Abstract: Submerged lifting surfaces technology, born in the early 1900s, allows boats to lift the hull above the water and, in some cases, halves the resistance compared to dislocated and planning boats. This paper illustrates the state-of-the-art on hydrofoil technology, highlighting the fundamental aspects of the study of submerged wings and focusing on the problems that this technology presents, evaluating the solutions currently used to optimize its work. Key aspects of hydrofoil design are addressed, such as the choice of geometric configurations and two-dimensional profiles suitable for each type of mission. This results in addressing issues associated with cavitation and ventilation and emphasizing structural solutions that reduce these phenomena, thus improving hydrofoil efficiency. The study analyses and discusses the problems of wing systems used in existing applications, with the aim of developing a sustainable transport technology compatible with ecological propulsions such as hydrogen and electric.

Keywords: green | hydrodynamics | hydrofoil | sustainable

Abstract: The paper presents a preliminary design activity and virtual prototyping of an innovative boat equipped with hydrofoils and hybrid propulsion, with the aim of extending the foil technology from the field of competition boats to recreational day-cruiser yachts and creating a craft with minimal environmental impact. Hydrofoils allow boats to rise from the water, greatly reducing resistance and increasing performance. The current work dealt with the preliminary design of a daysailer with foil technology and hybrid propulsion that allow to combine green and comfortable navigation both under sail and motor and that, when required, can sail in a more performing way by exploiting the foil technology and the thrust of the wind. After having deepened the theory and physics of sailing on foils, a MATLAB code was created to integrate the stability equations that characterize hydrofoil sailboats: connecting the acting forces and allowing to define the dimensions of the geometries, the code was fundamental in speeding up the iterative preliminary design process. The next step was to model the geometry of the hull and the appendages in the CAD environment and, subsequently, the wing movement mechanism so that it could both manage the incidence of the wings and retract the foils when the boat is moored. The hull, profiles, and wings were subsequently placed in a CFD and VPP virtual environment for testing their resistance. Future developments will include a detailed design and the physical prototyping of a first boat for water testing.

Keywords: Green | Hybrid | Hydrofoil | Virtual prototyping

Abstract: This paper presents the results of a survey carried out with students enrolled in the first two years of the BS in Engineering at three Italian university locations. The study is part of a wider range of methods, tools and aids for the improvement of teaching and learning of technical drawing at university level developed by the University of Brescia, Udine, and Cassino and Southern Lazio. In particular, this work analyses the results of questionnaires related to the basic technical drawing outcomes, taking inspiration from previous research work in this field. What emerges is a positive picture that shows students’ interest in 3D CAD modeling topics such as part or assembly construction, but also their interest in more traditional subjects like sketching and dimensioning.

Keywords: CAD | Engineering education | Students’ surveys | Technical drawing

Abstract: It has been widely reported that breast reconstruction improves the quality of life of women who undergo mastectomy for breast cancer. This approach provides many psychological advantages. Today, different techniques are available for the breast oncoplastic surgeon that involve the use of breast implants and autologous tissues, also offering interesting results in terms of aesthetic and patient-reported outcomes. On the other hand, advanced technologies and design strategies (i.e. design for additive manufacturing, reverse engineering) may allow the development of customised porous structures with tailored morphological, mechanical, biological, and mass transport properties. For this reason, the current study deals with the challenges, principles, and methods of developing 3D additive manufactured structures in breast reconstructive surgery. Specifically, the aim was to design 3D additive manufactured poly(ε-caprolactone) scaffolds with different architectures (i.e. lay-down patterns). Preliminary mechanical and biological analyses have shown the effect of the lay-down pattern on the performances of the manufactured structures.

Keywords: Additive manufacturing | Breast reconstructive surgery | Fat grafting | Functional properties | Mechanical | Pore geometry and lay-down pattern | Reverse engineering | Scaffold design

Abstract: In this work is analyzed the possibility to use optical techniques for the characterization of airless radial tire. Electronic Speckle Pattern Interferometry (ESPI), laser scanner based on principle of triangulation and Digital Image Correlation (DIC) have been used to acquire and study this kind of tire. A MICHELIN® X® TWEEL® UTV has been considered as case study. The acquisitions have been used for the measurement of the shape for testing junction areas and to evaluate the structure behavior under a vertical load.

