3D scanning

The geometrical performance of Additive Manufactured (AM) parts, particularly the influence of printing orientation on geometrical properties, is an open topic of investigation. The task of understanding geometry deviations across different printing orientations can be laborious, involving a multitude of experiments and the measurement of deviation fields. This study introduces a three-stage comprehensive methodology to address this issue. (i) An experimental investigation is conducted at varying printing orientation and the printed parts are captured by laser scanning; (ii) an automatic 3-2-1 alignment procedure of the scanned geometries is implemented, accurately replicating real positioning procedures; and (iii), Reduced-Order Modelling (ROM) is applied for the parametric mapping of deviation fields to orientation angles, creating a surrogate model of the non-nominal parts. Demonstrated with PET-G specimens, this approach can be applied to various geometries. Thanks to the surrogate model, the deviation field for any orientation can be obtained in real-time. As a result, the efficiency and accuracy of the AM process can be improved by reducing setup and scanning time when investigating different printing configurations. This allows manufacturers to focus more on part design and optimization, potentially leading to significant advancements in AM.

Keywords: 3-2-1 alignment , Additive manufacturing , Geometric deviations , Printing orientation , Reduced-order modelling

In recent years, maritime industries have focused their attention on hydrofoils as one of the main technologies for the development of eco-sustainable solutions in the field of boating. The aim of the current research was to analyze the front wing of a Kohlkida class hydrofoil and to describe the methodology employed for the reconstruction of the 2-D airfoils by means of photogrammetry. Considering the limitations of the photogrammetry methods, some sections were extracted from the model. The airfoils were properly scaled and first compared with the model obtained by means of a laser scanner. Under the operating condition of the hydrofoil and with the use of Reynolds-averaged Navier–Stokes simulations, the behavior of the airfoils was simulated, allowing us to verify how the geometric differences due to the photogrammetry approach affect the fluid dynamics, in comparison to the model obtained from laser scanning. The proposed methodology led to a geometry reconstruction with adequate accuracy for the identification of both the characteristic curves for the lift and drag coefficients with a maximum error of 6% in the angle-of-attack range investigated in the study, also highlighting fluid dynamics problems that characterize this type of airfoils with a flat bottom and a knife-sharp leading edge.

Keywords: Computational fluid dynamics (CFD) , hydrofoil design and modeling , laser scanning , measurements , photogrammetry , reverse engineering

Background and objective: Despite the availability of several commercial solutions for predicting the soft tissue outcomes of maxillofacial surgeries, none have proven sufficiently reliable for routine clinical use. This study proposes a 3D methodology for predicting soft tissue displacement following maxillofacial surgery without relying on mechanical modeling, unlike most existing approaches. Methods: Pre- and post-operative Cone Beam Computed Tomography scans of patients with class III malocclusion were collected. Tailored image processing and volume reconstruction techniques were applied to semi-automatically generate 3D soft tissue models. Cephalometric landmarks were identified to perform a geometrical similarity analysis among patients with the same malocclusion class undergoing the same surgical procedure. Vectorial displacement maps were generated to capture the soft tissue changes from pre- to post-operative and were then applied to the pre-operative of test patients to predict soft tissue outcomes. Euclidean distances were calculated between predicted and real post-operative positions, and the Wilcoxon signed-rank test was conducted to assess statistical differences between predicted and real landmark coordinates. Results: Error maps indicated that approximately 70 % of predicted facial points had errors below 2.5 mm, while around 10 % ranged between 2.5 mm and 3 mm. Statistically significant differences (p < 0.05) were observed only for the gonion and cheilion. Conclusion:. The findings support the validity of the geometrical similarity analysis and the vectorial displacement map approach. The simplicity and promising accuracy of the proposed method encourage further investigations across different surgical procedures. Additionally, integrating this methodology into surgical planning could offer a viable alternative to commercial solutions.

Keywords: 3D soft tissue prediction , Dental malocclusion , Displacement vectorial map , Orthognathic surgery , Soft tissue displacement

This study investigates the structural behavior of the monoblock crankcase of a commercial common rail diesel engine, with a specific focus on the displacements of main bearing housings under realistic operating conditions. A detailed reverse engineering approach was employed to reconstruct the crankcase geometry, followed by finite element simulations of critical load cases derived from combustion pressure and inertial dynamics. The mechanical design criteria of crankcases and hydrodynamic bearing systems are reviewed to define acceptable tolerance ranges and deformation limits. Stress and displacement analyses were conducted across multiple engine operating scenarios to identify critical regions and evaluate the structural integrity of the engine block. Results indicate that the most significant bearing misalignments occur at central supports, suggesting potential areas for reinforcement or design improvement.

