3D scanning

Over the years, high attention has been paid to Reverse Engineering (RE) as a methodological approach for reconstructing 3D models of existing objects to carry out analyses aimed to estimate accurate products performance and to conduct accurate inspections and quality controls. Although these techniques are widely used, RE has limitations related to both the user's operations and the range of high-quality acquisition. Consequently, large objects exclude the possibility of preserving scanning accuracy, unless alternative solutions are found, and require high repeatability, making necessary well-trained personnel. For these purposes, Extended Reality (XR) could pave the way for the development of advanced training systems and the implementation of optimized interfaces for testing the adopted design solutions. This research deals with the development of an XR application for simulating the 3D scanning process of the vertical stabilizer torque box of an airplane and providing both an effective virtual training tool for the operators and a supporting tool for testing design solutions.

Keywords: 3D scanning , Extended Reality , Virtual training

The demand for orthodontic and aesthetic treatments, aimed at having healthier teeth and more beautiful smiles, is increasingly growing. The devices on which these treatments are based must be rigorously bespoke for each patient. This is amplifying the need to develop digitized workflows, ranging from scanning to Additive Manufacturing (AM). The present work proposes an alternative workflow for designing and manufacturing orthodontic aligners, also known as clear aligners, starting from the intraoral scanning of the patient's dentition. Orthodontic aligners are an alternative to metal brackets to correct dental malocclusions and they are often preferred by the patients because of their lower impact on facial aesthetics and for their higher comfort. The orthodontic treatments based on the aligners utilize a series of aligners, each one with a geometry slightly different from the previous one. The use of the single aligners is aimed to apply a force to the teeth and gradually aligning them until the end of the treatment. The workflow we propose in the present study is based on the following three main stages: intraoral scanning of the patient's dentition, design of the aligners through a semi-automatic algorithm, and the direct additive manufacturing of the aligners through VAT photopolymerization technique. The possibility to directly additive manufacturing the aligners allows us to rethink the current orthodontic treatments. The aligners geometry can be re-designed, with the possibility of locally manipulating the thickness. This approach would allow the regulation of the amount of force applied locally to the tooth, thus optimizing the treatment and its duration. A feasibility study of the proposed workflow is reported in the present paper, with a focus on the semi-automatic design algorithm and on the additive manufacturing process of the aligners.

Keywords: Additive Manufacturing , Bespoke Medical Devices , Dental Appliances , Design Algorithms for Medical Applications , DfAM

The human hand is a versatile and complex body part. It permits difficult movements with various degrees of precision and force. Several causes can lead to upper limb damage, including musculoskeletal disorders and diseases like stroke. The impairment can affect daily living activities. Patients usually undergo rehabilitation therapy with medical personnel for a long time after the traumatic event. In most cases, they use off-the-shelf medical devices. However, the shape of the upper limbs can differ a lot among people. A bespoke rehabilitative device could provide better comfort and usability, but the design process can be challenging. This work aims to present a digital workflow to generate a 3D virtual reconstruction of the patient's upper limb structure, to be used in the device design. Starting from a 3D scan acquisition of the patient's upper limb, the algorithm allows the creation of a polygonal mesh of the arm and the hand by a semi-automatic procedure. The algorithm uses neural networks' capability to automatically detect the upper limb's landmarks to localize the joints' coordinates. The joints' positions can be used to build a virtual skeleton for a 3D model of a human arm. The mesh of the model is subsequently wrapped around the scan of the real arm. The output consists in the 3D rigged model of the patient's upper limb with a manifold mesh that can be deformed using its virtual skeleton. The results have been assessed with patients who had sports injuries or strokes. The 3D deviations between the scan acquisition of the arm and the resulting model have been evaluated.