Keywords: Composite laminates | Laser scanner | NDI | Tire

Abstract: Since students attending basic engineering courses are numerous and show different background regarding high school, experience, skills and attitudes, it has become important for educators to assess the level of their prior knowledge. In Italy, in order to access university engineering courses (BS degree level), students usually must take an entrance test; it assesses their knowledge about basic subjects such as mathematics, physics and chemistry, as well as their logical and linguistic skills. However, this test does not refer to technical subjects, e.g., the technical drawing. The two university research units of Udine and Brescia collaborate in developing the Technical Drawing Test-Level 0 (TDT-L0), a test-based method to assess students’ prior knowledge about basic engineering graphics topics like axonometric and orthographic projections, sectional views, basic dimensioning standards, etc. This paper describes the definition of the test contents - the selection of the questions to ask to the students - as well as the way to analyze the collected information and exploit the results to improve the learning and teaching experience of both students and educators. An adoption of the TDT-L0 at the University of Udine is reported as first validation.

Keywords: Engineering education | Prior knowledge assessment | Technical drawing | Test

Abstract: High fidelity calculation tools are well established in the nautical design sector where advanced numerical simulations are adopted for the prediction of the interaction of boat parts with surrounding fluids. The capability to couple such tools with efficient shape parametrization procedures offers the possibility to further improve the performance speeding up the design process. Radial Basis Functions (RBF) Mesh Morphing (MM) allows to quickly modify the shape within numerical domains without the need of updating the underlying CAD representation. The validity of this approach, widely adopted in aeronautical and automotive fields, is demonstrated in this paper by applying the method to the analysis of the flying shape of a symmetric spinnaker also investigating the importance of panel arrangement on sail characteristics. The performance, in terms of drive and side forces, is evaluated for different morphed geometries by RANS (Reynolds Averaged Navier Stokes) analyses. The RBF setup proved to be efficient and robust in generating a good quality of the morphed domain within the full range of amplification from the undeformed to the flying shape geometry.

Keywords: Drive and side force | Geometric parametrization | Mesh morphing | Radial basis functions | RANS analysis | Symmetric spinnaker

Abstract: The book was inadvertently published with an error in Chapter 50. The author’s name has been changed from ‘Barbara Moty’ to ‘Barbara Motyl’.

Abstract: High-flexibility components in composite material are of great interest in many fields, from aeronautic and automotive industries to sport and design goods. Their deformation during cure process, known as spring-in and warpage, is acceptable if it is within the indicated tolerance. The research aim of the present work is to present a way to inspect a high flexible part in composite material by means of a coordinate measuring machine with a touch probe. This means to define the fixturing equipment and the measurement strategy. The developed method was applied to an L-shaped part with a very small thickness and the obtained measurements were compared with those due to a laser system. The results show a good agreement between the two measurement techniques. Moreover, the further numerical simulations validate the developed contact measurement method.

Keywords: Composite material | Coordinate measuring machine | Flexible component | Laser

Abstract: Many women with early breast cancer undergo mastectomy as a consequence of an unfavorable tumor/breast ratio or because they prefer this option to breast conservation. As reported, breast reconstruction offers significant psychological advantages. Several techniques are currently available for the breast oncoplastic surgeon and offer interesting results in terms of aesthetic and patient-reported outcomes, using both breast implants and autologous tissues. On the other hand, advanced methodologies and technologies, such as reverse engineering and additive manufacturing, allow the development of customized porous scaffolds with tailored architectures, biological, mechanical and mass transport properties. Accordingly, the current research dealt with challenges, design methods and principles to develop 3D additively manufactured structures in breast reconstructive surgery.

Keywords: additive manufacturing | breast reconstructive surgery | design | fat grafting | reverse engineering | scaffold design

Abstract: Surgical interventions for jaw reconstruction require the design and the production of surgical guides that allow the surgeon to operate quickly and accurately. In some cases, the reconstruction is performed by inserting a prothesis, thus operating exclusively on the jaw, while in other cases the reconstruction is performed by withdrawing and inserting part of the fibula in place of the original jaw bone. This project aims to develop a procedure that allows 3D modeling of the surgical guides necessary for surgical intervention. The idea is to find a surgical guide archetype, a starting shape for the surgeon so that the cutting planes can be oriented without the surgical guide having to be redesigned from scratch for every single patient. The first step of the procedure is the segmentation, performed applying the thresholding operation on the images provided by magnetic resonance MR in order to identify the region of interest (ROI). The second step is the reconstruction of the 3D model, so that a mesh is obtained from 2D images. Subsequently the mesh is post-processed and the cutting plans along which the surgeon will intervene are defined.

