3D scanning

Background and Objective: The paper presents a novel procedure based on 3D scanning and 3D modelling to automatically assess linear and volumetric measurements of an arm and to be further applied to patients affected by post breast cancer lymphedema. The aim is the creation of a virtual platform easily usable by medical personnel to get more objective evaluations during the lymphedema treatment. Methods: The procedure is based on the 3D scanning of the arm using the Occipital Structure Sensor and an ad-hoc developed application, named Lym 3DLab. Lym 3DLab emulates the traditional measurement methods, which consist in taking manual circumference measurements or using the water displacement method. These measurements are also used to design the compression stockings, the typical orthopaedic device used for lymphedema treatment. A validation test has been performed to compare the measurements computed by Lym 3DLab with both water displacement and manual circumference measurements. Eight volunteers have been involved who are not affected by lymphedema. Furthermore, a specific usability test has been performed to evaluate the 3D scanning procedure by involving four physiotherapists. Results: The comparison between the volumes has highlighted how all the 3D acquired models have their volumes inside a range of acceptability. This range has been defined by considering the sensitivity error of the tape measure used to measure the water displacement. The comparison between the perimeters of cross sections computed with Lym 3DLab and the circumference measurements has shown results that are very accurate with an average difference of 2 mm. The measure errors have been considered negligible by the medical personnel who have evaluated the proposed procedure more accurate than the traditional ones. The test with physiotherapists has shown a high level of usability of the whole virtual environment, but the 3D scanning procedure requires an appropriate training of the personnel to make the 3D acquisition as fast and efficient as possible. Conclusions: The achieved results and the physiotherapists' feedback allow planning a future test with patients affected by lymphedema in collaboration with the hospital. A further test has been planned to use the computed measurements to design orthopaedic compression stockings.

Keywords: 3D scanning , Arm Volume , Circumference Measurement , Lym 3DLab , Lymphedema , Occipital Structure Sensor

The protection of artistic and cultural heritage is a major challenge due to its peculiarities and its exposure to significant natural hazards. Several methodologies exist to assess the condition of artistic heritage and to protect it from exceptional actions. Moreover, novel digital technologies offer many solutions able to deliver a digital replica of artifacts of interest, so that a reduction in the uncertainties in the analysis models can be achieved. A rational approach to the preservation and protection of artistic heritage is based on traditional approaches supported and integrated by novel technologies, so that qualitative and quantitative indicators of the current condition of artistic heritage can be defined and validated in an interdisciplinary framework. The present paper reports the results of an approach to the maintenance and preservation of art objects housed in a museum complex based on a comprehensive digital path towards a Historical Digital Twin (HDT). A workflow aimed at estimating the stress regime and the dynamic properties of two sculptures, based on the detailed three-dimensional model resulting from a laser scanner survey, is illustrated and dis-cussed. The results highlight the great advantages resulting from the integration of traditional and novel procedures in the field of conservation of artistic assets.

Keywords: 3D simulation , Conservation , Cultural heritage , Digital twin , Laser scanning , Maintenance

This paper considers the fitting of a CAD template model to tessellated data as strategy to implement a reverse engineering process that aims at the reconstruction of a parametric associative CAD model. The reconstruction methodology, called Template-Based CAD Reconstruction (TCRT), has been presented and fully discussed in a previous paper Buonamici et al. (J Comput Des Eng 5:145–159, 2018). The present paper focuses on the study of a fast and robust strategy to perform the fitting of the Template CAD Model to reference data. The study explores how different optimization strategies and evaluation metrics can affect a parametric CAD-fitting methodology. Two different optimization algorithms (PSO and GA) and three formulations of the objective function are tested to find the most effective combination. Reconstruction test cases are presented and discussed in the text.

Keywords: CAD reconstruction , CAD template , Fitting , Genetic Algorithm , Particle Swarm Optimization , Reverse engineering

Home-based recovery is gradually being used to reduce health-care costs; however, with a shorter stay in the hospital, the risk of growing adverse clinical outcomes exists, mainly due to the lack of motivation in the patient and on the difficulties in performing a strict control by the doctors. This is particularly true for patients who went under knee arthroplasty or total knee replacement who should strictly follow the effective recovery protocols delivered by the doctors. The development of tools for measuring the functional recovery of the operated joint is therefore deemed crucial both for the patient to feel motivated in performing the right number of exercises, and for the doctor that can follow him/her up remotely. One of the most recognized methods for assessing the correctness of a series of recovery exercises, is to monitor the pose of the patient in real-time so as to evaluate its posture in his range of motion. Accordingly, in this paper a novel hybrid approach to 3D human pose estimation is proposed. A first estimation of 2D body pose of the patient in the scene is given, then the depth information coming from the RGB-D sensor is exploited to estimate the joints 3D coordinates. The proposed algorithm proved to overcome the main limitation of using a pure 3D skeleton tracking algorithm during physiotherapy rehabilitation.