Keywords: 3D scan , 3D virtual reconstruction , automatic landmarks detection , neural network , upper limb rigged model

Design methods for sports engineering allow to improve the world around the athlete. In cycling, a sport device that can be useful to reduce and monitor the risk of injuries is a smart glove equipped with pressure sensors. The literature underlined how the current design methods lack the comprehensive consideration of sensors integration for force analysis at the handlebar. Furthermore, the majority of existing solutions is based on resistive pressure sensors. In this work, we present mainly two advancements with respect to the state-of-the-art: (1) user-centered design methodology for the glove development, which allows to take care about the main design parameters which involve the cyclist, namely her/his anthropometric characteristics and her/his sport gesture analysis (achieved by the pressure analysis on the handlebar) during classic grip position of cycling (i.e., top grip); (2) prototyping of custom-made capacitive pressure sensors instead of classic commercial resistive pressure sensors. The work involves the concept generation, the selection of the optimal concept through Kano and Quality of Function Development as well as the preliminary prototyping of one capacitive pressure sensor, realized using a fabrication process involving additive manufacturing techniques and silicon molding.

Keywords: capacitive sensors , human body scanning , injury risk , user-centered design

Additive Manufacturing (AM) is currently making the relevance of lattice structure solutions increasing, allowing the achievement of high performance/mass ratio, where performance stands for energy absorption, stiffness, and/or insulation. This paper undertakes lattice structure for lightweight design of a horse saddletree. Saddletree is the backbone of a horse saddle, and it is composed of different components. In particular, the spring steel reinforcements inside the saddletree make it the heaviest part of the horse saddle, involving also multiple processes of manufacturing and manual assemblies. This paper aims to lightweight an existing saddletree with a Voronoi lattice solution, reducing several manual assemblies. From the methodological point of view, the lightweight design has been based on a multi-scale approach, carried out via nTopology (static FEA on the original bulk design, implicit geometrical lattice generation from FEA result maps and Boolean operation among lattice results and bulk design implicit model). The original bulk design has been digitally acquired and modeled through Reverse Engineering techniques, so that a specific customized solution may be improved. A final weight reduction of 76.5% is achieved, providing an example of how topological optimization techniques coupled with AM (in particular Powder Bed Fusion technology) may reduce assembly efforts

Keywords: FEA , Horse Saddletree , Reverse Engineering , Topological Optimization , Voronoi Lattice Structure

Coralligenous (C) include calcareous build-ups of biogenic origin, formed since the Holocene transgression. Peculiar columnar-shaped C outcrops were documented offshore Marzamemi village (SE Sicily, Ionian Sea), although the actual extension and distribution were not assessed. Project ‘CRESCIBLUREEF' produced a new, 17 km2 high-resolution bathymetric map, leading to good knowledge about their extent in this area. C bioconstructions are largely distributed along two depth ranges 36–42 m and 86–102 m water depth. By coupling the documented uplift rate in this region and the Holocene sea-level curve, we were able to interpret the distribution of C outcrops over terraces. However, additional investigation is required to understand: (1) the role of the inherited continental shelf landscape, in creating a favorable substrate for the settlement and growth of C habitats during the Holocene, and (2) the extent to which C bioconstructions can impact the evolution of present-day continental shelf landforms and landscapes.

Keywords: biogeomorphology , Calcareous build-ups , Mediterranean sea , sea-level changes , seascape , submarine geomorphology

Medical simulation tools have become increasingly popular in recent years for planning complex and non-routine surgeries. This applies also to autologous ear reconstruction, a procedure that is performed when patients have a complete or partial lack of the outer ear. On the basis of the contralateral ear, the physician sculpts a portion of costal cartilage that is then placed subcutaneously in the auricular region. Simulation tools can help the physician to familiarize with the specific geometries and shapes of the ear to be reconstructed. Making simulation tools requires the 3D acquisition of the ear, which can be done through optical scanners or diagnostic images (CT scan). This work focused on the development of a non-invasive, low-cost scanner for the acquisition of the outer ear. To this end, Intel RealSense D405 cameras were chosen, and a dedicated structure for the acquisition of ear anatomy was designed and manufactured, coupled with management software. The design of the scanner leveraged tests made with the Blender software for the optimization of the position and number of devices, while ensuring complete ear acquisition. Tests allowed the validation of the instrument both qualitatively, indicating the satisfaction of the medical staff in using the scanner, and quantitatively, measuring the deviation of the acquisition from a reference model obtained with professional scanners.