Keywords: 3D modeling | 3D reconstruction | Maxillofacial surgery | Surgical guides

Abstract: This paper deals with parenthood perception (maternal and paternal) after the visualization and interaction (touch) with a 3D printed facial fetal model. The model is created using Additive Manufacturing techniques, starting from the image elaboration of routine ultrasound data. In this study, the method used for the elaboration and construction of 3D printable models of fetal faces starting from routine ultrasound images is briefly described. In addition, we present the results of a new survey conducted with future parents at the Altamedica clinic (Rome, Italy) to verify whether there are any benefits derived from the use of 3D printing models with future parents, both regarding the improvement of the parenthood experience, and the improvement of the understanding and collaboration with the physicians in case of fetal malformations, using 3D models coupled with the data of routine ultrasound examinations.

Keywords: 3D ultrasound | Additive manufacturing | Fetal face | Image processing | Parenthood perception | Survey

Abstract: Computational Fluid Dynamics (CFD), as early used in the design stage, helps engineers to come up with the optimum design of a sail in a reasonable timeframe. However, traditional CFD tools are approximate and need to be validated when it comes to predicting the dynamic behaviour of non-developable shape with high camber and massively detached flow around thin and flexible membranes. Some of these approximations are related to the implementation of the constitutive material characteristics and assumption of their isotropic properties, while the sail aerodynamic performance is strongly influenced by the arrangement of sail panels as well as the orientation of the fibres in the composite structure. The present paper offers a methodology that enhances the understanding of the influence of panel arrangement and fibre orientation on sail performance. Fluid-structure-interaction (FSI) in a symmetric spinnaker was studied through an integrated CFD-CSM (Computational Structural Mechanics) analysis. A suitable triangular membrane element formulation of sail was adopted and the constitutive characteristics (elasticity and damping) of the Nylon superkote 75 were implemented in CSM model after being experimentally measured. The aerodynamic performance of sail in terms of drive force and side force was evaluated using both Reynolds Averaged Navier Stokes Simulations (RANS) and Shear Stress Transport (SST) turbulence model with a finite volume approach. A comparison between different panel arrangements was carried out under altered downwind flow conditions of wind speed and wind angle. Digital photogrammetry was employed to create the 3D reconstruction of the sail's flying shape and validate the results obtained by aeroelastic analysis.

Keywords: CFD-CSM analysis | Flying shape photogrammetry acquisition | Sail panel arrangement | SST model | Triangular membrane elements

Abstract: In this work is exploited the possibility to use two optical techniques and combining their measurements for the 3D characterization of different tyres with particular attention to the tyre's section. Electronic Speckle Pattern Interferometry (ESPI) and Laser Scanner (LS) based on principle of triangulation have been employed for investigating and studying the tyre's section and 3D shape respectively. As case studies two different racing tyres, Michelin S9H and Pirelli Diablo respectively, have been considered. The investigation has been focused at the aim to evaluate and measure the section's components in order to add to the 3D model obtained by Laser Scanning accurate information about the different layers along through the tyres sections. It is important to note that the assessment about the different layers along the section is a very difficult task to obtain by visual inspection or classical microscopy and even with the LS. Here we demonstrate that the different layers can be easily highlighted and identified by mean of the ESPI.

Keywords: Holography | Laser scanner | Non-destructive testing | Speckle | Tyre characterization | Tyre layer thickness measurement

Abstract: The use of intraoral scanners and Additive Manufacturing (AM) techniques in dentistry is increasing, and such technologies are integrated in daily workflows for the production of various types of dental restorations. Thus, it is clinically sensible to assess the accuracy of these systems. This in vivo study presents a comparison, in term of accuracy, among three commercially available AM systems, used to rapid prototype models obtained from intraoral scans data. Eight patients with a complete dentition were selected. Complete-arch scans of both upper and lower jaws were obtained using the 3Shape Trios 3 color intraoral scanner. The corresponding CAD models were created by means of the 3Shape Dental System software, and three AM systems, Photocentric LC10 (AM1), Zortrax M 200 (AM2) and Prusa I3 (AM3) were used to manufacture them. The manufactured fourty-eight models were scanned with the 3Shape Trios 3 color scanner, by the same operator. Scans of the manufactured models were aligned and compared to the reference intraoral scan by means of a Reverse Engineering software (Geomagic Studio). The comparison between the scans of the manufactured models and the reference intraoral scans, for the eight patients, shows a standard deviation (SD) in the range 0.11 – 0.27 mm for AM1, in the range 0.04 – 0.26 mm for AM2 and in the range 0.07 – 0.26 mm for AM3. The results of this research show that Prusa I3 and Zortrax M 200 are statistically more accurate than Photocentric LC10. Nevertheless, if we consider the amount of difference in accuracy, this may be not relevant from a clinical point of view. Thus, the three AM systems can be used in some dental applications which are compatible with the reported accuracy.