Keywords: 3D , Body tracking , Data fusion , Joints estimation , RGB-D camera

Autologous ear reconstruction is the preferred treatment in case of partial or total absence of the external ear. The surgery can be very challenging to perform and the aesthetic result highly dependent on the surgeon's “artistic skills”. In this context a preoperative planning and simulation phase based on the patient's specific anatomy may result crucial for the surgical outcome. In this work, starting from a case study, the elements necessary for an effective simulation are identified and a strategy for their interactive design and customization is devised with a perspective of a semi-automatization of the procedure.

Keywords: Additive manufacturing , Autologous ear reconstruction , Microtia , Preoperative planning , Reverse engineering

The article discusses the design of an acquisition system for the 3D surface of human arms. The system is composed by a 3D optical scanner implementing stereoscopic depth sensors and by an acquisition software responsible for the processing of the raw data. The 3D data acquired by the scanner is used as starting point for the manufacturing of custom-made 3D printed casts. Specifically, the article discusses the choices made in the development of an improved version of an existing system presented in [1] and presents the results achieved by the devised system.

Keywords: 3D printing , 3D scanning , Arm scanner , Body scanner , Orthoses

In this research, we describe a computer-aided approach to improve the reconstruction method of decorum in architectural surfaces and sculpture. The effects of withdrawal caused by catalysis of mold in silicone was evaluated and simulated by a NURBS-based solid modelling. A tolerance analysis model was developed to predict manufacturing precision levels. In particular, differential increment along three dimensions was performed considering different volume distributions. The methodology was validated by experimental data obtained during the coffered ceiling restoration of Teatro Massimo Vittorio Emanuele in Palermo. The proposed methodology allowed the reconstruction of decorations or fragments of decoration with high accuracy.

Keywords: Geometric dimensioning and tolerancing , Restoration techniques , Reverse engineering , Silicon mold , Withdrawal

In the last decades, the popularity of video games has been increasing thanks to their unique ability to engage their audience and create empathy. Among them, serious games have additional purposes besides entertainment, such as learning and behaviour change. Serious games, in fact, have been successfully applied to different fields, including education, health, tourism, and cultural heritage. In this context, the paper describes a novel serious game developed for increasing awareness and promoting the Underwater Cultural Heritage (UCH). In particular, the paper focuses on the Dive in the Past Serious Game which allows users to simulate a virtual dive into the Mediterranean Sea to explore accurate and life-sized 3D reconstructions of underwater archaeological sites. The purpose of the game is twofold: to engage diver and non-diver tourists into a virtual interactive exploration of underwater sites through digital storytelling and challenges; to increase awareness and knowledge on Mediterranean UCH. This work has been carried out in the context of the MeDryDive project, an EU co-funded under the COSME Programme, which aims to create personalized dry dive experiences for the promotion of Mediterranean UCH sites as distinctive tourism destinations.

Keywords: 3D reconstruction , Mediterranean Sea , Serious game , Underwater archaeology , Underwater Cultural Heritage

RGB-D cameras are employed in several research fields and application scenarios. Choosing the most appropriate sensor has been made more difficult by the increasing offer of available products. Due to the novelty of RGB-D technologies, there was a lack of tools to measure and compare performances of this type of sensor from a metrological perspective. The recent ISO 10360-13:2021 represents the most advanced international standard regulating metrological characterization of coordinate measuring systems. Part 13, specifically, considers 3D optical sensors. This paper applies the methodology of ISO 10360-13 for the characterization and comparison of three RGB-D cameras produced by Intel® RealSense™ (D415, D455, L515) in the close range (100–1500 mm). ISO 10360-13 procedures, which focus on metrological performances, are integrated with additional tests to evaluate systematic errors (acquisition of flat objects, 3D reconstruction of objects). The present paper proposes an off-the-shelf comparison which considers the performance of the sensors throughout their acquisition volume. Results have exposed the strengths and weaknesses of each device. The D415 device showed better reconstruction quality on tests strictly related to the short range. The L515 device performed better on systematic depth errors; finally, the D455 device achieved better results on tests related to the standard.