Keywords: 3D Ear Acquisition , CAD Modelling , Optical Scanner , Reverse Engineering

The 3D reconstruction of upper limb anatomy plays a significant role in many biomedical fields such as ergonomics, motion rehabilitation, and prosthesis design. In the last few years, the technical advancement of consumer-grade depth cameras has supported the development of portable and low-cost optical 3D body scanners for healthcare applications. The real-time scanning of human body parts, however, still represents a complex task due to the non-stationary nature of the scanning target. This issue imposes that the scanning time must be reduced as much as possible to minimize scanning artifacts. In this regard, depth cameras can capture geometrical information at video frame rates, thus guaranteeing fast acquisition times. Furthermore, the simultaneous use of multiple sensors would minimize undercut geometries, which impair the 3D reconstruction's completeness. In this work, a portable 3D optical scanner has been developed by rigidly assembling three Intel® RealSense™ D415 depth cameras on a lightweight circular frame. The three sensors are mutually calibrated, by using a 3D printed calibration specimen, to simultaneously align acquisitions from the three different camera viewpoints for each scanner pose. The system's effectiveness has been assessed by acquiring the geometry of both a plaster hand and a human hand and comparing the results with those obtained by a high-end stationary structured light scanner. The developed system represents a low-cost handheld alternative to existing body scanners for collecting and storing 3D anatomical data, which can be used in the design process of bespoke medical devices.

Keywords: 3D optical scanning , D415 Intel® RealSense™ , Depth-camera , Upper Limb Reconstruction

The Marine Strategy Framework Directive (MSFD, 2008/56/EC) was adopted to achieve a Good Environmental Status (GES) in the EU's marine waters and to protect resources and ecosystem services, including the deep-sea waters and seafloor. The deep sea (below 200 m) is the largest biome on Earth, and its biodiversity plays a key role, despite being strongly threatened by several anthropogenic stressors, potentially affecting some ecosystem functions. Among the main deep-sea structuring species, the habitat-forming cold-water corals (CWCs) are known to form Vulnerable Marine Ecosystems (VMEs). In the Mediterranean Sea, in the last two decades, a significant effort has been devoted to unveiling the distribution, extension and ecological role of scleractinian CWCs (Madrepora oculata and Desmophyllum pertusum), but quantitative data on their conservation status are very limited. Because of their ecological importance and vulnerability, Italy has extended the implementation of the MSFD to the deep sea, carrying out specific monitoring programmes on these scleractinian CWCs. In this regard, this study established, for the first time, an extensive standardized baseline for national monitoring programmes focusing on two recently discovered upper bathyal areas dominated by scleractinian CWCs (Dohrn Canyon and Corsica Channel). The goal was to evaluate the ecological status of the bathyal biogenic reefs using traditional diversity and impact variables as well as the innovative photogrammetry tool. In both areas, the investigations have increased the knowledge about the extent of the habitat and new CWC assemblages in good health conditions were discovered. The pressure extent is limited with respect to the total extent of the CWC habitat, accounting for approximately 32% and 63% of the fishing-related items entangled on structuring species. The photogrammetric approach showed a deviation of about 33% in the measurement of the population size structures. Moreover, the use of a standardized operative protocol has been proposed to obtain reliable, coherent, and comparable data for future monitoring activities. This approach improved scientific knowledge for the two studied areas and it is pivotal in defining long-term monitoring activities useful to assess the effectiveness of specific protection measures, for these VMEs

Keywords: Cold-water corals , Fishing impact , Marine strategy framework directive (MSDF) , Mediterranean sea , Photogrammetry , ROV-Imaging

In this work, the authors aim at developing a reliable and fast methodology to evaluate the wear evolution in tire starting from a complete optical 3D scanning. Starting from a data cloud, a semi-automatic methodology was implemented in MATLAB to extract mean tread radial profiles in correspondence of the desired angular position of the tire. These profiles could be numerically evaluated to establish the presence of irregular wear and the characteristic parameter of the groove depth. The reliability and the robustness of this methodology was firstly tested by applying it to several synthetic case studies modeled in CATIA V5®, where ovalization and presence of defects were also simulated. The groove depth was determined with an error lower than 1% for the ideal model, while the introduction of ovalization and defects leaded to an error of 2.6% in the worst condition. In a second time, the methodology has been successfully applied to experimental measurements carried out in two different wear life of the tire, allowing the tracking of the wear phenomena through the evaluation of the progressive lowering of tread radial profiles.