Keywords: Additive manufacturing | Dental models | Dentistry | Intraoral scans | Orthodontic appliances

Abstract: Ultrasound scans, Computed Axial Tomography, Magnetic Resonance Imaging are only few examples of medical imaging tools boosting physicians in diagnosing a wide range of pathologies. Anyway, no standard methodology has been defined yet to extensively exploit them and current diagnoses procedures are still carried out mainly relying on physician's experience. Although the human contribution is always fundamental, it is self-evident that an automatic procedure for image analysis would allow a more rapid and effective identification of dysmorphisms. Moving toward this purpose, in this work we address the problem of feature extraction devoted to the detection of specific diseases involving facial dysmorphisms. In particular, a bounded Depth Minimum Steiner Trees (D-MST) clustering algorithm is presented for discriminating groups of individuals relying on the manifestation/absence of the labio-schisis pathology, commonly called cleft lip. The analysis of three-dimensional facial surfaces via Differential Geometry is adopted to extract landmarks. The extracted geometrical information is furthermore elaborated to feed the unsupervised clustering algorithm and produce the classification. The clustering returns the probability of being affected by the pathology, allowing physicians to focus their attention on risky individuals for further analysis.

Keywords: Artificial intelligence | Clustering | D-MST | Decision support | Diagnosis | Facial dysmorphism | Feature extraction | Labio-schisis | Landmarking

Abstract: Understanding the mechanisms of traumatic ocular injury is helpful to make accurate diagnoses before the symptoms emerge and to develop specific eye protection. The comprehension of the dynamics of primary blast injury mechanisms is a challenging issue. The question is whether the pressure wave propagation and reflection alone could cause ocular damage. To date, there are dissenting opinions and no conclusive evidence thereupon. A previous numerical investigation of blast trauma highlighted the dynamic effect of pressure propagation and its amplification by the geometry of the bony orbit, inducing a resonance cavity effect and a standing wave hazardous for eye tissues. The objective of the current work is to find experimental evidence of the numerically identified phenomenon. Therefore, tests aimed at evaluating the response of porcine eyes to blast overpressure generated by firecrackers explosion were performed. The orbital cavity effect was considered mounting the enucleated eyes inside a dummy orbit. The experimental measurements obtained during the explosion tests presented in this paper corroborate the numerical evidence of a high-frequency pressure amplification, enhancing the loading on the ocular tissues, attributable to the orbital bony walls surrounding the eye.

Keywords: Amplification | Experimental study | Orbital cavity | Pressure standing wave | Primary blast injury

Abstract: This work proposes a methodology to automatically diagnose and formalize prenatal cleft lip with representative key points and identify the type of defect (unilateral, bilateral, right, or left) in three-dimensional ultrasonography (3D US). Differential Geometry has been used as a framework for describing facial shapes and curvatures. Then, descriptors coming from this field are employed for identifying the typical key points of the defect and its dimensions. The descriptive accurateness of these descriptors has allowed us to automatically extract reference points, quantitative distances, labial profiles, and to provide information about facial asymmetry. Seventeen foetal faces, nine of healthy foetuses and eight with different types of cleft lips, have been obtained through a Voluson system and used for testing the algorithm. In case no defect is present, the algorithm detects thirteen standard facial soft-tissue landmarks. This would help ultrasonographists and future mothers in identifying the most salient points of the forthcoming baby. This algorithm has been designed to support practitioners in identifying and classifying cleft lips. The gained results have shown that differential geometry may be a valuable tool for describing faces and for diagnosis.