Keywords: Active stereo , Depth camera , Device characterization , ISO 10360-13 , LiDAR , Performance comparison , RealSense D415 , RealSense D455 , RealSense L515 , Reverse engineering

Cranioplasty is a procedure performed to repair defects in the human skull bone by surgically reconstructing the shape and function of the cranium. Several complications, both intraoperative and postoperative, can affect the procedure's outcome (e.g., inaccuracies of the reconstructed shape, infections, ulcer, necrosis). Although the design of additive manufactured implants in a preoperative stage has improved the general quality of cranioplasties, potential complications remain significant, especially in the presence of critical skin tissue conditions. In this paper, an innovative procedure to improve the chances of a positive outcome when facing critical conditions in a cranioplasty is described. The proposed approach relies on a structured planning phase articulated in a series of digital analyses and physical simulations performed on personalized medical devices that guide the surgeon in defining surgical cuts and designing the implant. The ultimate goal is to improve the chances of a positive outcome and a fast recovery for the patient. The procedure, described in extenso in the paper, was positively tested on a cranioplasty case study, which presented high risk factors.

Keywords: Additive manufacturing , Cranioplasty , Patient-specific implant , Skull reconstruction

The objective of this study is to establish a new methodology for the metrological characterization of interactive multi-camera systems. In the case of 3D system highly adapted to specific needs the accuracy evaluation cannot be performed using standard state-of-the-art techniques. To this end, the metrological characterization techniques used in the literature were investigated in order to define a new methodology that can be adjusted to each device by making the appropriate modifications. The proposed strategy is adopted for the metrological characterization of a new interactive multi-camera system for the acquisition of the arm.

Keywords: Accuracy assessment , Device characterization , Multi-camera system , Optical device , VDI/VDE normative

Since 3D printing was developed, it became the most promising technique to speed up prototyping in a wide variety of areas across the industry. Rapid prototyping allows the medical industry to customize the surgery procedures, thus predicting its result. Biomedical applications made by medical grade elastic thermoplastic polyurethane (TPU); a non-traditional plastic material which allows to obtain additional benefits in rapid 3D prototyping because of its flexibility and anti-bacteriological capabilities. The aim of this study is to assess the efficacy of TPU polymer, FDM objects sourced from CT scanned 3D surfaces for helping surgeons in preoperative planning and training for increasing environment perception, that is, geometry and feeling of the tissues, whilst performing standard procedures that require complex techniques and equipment. A research was performed to assess the physical and qualitative characteristics of TPU 3D developed objects, by developing a proper SWOT analysis against PLA, a widely used, and cost-effective option in FDM industry. Therefore, giving a proposition opposite to other known modern medical planning techniques and bringing out the benefits of the application of TPU-sourced, FDM parts on professional medical training. As a result, PLA is a reliable, wide-available process whilst TPU's flexible capabilities improves realism in 3D printed parts. Surgical planning and training with rapid prototyping, would improve accurate medical prototyping for customized-procedures, by reducing surgery times, unnecessary tissue perforations and fewer healing complications; providing experience that other FDM materials like PLA cannot be reached.

Keywords: 3D Printing , 3D Scanner , QFD , Surgical Training , TPU

Autologous ear reconstruction is the preferred treatment in case of partial or total absence of the patient external ear. This kind of surgery can be really challenging since precise replication of complex three-dimensional structure of the ear is crucial to provide the patients with aesthetically consistent reconstructed anatomy. Therefore, the results strongly depends on the “artistic skills” of the surgeon who is in charge to carry out a three-dimensional sculpture, which resembles the shape of a normal ear. In this context, the definition of a preoperative planning and simulation process based on the patient's specific anatomy may help the surgeon in speeding up the ear reconstruction process and, at the same time, to obtain better results, thus allowing a superior surgical outcome. In the present work the main required features for performing an effective simulation of the ear reconstruction are identified and a strategy for their interactive design and customization is devised with the perspective of a semi-automatization of the procedure. In detail, the paper provides a framework which start from the acquisition of 3D data from both a healthy ear of the patient (or, if not available e.g. due to bilateral microtia of the ear of one of his parents or from a template) and of costal cartilage. Acquired 3D data are properly processed to define the anatomical elements of the ear and to find, using nesting-based algorithms, the costal cartilage portions to be used for carving the ear itself. Finally, 3D printing is used to create a mockup of the ear elements and a prototype of the ear to be reconstructed is created. Validated on a test case, the devised procedure demonstrate its effectiveness.