Keywords: Crankcase , Displacement , Finite element analysis , Manufacturing , Reverse engineering , Structural design

Real-time rendering is increasingly used in augmented and virtual reality (AR/VR), interactive design, and product visualisation, where materials must prioritise efficiency and consistency rather than the extreme accuracy required in offline rendering. In parallel, the growing demand for personalised and customised products has created a need for digital materials that can be generated in-house without relying on expensive commercial systems. To address these requirements, this paper presents a low-cost digitisation workflow based on photometric stereo. The system integrates a custom-built scanner with cross-polarised illumination, automated multi-light image acquisition, a dual-stage colour calibration process, and a node-based reconstruction pipeline that produces albedo and normal maps. A reproducible evaluation methodology is also introduced, combining perceptual colour-difference analysis using the CIEDE2000 ((Formula presented.)) metric with angular-error assessment of normal maps on known-geometry samples. By openly providing the workflow, bill of materials, and implementation details, this work delivers a practical and replicable solution for reliable material capture in real-time rendering and product customisation scenarios.

Keywords: digitalisation workflow , material scanner , photometric stereo , real-time rendering , texture evaluation

This work presents a generative design algorithm for the semi-automatic reconstruction of sweepable surfaces from point clouds obtained through three-dimensional scanning. The proposed algorithm enables, starting from a 3D acquisition dataset, the correct automatic orientation of the mesh, the selection of a suitable cutting edge, and the specification of the number of transversal sections for an effective 3D model reconstruction. Additionally, it suggests a maximum number of points to be used for reconstructing the sectional curves. The mesh reconstruction is performed through a lofting operation, resulting in a non-uniform rational B-spline (NURBS) surface. The algorithm has been applied to a case study involving the front wing surface of a foil from the Olympic class iQFoil, which has recently garnered significant attention from researchers in the field of performance analysis. The obtained reconstructed surface exhibits very low deviation values when compared to the original mesh.

Keywords: 3D reconstruction , generative algorithm , innovative methods , iQFoil windsurfing foil

The shape and tuning of bells provide archaeologists with valuable insights into their historical origins and casting methods. Unfortunately, the availability of fully preserved medieval and Renaissance bells is limited worldwide due to the remelting of many specimens following fractures, wear, or traumatic events such as earthquakes. The original geometry is therefore reconstructed by archaeologists by examining uncovered external mould during excavations. However, determining the symmetry axis and interpreting the profiles of small fragments is not trivial, and fragments are not always easily reassembled along their fracture surfaces. To solve this issue, this paper presents a computer-based method that enables the automated virtual reconstruction of ancient bells from their external mould fragments. The approach performs geometric and differential analysis of discrete models obtained from 3D scans of the fragments, facilitating the retrieval of a consistent 3D shape, thereby aiding in the preservation and understanding of historical relics.

This paper introduces a novel triangular encoding technique specifically designed for identifying geometric correspondences in structured light three-dimensional (3D) imaging. The proposed method, based on a hybrid approach between pseudo-dot arrays and M-arrays, overcomes limitations of existing encoding strategies by using a triangular pattern that directly encodes information in a 2D grid. The paper presents the theoretical framework for the encoding, a pseudo-algorithm for its application to 2D images, and a discussion of the algorithm's capabilities and limitations. An interesting potential of using this pattern is its ability to reduce the post-processing time required to generate 3D models, as it can inherently determine the connectivity of the vertices in the projected mesh. The proposed triangular encoding approach is shown to be particularly effective for dynamic 3D scene reconstruction and for applications requiring robust information encoding, such as QR codes. Additionally, the paper outlines the potential for future work in developing a decoding strategy and further refining the encoding system using multiple states, such as RGB colors.

Keywords: 3D imaging , combinatorial geometry , encoding techniques , pattern recognition , structured light

This study presents a comparative analysis of two portable 3D scanning technologies, structured light and LiDAR, applied to the reverse engineering of fiberglass boat molds. Key aspects such as acquisition speed, data completeness, resolution, feature detectability, and operational usability were evaluated. Due to the absence of a CAD reference, a relative geometric deviation analysis between the overlapping regions of the scans was performed. Results indicate that while the LiDAR-based scanner offers rapid and comprehensive coverage suitable for large-scale geometry capture, the structured light scanner provides higher resolution in localized areas but requires more careful setup and markers for effective scanning. The complementary nature of these technologies suggests potential advantages in hybrid scanning strategies for marine manufacturing applications.

