3D scanning

Currently, the growing need for highly customized implants has become one of the key aspects to increase the life expectancy and reduce time and costs for prolonged hospitalizations due to premature failures of implanted prostheses. According to the literature, several technological solutions are considered suitable to achieve the necessary geometrical complexity, from the conventional subtractive approaches to the more innovative additive solutions. In the case of cranial prostheses, which must guarantee a very good fitting of the region surrounding the implant in order to minimize micromotions and reduce infections, the need of a product characterized by high geometrical complexity combined with both strength and limited weight, has pushed the research towards the adoption of manufacturing processes able to improve the product's quality but being fast and flexible enough. The attention has been thus focused in this paper on sheet metal forming processes and, namely on the Single Point Incremental Forming (SPIF) and the Superplastic Forming (SPF). In particular, the complete procedure to design and produce titanium cranial prostheses for in vivo tests is described: starting from Digital Imaging and COmmunications in Medicine (DICOM) images of the ovine animal, the design was conducted and the production process simulated to evaluate the process parameters and the production set up. The forming characteristics of the prostheses were finally evaluated in terms of thickness distributions and part's geometry. The effectiveness of the proposed methodology has been finally assessed through the implantation of the manufactured prostheses in sheep.

Keywords: Custom prosthesis , In vivo tests , Single point incremental forming , Superplastic forming , Ti‐6Al‐4V ELI

Burn injuries requires post-accident medical treatment. However, the treatment of burns does not end with first aid because scarred skin must be managed for many years, and in some circumstances, for life. The methods used to evaluate the state of a burn scar based, for instance, on Patient and Observer Scar Assessment Scale or similar ones, often lacks in univocally assessing the scarred skin's state of health. As a result, the primary aim of this research is to design and build a prototype that can support the doctor during scar assessment, and eventually therapy, by providing objective information on the state of the lesion, particularly the value of skin pliability. The developed tool is based on the depressomassage treatment probe named LPG, currently used to treat burn scars in a number of hospitals. It consists of a non-invasive massage technique using a mechanical device to suction and mobilize scar tissue and is used as a post-operative treatment to speed up the healing process to make the mark of the scar less visible. The prototype is specifically designed to be manufactured using Additive Manufacturing and was validated comparing its performances against the ones of a certified instrument (i.e., the Romer Absolute ARM with RS1 probe). Validation was carried out by designing and developing a tool to put the RS1 probe in the same measurement conditions of the new prototype probe. Tests performed to assess the performance of the devised prototype show that the probe developed in this work is able to provide measurements with a sufficient degree of accuracy (maximum error ±0.1 mm) to be adopted for a reliable estimation of the pliability value in a hospital environment.

Keywords: 3D measurement , additive manufacturing (3D printing) , burn scars , pliability , reverse engineering

Close-range photogrammetry (C-RP) is a widespread and efficient technology to obtain digital models of physical objects. Typical limitations as sharped geometry, shiny surface finishing and light conditions can be overcome by using high-end equipment, which results in increased costs and requires specific skills in human operators. This paper aims to investigate whether a low-cost and simplified approach to C-RP makes it suitable for the 3D acquisition of bodywork components and similar free-form artefacts, as an affordable alternative to 3D scanning in fields where a lower value of accuracy is required. Hence, two commercial C-RP software were used to 3D capture handcrafted car body panels and compare the C-RP models using a 3D scan as a reference within an inspection software. Two case studies are considered: a 1:5 scale model of the front bonnet of a Ferrari 250 Testa Rossa from 1958 and a head lamp housing of a Ferrari 275 GTB from 1962. Considering the complexity of double curvature surfaces and the reflection due to material and surface treatment, both these artefacts require some pre-processing operations and an adequate set-up to perform image acquisition. These case studies represent a relevant application for the field of classic vehicle restoration, where C-RP could be a promising technique to support panel beaters and craftsmen during rebuilt operations of masks and bodywork spare parts of high-end historic cars.

