa and The Aleppo Project illustrates their potential to protect priceless cultural assets, highlighting the importance of global cooperation and innovation in technology as key factors in protecting cultural heritage for future generations.

Impact of the orofacial muscular rehabilitation exercise on facial expression recovery post-orthognathic surgery

ObjectiveThis study aimed to evaluate the impact of myofunctional rehabilitation of the orofacial muscles through specific exercises on the recovery of facial expression in patients following orthognathic surgery. Material and MethodsThe study included 62 patients who underwent Le Fort I and sagittal split ramus osteotomy (SSRO). Patients were divided into two groups: the first group started immediate post-operative myofunctional rehabilitation of the orofacial muscles through specific exercises. In contrast, patients in Group II did not undergo any myofunctional rehabilitation post-operative exercises. The recovery of facial expressions postoperatively was evaluated in both calm and smiling states by comparing the differences between 3D facial scanning data of chosen facial anatomical structures collected at five key time points: pre-surgery (D0), 2 days (D2), 14 days (D14), 1 month (D30), and 3 months (D90) postoperatively. ResultsThe analysis revealed that characteristic angles and lengths experienced significant changes post-surgery, with ∠chRnchL and ∠chRsnchL decreasing at D2 and normalizing by D30 in the experimental group, while the control group showed a slower recovery, normalizing by D90. The ChL-R length decreased at D2, returning to normal by D30 in the experimental group and D90 in the control group. The height Li-Ls increased at D2 and normalized by D30 in calm and smiling expressions across single and double jaw surgery patients. These findings underscore the more rapid recovery in the experimental group compared to the control group (P < 0.05; P < 0.005; P < 0.0001). ConclusionInitiating myofunctional rehabilitation immediately following orthognathic surgery enhances facial muscle function recovery, improves patient confidence, and expedites social reintegration. This approach is crucial for functional and psychological benefits.