Keywords: Additive manufacturing , Autologous ear reconstruction , Microtia , Preoperative planning , Reverse engineering

The increasing availability of 3D anatomical models obtained from diagnostic images exploiting Reverse Engineering techniques allows the application of statistical analysis in the quantitative investigation of anatomical shapes variability. Statistical Shape Models are a well-established method for representing such variability, especially for complex forms like the anatomical ones. Not by chance, these models are widely used for medical applications, such as guiding segmentation of the diagnostic image and virtual reconstruction of incomplete anatomic region. The application of a statistical analysis on a set of shapes representing the same anatomical region essentially requires that shapes must be in correspondence, i.e. constituted by the same number of points in corresponding position. This work aims to compare two established algorithms, namely a modified version of the Iterative Closest Point and the non-rigid version of the Coherent Point Drift, to solve the correspondences' problem in the construction of a Statistical Shape Model of the human cranium. The comparison is carried out on the models using the standard evaluation criteria: Generalization, Specificity and Compactness. The modified version of the Iterative Closest Point delivers a better Statistical Shape Model in terms of Generalization and Specificity, but not for Compactness, than the Coherent Point Drift-based model.

Keywords: Computer-Aided Technologies , Correspondences' problem , Reverse Engineering , Statistical Shape Analysis , Statistical Shape Model

The growing interest in the auricular anatomy is due to two different strands of research: 1) in the medical field it is associated with autologous ear reconstruction, a surgery adopted following trauma or congenital malformations; 2) in surveillance and law enforcement the ear is used for human detection and recognition. Alternative systems of ear analysis can be differentiated for the type of input data (two-dimensional, three-dimensional or both), for the type of acquisition tools (3D scanner, photographs, video surveillance, etc.) and finally for the adopted algorithms. Although the segmentation and recognition of the ear from the face is a widely discussed topic in literature, the detection and recognition of individual anatomical elements has not yet been studied in depth. To this end, this work lays the foundation for the identification of the auricular elements through image processing algorithms. The proposed algorithm automatically identifies the contours of the main anatomical elements by processing depth map images. The algorithm was tested qualitatively and quantitatively on a dataset composed of 150 ears. The qualitative evaluation was performed with the collaboration of medical staff and the quantitative tests were performed using manually annotated ground truth data.

Keywords: Depth map , Ear biometrics , Ear dataset , Ear reconstruction , Ear segmentation , Microtia

The restrictions associated with the current SARS-Cov-2 pandemic are having a major impact on nearly all human activities and interactions; among these, the didactic and education field certainly has a prominent place. In the case of either complete lockdown or reduced accessibility to facilities and classrooms, the participation of students was severely limited for safety reasons. In particular, laboratory activities, already compromised by a large number of students of some classes, suffered from the restrictions, thus making it difficult to guarantee the possibility of live operating on instruments for the execution of measurements of different quantities of interest. To overcome the considered problem, this article proposes the use of enabling technologies of the Internet of Things and the fourth industrial revolution to allow students to achieve correct and complete training in laboratory activities. To this aim, remotely controlled instruments are used and displayed in augmented reality on consumer devices, such as mobile phones, tablets, or personal computers. The continuous availability of access to the instruments along with the realism in their representation and use ensures a positive and effective involvement of the students.