Keywords: 3D capturing , 3D digital model , car body panel , Classic vehicle restoration , Close-range photogrammetry , Geometric inspection

Laboratory experiences have proved to be a key moment of the educational path in most of the so-called Sciences, Technology, Engineering and Mathematics (STEM) subjects. Having the opportunity of practicing on actual experiments about the theoretical knowledge achieved during the classroom lectures is a fundamental step from a didactic point of view. However, lab activities could be forbidden in the presence of tests characterized by safety issues, thus limiting students' cultural growth; this is particularly true for physics experiments involving radioactive materials, sources of dangerous radiations. To face the considered problems, the authors propose hereinafter a mixed-reality solution involving augmented reality (AR) at students-side and actual instrumentation at laboratory-side. It is worth noting that the proposed solution can be applied for any type of experiment involving the remote control of measurement instruments and generic risk conditions (physical, chemical or biological). As for the considered case study on gamma radiation measurements, an ad-hoc AR application along with a microcontroller-based prototype allows students, located in a safe classroom, to (i) control distance and orientation of a remote actual detector with respect to different radioactive sources and (ii) retrieve and display on their smartphones the corresponding energy spectrum. The communication between classroom equipment and remote laboratory is carried out by means of enabling technologies typical of Internet of Things paradigm, thus making it possible a straightforward integration of the measurement results in cloud environment as dashboard, storage or processing.

Keywords: Augmented reality , Mixed-reality education , MQTT protocol , Physics experiments , Radiation measurements , Remote laboratory , Reverse engineering

The digital image correlation (DIC) was used in this paper to obtain full-field measurements of a target vibrating at a frequency higher than the maximum cameras' frame rate. The down-sampling technique was implemented to compensate for the cameras' moderate frame rate, thus getting an accurate displacement acquisition even at 6.5 kHz. Two innovative methods to support the DIC application were introduced. The use of fringe projection (or structured light), initially applied on the sample at rest, reduced the effort and time required for the stereo matching task's solution and improved this setting's accuracy and reliability. Additionally, a new time-domain image filtering was proposed and tested to improve the quality of the obtained DIC maps. In combination with the down-sampling, the effect of this filtering technique was tested in this work at (approx.) 2500 and 6500 Hz by measuring the response of a bladed disk to sinusoidal excitation. Evidence of improved results was observed for both frequencies for amplitudes in the range of 10 µm.

Keywords: Bladed disk , Digital image correlation , Down-sampling approach , Low-speed camera , Reverse engineering , Vibration measurement

In this work the performances of three different techniques for 3D scanning have been investigated. In particular two commercial tools (smartphone camera and iPad Pro LiDAR) and a structured light scanner (Go!SCAN 50) have been used for the analysis. First, two different subjects have been scanned with the three different techniques and the obtained 3D model were analysed in order to evaluate the respective reconstruction accuracy. A case study involving a child was then considered, with the main aim of providing useful information on performances of scanning techniques for clinical applications, where boundary conditions are often challenging (i.e., non-collaborative patient). Finally, a full procedure for the 3D reconstruction of a human shape is proposed, in order to setup a helpful workflow for clinical applications.

Keywords: 3D printing , 3D scanning techniques , customised orthopaedic brace , low-cost technology , multimodal approach , non-collaborative patient , non-contact measurement

Underwater photogrammetry provides a means of generating high-resolution products such as dense point clouds, 3D models, and orthomosaics with centimetric scale resolutions. Underwater photogrammetric models can be used to monitor the growth and expansion of benthic communities, including the assessment of the conservation status of seagrass beds and their change over time (time lapse micro-bathymetry) with OBIA classifications (Object-Based Image Analysis). However, one of the most complex aspects of underwater photogrammetry is the accuracy of the 3D models for both the horizontal and vertical components used to estimate the surfaces and volumes of biomass. In this study, a photogrammetry-based micro-bathymetry approach was applied to monitor Posidonia oceanica restoration actions. A procedure for rectifying both the horizontal and vertical elevation data was developed using soundings from high-resolution multibeam bathymetry. Furthermore, a 3D trilateration technique was also tested to collect Ground Control Points (GCPs) together with reference scale bars, both used to estimate the accuracy of the models and orthomosaics. The root mean square error (RMSE) value obtained for the horizontal planimetric measurements was 0.05 m, while the RMSE value for the depth was 0.11 m. Underwater photogrammetry, if properly applied, can provide very high-resolution and accurate models for monitoring seagrass restoration actions for ecological recovery and can be useful for other research purposes in geological and environmental monitoring.