Keywords: 3D scans , LiDAR scanning , quality control , reverse engineering , structured light scanning

Biophilic design, which emphasizes integrating natural elements into built environments, is increasingly valued for its positive impact on workplace well-being and productivity. This study investigates how extended reality (XR) technologies can support biophilic design by incorporating digital representations of plants into immersive virtual and augmented workspaces. Central to this research is the evaluation of methods for generating realistic and adaptable digital plants suitable for XR integration, focusing on balancing visual quality, flexibility, and usability. Photogrammetry, a technique that creates detailed 3D models by combining photographs from multiple angles, is explored for its potential to quickly produce high-resolution digital plant assets. Despite its advantages, photogrammetry struggles with rendering fine details, such as delicate branches and leaves, limiting its effectiveness in XR settings. To address these shortcomings, the study compares photogrammetry with procedural modeling — a rapidly evolving approach supported by several tools. Procedural modeling offers enhanced precision, control, and adaptability, enabling dynamic, real-time modifications and interactions in virtual environments. The research highlights how technological innovations can advance biophilic design by enabling the seamless integration of natural elements into digital workspaces. Through comparative analysis, the paper identifies optimal strategies for creating immersive, well-being-focused environments that align with the principles of biophilic design. Ultimately, this study illustrates the potential of XR to transform workplace design by merging nature-inspired elements with cutting-edge digital tools, fostering environments that support both human and organizational productivity.

Keywords: Biophilic design , Digital plants , Extended reality (XR) , Photogrammetry , Procedural modeling

The integration of Human Body Digitization Technologies (HBDTs) into the fashion industry presents a transformative approach to personalize garment design and production while addressing sustainability challenges. This study investigates the feasibility, accuracy, and effectiveness of various measurement techniques, including traditional manual methods, 3D body scanning, and smartphone applications, to capture anthropometric data. A mixed-methods approach was employed for a pilot study involving 15 participants to assess the technical reliability of HBDTs in comparison to established garment manufacturing standards. Findings indicate that while traditional measuring techniques suffer from significant variability and inaccuracy, 3D scanning technologies demonstrate a higher degree of reliability, yielding measurements suitable for on-demand garment production. However, smartphone applications, while convenient, often lack precision and completeness in capturing essential dimensions for garment fitting. The study reveals that the successful adoption of HBDTs requires a comprehensive understanding of the digital anthropometric pipeline, necessitating interdisciplinary skills among fashion practitioners. Key challenges include operator errors, digital avatar optimization, and software limitations. Despite this, HBDTs show strong potential to improve garment fit, reduce waste, and support inclusivity. The study underscores the need for further research and highlights the value of advanced measurement methods for a more human-centric and sustainable fashion industry.

Keywords: 3D body scanning , Body sizing , Digital avatar , Fashion design , Sustainability

Autologous ear reconstruction is a surgical procedure which aims to restore the anatomy of the outer ear whenever there are malformations due to congenital defects (microtia) or as a result of trauma and burns. Reconstruction involves the cutting, carving, and modeling of a portion of costal cartilage harvested from the patient. The aesthetic results of the surgery are highly dependent on the manual skill of the surgeon, which therefore needs a wide range of surgical experience. Appropriate simulation and training tools are essential to acquire adequate familiarity with the procedure without compromising the patient's aesthetic appearance. In such a context, the present work aims to create replicas of the costal cartilage that allow a realistic simulation of the surgery, thus taking into account important characteristics of the cartilage tissue such as the behavior to cut and suture, hardness, etc. The problem is approached with well-established Additive Manufacturing and Reverse Engineering techniques, which are increasingly being used in the medical field, addressing both the problem of identifying the most suitable materials and the possibility of providing medical personnel with simple interactive procedures for the fabrication of multilayer replicas, without the need to turn to expert CAD modelers.