Keywords: 3D scanning , discrete models , tire wear evaluation , tread profile

The following scientific paper aims to analyze in detail the methodology for reverse engineering of a racing motorcycle connecting rod. The objective is to start with a product available on the market as a spare part, reconstruct its CAD model with a high standard of accuracy, then proceed with lightening modifications to arrive at a new, improved design. The innovative aspect of the procedure lies in the fact that in order to ensure accuracy on the order of a tenth of a millimeter during reconstruction, it was decided to use a FARO articulated arm laser to scan the component's outer surface. By taking advantage of appropriate redesign CAD software (Geomagic Design X), a reconstruction can proceed within the high standard of accuracy imposed. In conclusion, the modifications made through material removal allow an improvement in product efficiency, ensuring high performance.

Keywords: CAD modelling , conrod , high-precision modeling , redesign , reverse engineering

The experimental evaluation of welding-induced distortion is a topic of great interest to both the scientific and industrial communities. With the aim of addressing a specific need in an industrial context, this paper investigates the capabilities of a stereo–Digital Image Correlation (stereo–DIC) system to measure the weld-induced distortion of the front-plate of a bogie train bolster subassembly. Currently, the deviation from planarity of this surface is measured at less than five points using a CMM in the post-weld cooled state. An additional machining process is then used to bring the surface within the tolerance required to join the welded assembly to the train body through a threaded flange. The paper shows that DIC can provide accurate full-field distortion and strain maps over the entire 588 mm × 308 mm surface of the front plate. The distinct strength of DIC over the currently used inspection technique is its ability to provide highly spatially dense data that are unaffected by rigid body motion. This can be advantageous in terms of saving time in the post-weld inspection and reducing errors in the finishing process. In addition, DIC capabilities revealed important information that was not available from the CMM, such as the full-surface map of the initial deviation of the plate from its nominal geometry and its asymmetric deformation after welding. Finally, the full-field nature of the experimental data obtained allows for seamless integration with FE thermo-mechanical simulations for numerical model validation, stress calculation, and optimization of geometry and technological processes.

Keywords: digital image correlation , full-field distortion and strain map , traction frame , welding-induced distortion

Developing an automatic process for the segmentation and dimensional characterization of high-semantic level features from a ceramic find is an essential prerequisite for obtaining faster, reproducible, and more accurate measurements than the manual approach. These measurements are essential for analyzing, interpreting, and classifying the archaeological pottery, comparing and analyzing similarities, identifying the presence of standard attributes in the ceramics recovered from a specific archaeological site, or studying ancient manufacturing technologies. This paper proposes a new methodology for the recognition and dimensional measurement of a specific class of geometric features starting from high-density tessellated models acquired by 3D scanners, the Constant-Radius Sweeping Features (CRSFs). The recognition process is performed based on a fuzzy algorithm, which aggregates similar adjacent nodes, according to values of appropriate membership functions, into a single geometric feature. CRSFs are frequently seen in ancient artifacts as convex traces on the ceramic surface, such as plastic and molded reliefs, or concave features, such as engravings, graffiti, working signs, and impressions/stampings. Although they are frequently characterized, from a geometric point of view, by free-form surfaces, CRSFs may also be axially symmetrical geometry: this occurs quite often in archaeological pottery in correspondence with rims, bases, or external walls. In the proposed experimentation, the new methodology is applied to three fragments belonging to the same ceramic vessel and sharing a part of its rim. The results show that the algorithmic implementation of rules for CRSF recognition and measurement enables the automation of the entire process, from feature segmentation to the evaluation of the relevant characteristic dimensions, with the benefit of obtaining more robust and precise measurements than those performed manually. Furthermore, in some circumstances, the methodology proposed here allows for assessing dimensional attributes that would otherwise be impossible to evaluate by conventional methods: this is the case of CRSF not attributable to analytical geometric types, as frequently occurs in archaeological ceramics in the form of decorations, grooves, and processing marks.