Keywords: 3D ultrasound | Cleft lip | Dysmorphisms | Landmarking | Syndrome diagnosis

Abstract: This paper deals with additive manufacturing techniques for the creation of 3D fetal face models starting from routine 3D ultrasound data. In particular, two distinct themes are addressed. First, a method for processing and building 3D models based on the use of medical image processing techniques is proposed. Second, the preliminary results of a questionnaire distributed to future parents consider the use of these reconstructions both from an emotional and an affective point of view. In particular, the study focuses on the enhancement of the perception of maternity or paternity and the improvement in the relationship between parents and physicians in case of fetal malformations, in particular facial or cleft lip diseases.

Abstract: The use of polymer composites has been increasing over the years and nowadays the requirements for designing high performance and lightweight fabrics and laminates for sail manufacturing have become more stringent than ever. The present paper offers an effective methodology that enhances the understanding of the influence of fibres orientation and arrangement of panels on sail performance. Constitutive characteristics of the ten commonly used sail cloths are experimentally measured and their influence on sail dynamic performance is compared using an aerodynamic approach. As expected also in industry 4.0 the method allows to control the production process and final product optimization.

Keywords: Aerodynamic coefficient | Apparent wind angle (AWA) | Apparent Wind Speed (AWS) | CFD analysis | Digital photogrammetry | RE | Turbulence model

Abstract: Industry 4.0 represents one of the most challenging themes for engineering design and also for engineering education. At this moment there are few studies in the field of engineering teaching that aim to investigate how the educational needs of students and of the industrial workforce are changing. On this basis, this research would like to investigate which are the necessary skills and expertise young engineers require to be ready for the Industry 4.0 framework. In particular, a questionnaire was developed to analyze this situation. It has been administered to students enrolled in the first and second year of the engineering undergraduate degrees held in three Italian universities: Brescia, Udine and Cassino. During two different academics years, a total of 463 students participated to the survey. The questions were aimed to investigate some key issues of Industry 4.0, and the students’ digital belief and behaviors at their entrance in the university education system. The collected answers provided a picture of the actual situation in these three universities with some relevant considerations about engineering education. So, the fundamental question that authors want to answer is “Are the Italian engineering students effectively ready for Industry 4.0 or do we still work on it?”

Keywords: digital skills | Engineering Education | Industry 4.0 | questionnaire | student skills

Abstract: 3D face was recently investigated for various applications, including biometrics and diagnosis. Describing facial surface, i.e. how it bends and which kinds of patches is composed by, is the aim of studies in Face Analysis, whose ultimate goal is to identify which features could be extracted from three-dimensional faces depending on the application. In this study, we propose 54 novel geometrical descriptors for Face Analysis. They are generated by composing primary geometrical descriptors such as mean, Gaussian, principal curvatures, shape index, curvedness, and the coefficients of the fundamental forms. The new descriptors were mapped on 217 facial depth maps and analysed in terms of descriptiveness of facial shape and exploitability for localizing landmark points. Automatic landmark extraction stands as the final aim of this analysis. Results showed that the newly generated descriptors are suitable to 3D face description and to support landmark localization procedures.

Keywords: 3D Face | Face Analysis | Face Recognition | Geometry | Landmarks

Abstract: This work present some best practice cases in teaching technical drawing done by three Italian Universit ies: Brescia, Udine, and Cassino and Southern Lazio. The intention to innovate and improve the basic technical drawing courses offered by these three Universities started in 2014. The objective of this collaboration was the development of some tools to help the students in understanding the fundamental concepts of technical drawing. The first tool developed, in order of time, was the Technical Drawing Evaluation Grid – TDEG. Starting fro m this tool, other learning aids were developed for the undergraduate engineering st u-dents. Some of them are: an online test for students’ self-assessment of technical drawing knowledge; a questionnaire to collect students’ opinions on different technical drawing and engineering design topics; a method for the improvement of students’ motivation to study; and a self-learning tool for teaching manufacturing dimensioning. The preliminary results of these different practices are presented and discussed in the following, posing the basis of the definition of some best practice methods that can be used for the improvement of the teaching and learning of technical drawing basic concepts for engineering students.