Keywords: CAD modeling , Costal cartilage mold , Ear reconstruction , Medical simulation

Implementing an alternative reality for Metaverse implies modeling optimized digital content to guarantee real-time interaction and high-quality rendering. Even if 3D reconstruction based on 3D scanning techniques provides a good replica of real objects, the output files are challenging to use in this application. On the other hand, manually developed optimized 3D models require much time and effort. This aspect becomes crucial in scenarios including thousands of 3D models with which humans should interact. This paper proposes a method to automate the 3D modeling process of items whose shapes can be classified according to predefined geometrical categories. The dataset for this study relates to products, which present a wide variety of shapes but are attributable to just a few formal archetypes. In the proposed pipeline, metric orthographic images of the object to be digitally reproduced are analyzed by Convolutional Neural Networks (CNN)s. Subsequently, the same images are analyzed with Computer-Vision (CV) algorithms to extrapolate the characteristic dimensions related to the assigned archetypes. The method has been tested on different items, and the results proved the effectiveness of the whole approach in terms of correct archetypes recognition, parameter extraction, and creation of the 3D model, which are comparable with digitized 3D models with high-quality scanning tools but much lighter in model size.

Keywords: 3D Object Database , Artificial Intelligence , Automatic 3D Modeling , Computer Vision , Convolutional Neural Network , Process Optimization

This study aims to evaluate the advantages and criticalities of applying additive manufacturing to produce climbing holds replicating real rocky surfaces. A sample of a rocky surface has been reproduced with a budget-friendly 3D scanner exploiting structured light and made in additive manufacturing. The methodology is designed to build a high-fidelity replica of the rocky surface using only minor geometry modifications to convert a 2D triangulated surface into a 3D watertight model optimised for additive manufacturing. In addition, the research uses a novel design and uncertainty estimation approach. The proposed methodology proved capable of replicating a rocky sample with sub-millimetre accuracy, which is more realistic than conventional screw-on plastic holds currently used in climbing gyms. The advantages can be addressed in terms of customisation, manufacturing cost and time reduction that could lead to real outdoor climbing experiences in indoor environments by coupling additive manufacturing techniques and reverse engineering (RE). However, operating the scanner in a rocky environment and the considerable size of the climbing routes suggest that further research is needed to extend the proposed methodology to real case studies. Further analysis should focus on selecting the best material and additive manufacturing technology to produce structural components for climbing environments.

Keywords: 3D scanning , Additive manufacturing , Climbing holds , Fused deposition modelling , Reverse engineering , Uncertainty quantification

Galleries, libraries, archives, and museums are nowadays striving to implement innovative approaches to adequately use and distribute the wealth of knowledge found in cultural heritage. A range of technologies can be used to enhance the viewing experience for visitors and boost the expertise of museologists, art historians, scholars, and audience members. The present work aims to provide an overview of current methods and most pertinent studies addressing the use of the innovative technologies for enhancing the fruition of artifacts in traditional museums in an effort to improve the public experience and education. For all the technologies discussed, the paper focuses on the main results obtained in literature and on their possible implementation in the museal context. The overview demonstrates the liveliness of the world of research in the field of technologies for the digital development of museums and how many technologies commonly used in industry are increasingly finding their way into the cultural sphere.

Keywords: 2.5D , 3D acquisition , Additive manufacturing , Artificial intelligence , Augmented reality , Linguistic tools , Museums , Storytelling

In the last couple of decades, the research on 3D facial expression recognition has been fostered by the creation of tailored databases containing prototypical expressions of different individuals and by the advances in cost effective acquisition technologies. Though, most of the currently available databases consist of exaggerated facial expressions, due to the imitation principle which they rely on. This makes these databases only partially employable for real world applications such as human-computer interaction for smart products and environments, health, and industry 4.0, as algorithms learn on these ‘inflated' data which do not respond to ecological validity requirements. In this work, we present two novel 2D + 3D spontaneous facial expression databases of young adults with different geographical origin, in which emotions have been evoked thanks to affective images of the acknowledged IAPS and GAPED databases, and verified with participants' self-reports. To the best of our knowledge, these are the first three-dimensional facial databases with emotions elicited by validated affective stimuli.