Keywords: bathymetry , habitat restoration , monitoring , multibeam , Posidonia oceanica , Structure from Motion , underwater photogrammetry

Burn scar treatment is a difficult subject to address since the improper therapy can have a significant impact on people's quality of life. The evaluation of medical therapy over time should be based on objective measurement of the severity of burn scars and their progression. Unfortunately, most clinical assessments of scars are still reliant on physicians' subjective exams of patients. A profitable method to overcome the limitations of subjective assessment could be to leverage 3D scanning technologies. These could be used to retrieve the surface topology of burns. Accordingly, the goal of this study is to provide an objective approach for analysing the surface topology of burn scars using 3D scanning and roughness-based evaluation. In particular, two types of ISO-compliant profile and surface filters (Gaussian and Wavelet) derived from the analysis of roughness in the mechanical sector are implemented to discriminate form from roughness of scars. Once retrieved, the roughness surface is processed to derive a set of statistical parameters describing the scar surface topology. Three case studies were used to derive these parameters (a synthetic surface, an ostrich-skin surface and a set of scars). After the surface's roughness was determined, a comparison between healthy and unhealthy skin could be established. The devised methods prove their effectiveness in correctly retrieving the main surface characteristics of a burn scar. Therefore, by using the proposed method it will be possible to evaluate the effectiveness of medical therapy by comparing the healthy and scarred skin of a single subject.

Keywords: 3D scanning , Burn scars , Gaussian filtering , Roughness , Wavelet filtering

In the last years, the precision and personalized medicine is pushing the biomedical research efforts towards the direction of implant surgery requiring only 1-step approach: this goal has been achieved after the introduction of resorbable implants. The resorbable prosthetic support is indicated for temporary prosthetic applications, such as bone fractures fixation, or all those conditions usually treated with metal implants then removed with a second surgery, just after the healing of the bone defect. Biodegradable, bioactive and customizable implants for the treatment of bone fractures, both efficient in bearing the functional loads, and showing good biocompatibility and degradation properties matching the bone tissue healing, are still lacking. These premises have led to consider Magnesium (Mg) and its alloys as very promising candidates for the development of temporary, resorbable implants. However, the very high corrosion rate of Mg is the main problem, not yet solved. The material needs to be properly treated/coated, as well as manufactured, in order to design the most suitable duration of the temporary prosthesis permanence in situ. An innovative and interdisciplinary approach has been developed within the M.Era-Net ISIDE project and it is here briefly detailed with a special focus on the highlighted application fields.

Keywords: customade prostesis , Mg alloys , Reabsorbable implants

Small-scale experimental tests were carried out by a bi-disc machine to reproduce the phenomena occurring in shoe-braked railway wheels. Wheel specimens of three different steels were subjected first to a braking step against cast iron brake-block specimens in full sliding condition, then to a running step against a rail steel in rolling-sliding condition. To monitor the damage occurring at the wheel specimen surface, a vision system, based on a high-speed camera acquiring the surface images during the tests, was implemented. An image analysis procedure was elaborated to evaluate the surface state by means of quantitative synthetic indexes. The correlation of such indexes with the damage was validated by means of comparison with the subsurface state, obtained by optical microscope observation of cut specimens. Finally, the synthetic indexes were used to analyse the evolution of the damage on a long-duration test, proving to be effective as a non-destructive damage monitoring tool.