Keywords: Computer methods in archaeology , Dimensional features for cultural heritage , Fuzzy logic , Geometric feature recognition

Background and objective: The ability to accomplish a consistent restoration of a missing or deformed anatomical area is a fundamental step for defining a custom implant, especially in the maxillofacial and cranial reconstruction where the aesthetical aspect is crucial for a successful surgical outcome. At the same time, this task is also the most difficult, time-consuming, and complicated across the whole reconstruction process. This is mostly due to the high geometric complexity of the anatomical structures, insufficient references, and significant interindividual anatomical heterogeneity. Numerous solutions, specifically for the neurocranium, have been put forward in the scientific literature to address the reconstruction issue, but none of them has yet been persuasive enough to guarantee an easily automatable approach with a consistent shape reconstruction. Methods: This work aims to present a novel reconstruction method (named HyM3D) for the automatic restoration of the exocranial surface by ensuring both the symmetry of the resulting skull and the continuity between the reconstructive patch and the surrounding bone. To achieve this goal, the strengths of the Template-based methods are exploited to provide knowledge of the missing or deformed region and to guide a subsequent Surface Interpolation-based algorithm. HyM3D is an improved version of a methodology presented by the authors in a previous publication for the restoration of unilateral defects. Differently from the first version, the novel procedure applies to all kinds of cranial defects, whether they are unilateral or not. Results: The presented method has been tested on several test cases, both synthetic and real, and the results show that it is reliable and trustworthy, providing a consistent outcome with no user intervention even when dealing with complex defects. Conclusions: HyM3D method proved to be a valid alternative to the existing approaches for the digital reconstruction of a defective cranial vault; furthermore, with respect to the current alternatives, it demands less user interaction since the method is landmarks-independent and does not require any patch adaptation.

Keywords: Bioinformatics , Computed aided design , Cranioplasty , Statistical shape model , Surface Interpolation

An area of interest in orthopaedics is the development of efficient customized neck orthoses, considered that pathologies which affect the neck area are widespread. Advanced acquisition and modelling approaches combined with Additive Manufacturing (AM) can potentially provide customized orthoses with improved performance and complexity. However, in the design of these devices, besides functional and structural requirements, benefit and comfort of the patient should be a main concern, in particular, at the early stage of design during the acquisition of the body's part, and while using the printed orthosis. In this paper, a scanning system with three sensors was developed which allows a fast, about 5 s, and accurate acquisition of the neck area with minimum discomfort for the patient. A neck orthosis with a ventilation pattern obtained by Topology Optimization (TO), lightened by about 35%, was also established. In fact, a main role for comfort is played by the ventilation pattern which contributes both to lightness and breathability. Its structural and comfort performance was evaluated in comparison with an orthosis with a ventilation pattern configured by Voronoi cells. Structural assessment was carried out by means of finite element analysis under main loading conditions. An evaluation of neck temperatures in relation to wearing 3D printed prototypes, manufactured with Hemp Bio-Plastic® filament, was finally conducted by means of a thermal imaging camera. TO orthosis prototype showed a better performance regarding thermal comfort, with a maximum increase of neck temperature less than 1 °C, which makes the proposed configuration very promising for user's comfort.

Keywords: Additive manufacturing , CAD , Orthosis modelling , Reverse engineering , Thermal comfort , Topology optimization

Although reality-based models are widely used to describe the geometric surfaces of an entity in a digital space, a systematic and universally recognised treatment of issues such as accuracy is lacking. The topic is certainly complex as this analysis should involve not only shape approximation but also other attributes (e.g., colour). Wanting to limit ourselves to geometry alone, this work proposes solutions for assessing the quality of photogrammetric models, differentiating them according to possible scenarios: sometimes, homologous models obtained using different techniques and technologies are available. In these cases, a comparison between digital reconstructions can serve to effectively quantify accuracy; more often, no terms of comparison are available, and one is forced to derive indicators from the same photogrammetric process to describe quality. We propose for this scenario a statistical analysis on the covariance matrix of the estimated coordinates for the tie points. The main goal is to provide a range of possible approaches to the conscious management of survey data.