Keywords: 3D facial expression , Affective database , Ecological validity , Facial expression recognition , Human-computer interaction , Spontaneous expressions

Manipulating patient data acquired by Computer tomography (CT), e.g., anatomical shape and geometry, as well as studying the biomedical devices used in patient care, is certainly of remarkable importance. Here, Medical Re- verse Engineering (MRE) and Rapid Prototyping (RP) play a key role in the 3D models reconstruction of patient anatomy, that can be exploit to make patient- specific, custom-made devices. The inherent variability of the human anatomy can be a problem, which is why the concept of custom-made devices is men- tioned. In this field, MRE exploits the computational tools provided by Statistical Shape Modelling (SSM) and Principal Component Analysis (PCA) to achieve computer modelling of 3D data from real models. The PCA is a statistical tool for reducing the number of variables in a population, while the SSM enables the development of an infinite digital population of a given anatomy. This paper aims to show the potential of SSM in the field of the MRE. The study will focus on the pathological lumbar spine. Here, SSM provides new pathological geometries of the lumbar spine, which can be extrapolated and used to produce customized biomedical devices for that given pathological deformation, as well as to perform Finite Element (FE) simulations. Therefore, utilising SSM can bring an addi- tional edge to MRE, due to the infinite population of CAD models of patient anatomy, which can be useful in the medical industry, as already pointed out.

Keywords: Lumbar spine , Medical Reverse Engineering , Patient-specific , Statistical Shape Modelling

The Reverse Total Shoulder Arthroplasty (RTSA) is a complex surgical procedure also due to the difficulty in correctly positioning all the components of the prosthesis. Malpositioning of the prosthesis, in fact, can lead to various complications such as scapular notching, early mobilization, instability and reducing of the range of movement (ROM). Preoperative planning with 3D imaging and patient specific instruments can be very useful tools to help surgeon in selecting the optimal position of implant components. Aim of this work is to develop a procedure based on a fully parametric CAD system that simulates the shoulder joint to identify the optimal positioning of the humeral and glenoid components of the prosthesis. In particular, the proposed system allows to find the optimal cutting angles of the humerus head and the glenoid cavity so to best fit the patient's bone structure and the prosthesis components and, consequently, to improve the range of movement. The system allows to create, in a semi-automatic way, CAD assembly models composed of the patient shoulder bones and different reverse shoulder prostheses. For each assembly different positions of the components of the prosthesis can be evaluated and various scenarios of movements can be simulated. In this way it is possible to identify the optimal positioning of the prosthesis for each patient in the preoperative stage. The proposed procedure has been tested with two types of prosthesis and two patients. Obtained results demonstrated that an optimal positioning of prosthesis an improve ROM up to 27%.

Keywords: CAD , Preoperative planning , Reverse engineering , Reverse total shoulder arthroplasty

The widespread and diversified use of portable devices with high magnification power at relatively low-cost, i.e., the so-called USB digital microscopes, has revealed the possibility of employing their photographic output in Structure from Motion processes for sub-millimetric digitisation. However, USB microscopes, born for two-dimensional inspection – if used without specific accessories, designed ad-hoc for the photogrammetric capture phase – can pose some difficulties for the surveyor in managing capture operations. Thus, this study suggests prototyping a low-cost, complete, and portable mounting compatible with the most common USB microscopes for image scanning. This system makes it possible to use portable USB microscopes for three-dimensional modelling at a low-cost, as it is easy to replicate both in terms of construction and the materials used. Therefore, through the interaction of several skills, the work shows how the photogrammetric process can also be made accessible to devices that were not initially designed for such application, paving the way for new paths in representation engineering research.

Keywords: Additive Manufacturing , Fast Survey , Structure from Motion

Autologous ear reconstruction is a surgical procedure performed in the case of defects of the outer ear in which the malformed anatomy is reconstructed with autologous cartilage tissue and often involves the use of surgical guides modelled from a digital reconstruction of the ear anatomy. To obtain such three-dimensional anatomy, traditional imaging methods, which are expensive and invasive, can be replaced by professional 3D scanners or low-cost commercial devices. In this context, this paper focuses on the evaluation of two devices for the acquisition of the outer ear, the Intel® RealSense D405™ (stereo camera) and the TrueDepth camera of the iPhone® 13 (structured light camera), proposing a comparison based on four parameters: accuracy, precision, deviation range and point-to-point distance, in order to assess their usability in the medical field, and in particular in the context of autologous ear reconstruction. The results show that, despite significantly different handling of the raw data, the performance of the two devices is comparable: average accuracy is 0.76 mm for the D405 and 0.95 mm for the iPhone 13, average precision is 0.071 mm for the D405 and 0.065 mm for the iPhone 13, average range of deviation is 3.12 mm for the D405 and 3.64 mm for the iPhone 13.

Keywords: 3D scanning , Accuracy assessment , Ear reconstruction , RealSense D405 , TrueDepth camera