Keywords: Bi-disc tests , Damage analysis , Railway wheel steels , Shoe-braking , Vision system

The “San Pietro al Monte Abbey project: a virtual tour for everyone” consists in the construction of a high-tech station that allows visitors with mobility limitations to be virtually accompanied by a guide to the Benedictine abbey of San Pietro al Monte along the ancient access route that can only be reached on foot with trekking equipment. The room with the virtual instrumentation is located in the Casa del Pellegrino in Civate (Lecco, Italy). It is a museum structure-based located in a media reception building. From its entrance, it is possible to see the final destination. The virtual tour preserves the dialogue between the environment, the monument, and the ‘virtual pilgrim'. By also acting as an information database, it enhances the use of the basilica of San Pietro al Monte even for visitors equipped with tablets who reach the building on foot. The virtual tour application has been developed with Unity3D. The interactive application has different virtual scenes with photos, 360 ∘ videos, an external digital twin of the abbey, and some interesting internal digital twins of the most important monuments inside the abbey.

Keywords: Digital twin , Photogrammetry , Virtual tour

At Annone di Brianza (Italy) in the Church of St. George, it is possible to admire the “ANCONA DELLA PASSIONE" (altarpiece of the Passion), an altarpiece painted and gilded carved wood cabinets. The great altarpiece adorned the right side chapel of Saint John the Baptist, whose construction dates back to the first half of the century XVI at the behest of Annoni, one of the most authoritative families of Milan of the sixteenth and seventeenth century. Since 2019 the altarpiece has been protected inside a special room in order to avoid damage caused by the temperature and humidity. Access to this room is not allowed to people who visited the church. In order to allow the user to admire and explore each minimal detail of the polyptych altarpiece a totem has been designed and it's located just outside of the special room. The totem in fact is composed of a 32 in. touch screen with a PC embedded and the Virtual tour application. The Virtual tour application has been developed with Unity3D. The interactive application has different virtual scenes with photos, videos, an external digital twin of the polyptych with both, open and closed doors.

Keywords: Digital twin , Inclusive tour , Photogrammetry , Virtual tour , Visual impairment users

Intraoral three-dimensional scanning techniques could be used to improve dental practice, leading to an improved overall quality of the prosthetic devices and improved comfort for the patient. An accurate and precise intraoral scanner allows proper diagnosis, follow-up evaluation, and prosthesis application. The aim of this research is to evaluate the precision of an intraoral scanners (Medit i500, Medit Corp., Seoul, Korea), using open-source software in the digital workflow. The precision was compared through repetitions of the scanning process of the upper dental arch, following superimpositions in the whole 3D arch area. It was possible to display colorimetric maps for qualitative comparison, and the deviations of the values were classified as clinically acceptable. Within the limitation of this study, the clinically acceptable in vivo frequency of points' deviation, or the precision, was obtained in 98.8% ± 1.4%; therefore, the use of open-source software can be a viable option in the digital workflow, improving patient follow ups with the 3D model superimposition.

Keywords: conventional impression , digital impression , intraoral scan

In the Industry 4.0 scenario, additive manufacturing (AM) technologies play a fundamental role in the automotive field, even in more traditional sectors such as the restoration of vintage cars. Car manufacturers and restorers benefit from a digital production workflow to reproduce spare parts that are no longer available on the market, starting with original components, even if they are damaged. This review focuses on this market niche that, due to its growing importance in terms of applications and related industries, can be a significant demonstrator of future trends in the automotive supply chain. Through selected case studies and industrial applications, this study analyses the implications of AM from multiple perspectives. Firstly, various types of AM processes are used, although some are predominant due to their cost-effectiveness and, therefore, their better accessibility and wide diffusion. In some applications, AM is used as an intermediate process to develop production equipment (so-called rapid tooling), with further implications in the digitalisation of conventional primary technologies and the entire production process. Secondly, the additive process allows for on-demand, one-off, or small-batch production. Finally, the ever-growing variety of spare parts introduces new problems and challenges, generating constant opportunities to improve the finish and performance of parts, as well as the types of processes and materials, sometimes directly involving AM solution providers.