Keywords: Augmented reality (AR) , enabling technologies , Industry 40 , Internet of Things , remote laboratories , remote measurements , reverse engineering

The detection of the symmetry axis from discrete axially symmetric surfaces is an interesting topic, which is transversal to various fields: from geometric inspection to reverse engineering, archeology, etc. In the literature, several approaches have been proposed for estimating the axis from high-density triangular models of surfaces acquired by three-dimensional (3D) scanning. The axis evaluation from discrete models is, in fact, a very complex task to accomplish, due to several factors that inevitably influence the quality of the estimation and the accuracy of the measurements and evaluations depending on it. The underlying principle of each one of these approaches takes advantage of a specific property of axially symmetric surfaces. No investigations, however, have been carried out so far in order to support in the selection of the most suitable algorithms for applications aimed at automatic geometric inspection. In this regard, ISO standards currently do not provide indications on how to perform the axis detection in the case of generic axially symmetric surfaces, limiting themselves to addressing the issue only in the case of cylindrical or conical surfaces. This paper first provides an overview of the approaches that can be used for geometric inspection purposes; then, it applies them to various case studies involving one or more generic axially symmetric surfaces, functionally important and for which the axis must be detected since necessary for geometric inspection. The aim is to compare, therefore, the performances of the various methodologies by trying to highlight the circumstances in which these ones may fail. Since this investigation requires a reference (i.e. the knowledge of the true axis), the methodologies have been applied to discrete models suitably extracted from CAD surfaces.

Keywords: axially symmetric surfaces , Axis of symmetry , geometric inspection , geometrical dimensioning and tolerancing , high-density triangular models

Traditionally, duplicating handmade artefacts was done primarily by moulds. To obtain multiples of the casts, the artisan laid out a layer of clay over the mould and pressed on it strongly to make sure of thorough contact. The moulds found by excavation show wear due to compression and deterioration over time. They often disintegrate and are unusable. Consequently, understanding and studying the images they contain is only possible when the moulds are re-useable for casts which, to date, are carried out in restoration laboratories by traditional techniques. It should be noted that apart from the casts' shrinking, moulds are also subject to altered sizes and morphologies after extraction from the archetype and therefore at the end of the production line the cast image is all the more blurred due to a loss of detail. This study describes a multidisciplinary approach applied to two clay moulds from classical antiquity that differ in size and shape, and the casts they produce using traditional techniques. Using Reverse Engineering (RE) by 3D laser scanning, a computer-based method was applied to study their morphometric relationship only obtainable in a virtual environment without compromising the integrity of the physical models. Furthermore, the digitalised moulds have provided virtual casts without significant size alterations for the aims of this work, making them ‘ideal' casts. These last casts were then converted by Rapid Prototyping (RP) into physical prototypes which have negligible geometric errors for making multiple replicas for educational or exhibition purposes. In archaeology, this method offers researchers the opportunity to study and acquire morphological data which the moulds themselves cannot, nor can their casts. So, it is possible to go back in time to images which match their archetypes even without their casts. More detailed knowledge about the form of an art object is important for its study, conservation and how it was produced. So, ancient clay moulds are studied particularly in investigating methods of mass production, their social value and the degree of specialisation of those ancient societies.

Keywords: 3D laser scanning , 3D technology in archaeology , Ancient mould , Cultural heritage survey , Morphometric analysis , Virtual model

Personalized medicine is an effective tool to improve the quality of rehabilitation and treatment for patients with disabilities. This study deals with the development of a low-cost hand scanner for the acquisition of anthropometric measures. The data acquired by the scanner is used, thanks to the developed procedure, to tailor the dimensions of a hand exoskeleton. The exoskeleton is used for assistive and rehabilitation purposes.

Keywords: 3D scanning , Anthropometric measurements , Depth sensor , Hand model , Hand scanner

Marine animal forests are benthic communities dominated by sessile suspension feeders (such as sponges, corals, and bivalves) able to generate three-dimensional (3D) frameworks with high structural complexity. The biodiversity and functioning of marine animal forests are strictly related to their 3D complexity. The present paper aims at providing new perspectives in underwater optical surveys. Starting from the current gaps in data collection and analysis that critically limit the study and conservation of marine animal forests, we discuss the main technological and methodological needs for the investigation of their 3D structural complexity at different spatial and temporal scales. Despite recent technological advances, it seems that several issues in data acquisition and processing need to be solved, to properly map the different benthic habitats in which marine animal forests are present, their health status and to measure structural complexity. Proper precision and accuracy should be chosen and assured in relation to the biological and ecological processes investigated. Besides, standardized methods and protocols are strictly necessary to meet the FAIR (findability, accessibility, interoperability, and reusability) data principles for the stewardship of habitat mapping and biodiversity, biomass, and growth data.

Keywords: 3D monitoring , biodiversity , biogenic reefs conservation , semantic segmentation , underwater photogrammetry