Keywords: Accuracy assessment , Coordinate covariance matrix , Hausdorff distance , Tolerance intervals

[No abstract available]

3D digitisation is essential to enhance knowledge and conservation processes for Cultural Heritage (CH). However, movable heritage collected in museums, e.g., archeological finds, statues, coins, and musical instruments, often consists of highly reflective surfaces and/or featureless textures. The aim of this work is to stress the Structure from Motion Dense MultiView Reconstruction (SfM-DMVR) of objects, whose optical properties are challenging to this image-based technique. To improve the results obtained by SfM-DMVR standard acquisition workflow, this study exploited the potential of combining Noise Function Pattern (NFP) projection and light Cross Polarization (CP). Moreover, High Dynamic Range (HDR) image reconstruction was tested on images acquired according to different CP angles. The SfM-DMVR of a texture-less shiny ceramic object was then compared to the one obtained by a structured light triangulation scanner, the most reliable tool for such surfaces, but unfortunately quite expensive. The advantages and limitations of the presented method are discussed.

Keywords: 3D reconstruction , Cross polarization , Featureless surface , HDR blending , Pattern projection , Reflective surface

The fracture resistance of multilayer zirconia crowns has recently been proven to be improved by using lithium millable disilicate glass–ceramic blocks (D'Addazio in Materials, 2020). Accordingly, the framework and the ceramic coating are designed and milled using a CAD-CAM technology and the two separated prosthetic components are then manually assembled by the dental technician and glued with the fusion of a glass–ceramic material. It is essential, during the CAD phase, to design a gap between the framework and the decorative veneer that will later be filled by the fused ceramic.Since the act of gluing the two parts is manually performed by the dental technician, we aim at investigating the operator influence on the final gap with respect to the designed gap. For this purpose, an original geometrical investigation method was developed to enable the 3D digital analysis of the whole fusion interface. During the CAD design stage, two technicians input a different setting for the gap between the two components. The framework and veneering structure were designed, the milled components were produced, and the zirconia framework was sintered, then the two CAD-on prosthetic components were scanned before and after their fusion/crystallization to analyze the physical internal gap. The results show that manual assembly cancels out any effect of the precision settings adopted during CAD-CAM design of the components, as well as any benefit expected from machining on a CNC milling machine, thus requiring, as a last step, manually retouching the prosthesis to correctly fit in the mouth.

Keywords: Bioengineering , CAD modeling , Dentistry , Interactive design , Reverse engineering

Background: Microtia is a congenital anomaly of the ear. We present an innovative technique using a 3D personalized framework that could simplify and standardize the sculpting phase, thanks to reverse engineering and additive manufacturing techniques. Methods: Three-dimensional models were realized by T3Ddy, a joint laboratory between the department of industrial engineering and Meyer Children's Hospital. Data were obtained retrospectively and included patient demographics, primary diagnosis, side of the affected ear, microtia classification, surgical time, length of hospitalization, type of skin approach and framework, complications, aesthetic results, and level of satisfaction using specific questionnaires. Data are reported as median and IQR. Results: A total of 17 children (female gender: four) underwent auricular reconstruction surgery with autologous cartilage in our center, between 2019 and 2022. Median age at surgery was 14 years [interquartile range (IQR), 13-17], and the median hospitalization length was 5 days (IQR, 3-5). Median surgical time was 420 minutes (IQR, 406-452). Complications occurred in four patients out of 19 procedures, with a complication rate of 21%. Aesthetic results were satisfactory in all cases. Conclusions: The three-dimensional models allow for an intuitive and precise approach. Having developed specific models for each component of the framework, we aimed to improve the aesthetic result and simplify the surgical intervention, guaranteeing a standardized yet personalized experience for each patient. The interprofessional partnership is fundamental to achieving this result.