Keywords: classic cars , component reproduction , Industry 4.0 , original equipment manufacturer (OEM) , rapid tooling , replacement parts , restoration , reverse engineering

To compare the reference geometry approach to the best-fit (or superimposition) approach in the estimation of geometric accuracy relevant to the digital and the analog workflow to fabricate a complete denture. Starting from a model of an edentulous maxilla, the two measuring methodologies were tested to estimate the geometric accuracy of the intaglio surface of the complete dentures fabricated by CNC milling and injection molding. Eight areas of interest were defined at the intaglio surface of the denture base; a sensitivity analysis determined the minimum number of measuring points to calculate a reliable Δ ¯ error value. A repeatability analysis was performed to assess the consistency of this experimental reference geometry approach with respect to the clinic acceptable requirements. For the analog workflow, the comparison of the reference geometry results to the best-fit results showed a − 76 (post-dam) ÷ 169 µm (right flange) range of the Δ ¯ mean value for the reference geometry approach, to be compared to − 15 (left crest) ÷ 146 µm (right tuberosity) range for the best-fit approach. For the digital workflow, the same comparison showed a − 21 (left crest) ÷ 51 µm (left flange) range for the reference geometry approach, compared to a − 20 (left crest) ÷ 23 µm (left flange) for the best-fit approach. The best-fit approach results in an underestimation of mean Δ ¯ error values and their distribution over the entire prosthesis. The reference geometry approach correctly estimates error values while focusing on the identification of sources of errors in the manufacturing process.

Keywords: Accuracy , Best fit , CAD–CAM , Complete dentures , Digital manufacturing , RPS

The paper presents the development of a Virtual Reality application to perform dives in the Christoforos Shipwreck. The huge wreck lies in the Panormos Bay of the Skopelos island (Greece) at a depth of 45 meters. Based on a well-known methodology designed for ancient shipwrecks, the 3D reconstruction of the underwater site has been carried out by adjusting the workflow to survey modern shipwrecks. In particular, the methodology, based on photogrammetry, is capable to provide a highly detailed 3D reconstruction of the shipwreck in few dives, considering issues like working depth, elevations, and thin elements modelling. Moreover, the paper describes the optimization of the 3D model and the software to be executed in low-performance HMD devices. The resulting Virtual Reality (VR) application, realized for touristic purposes, recreates the exact ambient conditions inside and outside the water simulating the flora and fauna of the place, the coastline, allowing users to live a recreational and educational experience by virtual diving in the underwater site.

Keywords: 3D modeling , History , Image reconstruction , Ships , Three dimensional computer graphics

A wide range of materials has been considered to repair cranial defects. In the field of cranioplasty, poly(methyl methacrylate) (PMMA)-based bone cements and modifications through the inclusion of copper doped tricalcium phosphate (Cu-TCP) particles have been already investigated. On the other hand, aliphatic polyesters such as poly (e-caprolactone) (PCL) and polylactic acid (PLA) have been frequently investigated to make scaffolds for cranial bone regeneration. Accordingly, the aim of the current research was to design and fabricate customized hybrid devices for the repair of large cranial defects integrating the reverse engineering approach with additive manufacturing, The hybrid device consisted of a 3D additive manufactured polyester porous structures infiltrated with PMMA/Cu-TCP (97.5/2.5 w/w) bone cement. Temperature profiles were first evaluated for 3D hybrid devices (PCL/PMMA, PLA/PMMA, PCL/PMMA/Cu-TCP and PLA/PMMA/Cu-TCP). Peak temperatures recorded for hybrid PCL/PMMA and PCL/PMMA/Cu-TCP were significantly lower than those found for the PLA-based ones. Virtual and physical models of customized devices for large cranial defect were developed to assess the feasibility of the proposed technical solutions. A theoretical analysis was preliminarily performed on the entire head model trying to simulate severe impact conditions for people with the customized hybrid device (PCL/PMMA/Cu-TCP) (i.e., a rigid sphere impacting the implant region of the head). Results from finite element analysis (FEA) provided information on the different components of the model.

Keywords: Composite bone cement for cranioplasty , Design for additive manufacturing , Finite element analysis , Reverse engineering , Temperature profile analysis

Many industrial sectors face increasing production demands and the need to reduce costs, without compromising the quality. The use of robotics and automation has grown significantly in recent years, but versatile robotic manipulators are still not commonly used in small factories. Beside of the investments required to enable efficient and profitable use of robot technology, the efforts needed to program robots are only economically viable in case of large lot sizes. Generating robot programs for specific manufacturing tasks still relies on programming trajectory waypoints by hand. The use of virtual simulation software and the availability of the specimen digital models can facilitate robot programming. Nevertheless, in many cases, the virtual models are not available or there are excessive differences between virtual and real setups, leading to inaccurate robot programs and time-consuming manual corrections. Previous works have demonstrated the use of robot-manipulated optical sensors to map the geometry of samples. However, the use of simple user-defined robot paths, which are not optimized for a specific part geometry, typically causes some areas of the samples to not be mapped with the required level of accuracy or to not be sampled at all by the optical sensor. This work presents an autonomous framework to enable adaptive surface mapping, without any previous knowledge of the part geometry being transferred to the system. The novelty of this work lies in enabling the capability of mapping a part surface at the required level of sampling density, whilst minimizing the number of necessary view poses. Its development has also led to an efficient method of point cloud down-sampling and merging. The article gives an overview of the related work in the field, a detailed description of the proposed framework and a proof of its functionality through both simulated and experimental evidences.

Keywords: 3D reconstruction , Adaptive mapping , Inspection , Metrology , Robotics , View planning

The left ventricle (LV) constantly changes its shape and function as a response to patho-logical conditions, and this process is known as remodeling. In the presence of aortic stenosis (AS), the degenerative process is not limited to the aortic valve but also involves the remodeling of LV. Statistical shape analysis (SSA) offers a powerful tool for the visualization and quantification of the geometrical and functional patterns of any anatomic changes. In this paper, a SSA method was devel-oped to determine shape descriptors of the LV under different degrees of AS and thus to shed light on the mechanistic link between shape and function. A total of n = 86 patients underwent computed tomography (CT) for the evaluation of valvulopathy were segmented to obtain the LV surface and then were automatically aligned to a reference template by rigid registrations and transformations. Shape modes of the anatomical LV variation induced by the degree of AS were assessed by principal component analysis (PCA). The first shape mode represented nearly 50% of the total variance of LV shape in our patient population and was mainly associated to a spherical LV geometry. At Pearson's analysis, the first shape mode was positively correlated to both the end-diastolic volume (p < 0.01, R = 0.814) and end-systolic volume (p < 0.01, and R = 0.922), suggesting LV impairment in patients with severe AS. A predictive model built with PCA-related shape modes achieved better perfor-mance in stratifying the occurrence of adverse events with respect to a baseline model using clinical demographic data as risk predictors. This study demonstrated the potential of SSA approaches to detect the association of complex 3D shape features with functional LV parameters.

Keywords: Aortic valve stenosis , Left ventricle , Statistical shape analysis

The paper presents a method to develop Virtual Reality (VR) platforms based on serious games for the rehabilitation of severe memory loss. In particular, it is related to retrograde amnesia, a condition affecting patient's quality of life usually caused by brain stroke. Nowadays, the standard rehabilitation process consists in showing pictures of patient's familiar environments in order to recover the memory. Past research works have investigated the use of 3D scanners for the virtualization of real environment and virtual reality for the generation of more immersive interaction to design serious games for neurocognitive rehabilitation. Reached results highlighted a time-consuming development process to interface each new environment with the game logic specifically developed for the serious games. Furthermore, a complete VR platform must also consider the medical monitoring and the data management oriented to a more objective medical assessment. The proposed method allows the design of VR platforms based on patient-specific serious games for memory loss starting from the 3D scanning acquisition of familiar environments. The 3D acquisition is performed using the Occipital Structure Sensor and the Skanect application. A modular procedure has been designed to interface the virtual objects of each acquired environment with the modules of the game-logic developed with Unity. The immersive Virtual Reality is based on the use of the HTC Vive Pro head mounted display. Furthermore, the method permits to associate the patient-specific serious game to a set of software modules for the medical monitoring and the data management for the generation of reports useful for the evaluation. The solution has been evaluated by measuring the time needed to develop a whole VR platform for two different familiar environments. Less than 5 hours are required to complete the design process.

Keywords: 3D scanner , Brain stroke , Memory loss , Rehabilitation , Serious games , Virtual reality