Keywords: Best practices | Collaboration | Teaching & learning tools | Technical drawing

Abstract: Sail manufacture has undergone significant development due to sailing races like the America’s Cup and the Volvo around the World Race. These competitions require advanced technologies to help increase sail performance. Hull design is fundamentally important but the sails (the only propulsion instrument) play a key role in dynamic of sailboats. Under aerodynamic loads, sail cloth deforms, the aerodynamic interaction is modified and the pressure on the sails is variously distributed resulting in performance inconsistencies. The interaction between fluid and structure necessitates a solution which combines aerodynamic and structural numerical simulations. Furthermore, in numerical simulations the aeroelastic sail characteristics must be known accurately. In this paper, the dynamic performance of a Spinnaker was studied. Digital photogrammetry was used to acquire the images, make the 3D reconstruction of the sail and validate the models in Computational Fluid Dynamics (CFD) analysis. Orthotropic constitutive characteristics of ten different sail cloths were measured by experimental test. The methodology allowed to compare dynamic performance in terms of forces, pressure and vibration for the different sail cloths and different fiber orientations.

Keywords: CFD analysis | Detached eddy simulations | Pressure distributions | Sail aerodynamics | Turbulence models

Abstract: A 3D automatic facial expression recognition procedure is presented in this work. The method is based on point-by-point mapping of seventeen Differential Geometry descriptors onto the probe facial depth map, which is then partitioned into seventy-nine regions. Then, features such as mean, median, mode, volumes, histograms are computed for each region and for each descriptor, to reach a varied large set of parameters representing the query face. Each set of parameters, given by a geometrical descriptor, a region, and a feature, form a trio, whose featuring numerical values are compared with appropriate thresholds, set via experimentation in a previous phase by processing a limited portion of the public facial Bosphorus database. This allows the identification of the emotion-based expression of the query 3D face among the six basic ones (anger, disgust, fear, joy, sadness, surprise). The algorithm was tested on the Bosphorus database and is suitable for applications in security, marketing, medical. The three-dimensional context has been preferred due to its invariance to different lightening/make-up/camouflage conditions.

Keywords: 3D face | Differential geometry | Emotions | Face expression recognition (FER) | Facial expression recognition | Shape index

Abstract: The aim of this work is to automatically diagnose and formalize prenatal cleft lip with representative key points and identify the type of defect (unilateral, bilateral, right, or left) in three-dimensional ultrasonography (3D US). Geometry has been used as a framework for describing facial shapes and curvatures. Then, descriptors coming from this field are employed for identifying the typical key points of the defect and its dimensions. The descriptive accuracy of these descriptors has allowed us to automatically extract reference points, quantitative distances, labial profiles, and to provide information about facial asymmetry. Eighteen foetal faces, ten of healthy foetuses and eight with different types of cleft lips, have been obtained through a Voluson system and used for testing the algorithm. Cleft lip has been diagnosed and correctly characterized in all cases. Transverse and cranio-caudal length of the cleft have been computed and upper lip profile has been automatically extract to have a visual quantification of the overall labial defect. The asymmetry information obtained is consistent with the defect. This algorithm has been designed to support practitioners in identifying and classifying cleft lips. The gained results have shown that geometry might be a proper tool for describing faces and for diagnosis.

Keywords: 3D ultrasound | Cleft lip | Dysmorphisms | Landmarking | Syndrome diagnosis

Abstract: Documentation of maritime heritage is essential for its protection, and for reference in restoration and renovation processes. These functions become problematic in the case of historical ships and boats that lack lines drawings. The purpose of this paper is to describe a procedure for creation of lines drawings based on the shape analysis of surviving historical boats or their small-scale models with the help of reverse engineering (RE) techniques. The paper describes how digital photogrammetry and the iterative method were used to analyze the shape of three historical boats: Tomahawk, Refola and Nada. The application of the proposed procedure produced the lines drawings of the boats as its result. The accuracy of the 3D CAD model obtained with the photogrammetric technique was verified by comparing it against a more accurate 3D model produced with the help of a RE laser scanner. The examination of the resulting lines drawings proves that the digital photogrammetry process and the proposed iterative method are adequate tools for developing lines plans of boat models. The research offers the methodological basis for the creation of an archive of lines drawings of historical boats. Such an archive would provide reference for philologically correct restorations, and permit definition and classification of distinctive elements of various types of historical boats, particularly those produced in the Campania Region. © 2014 Springer Science+Business Media New York.

Keywords: 3D CAD models | Digital photogrammetry | Laser scanning | Maritime heritage documentation | Philological reconstruction | Reverse engineering

Abstract: In the last decade, three-dimensional landmarking has gained attention for different applications, such as face recognition for both identification of suspects and authentication, facial expression recognition, corrective and aesthetic surgery, syndrome study and diagnosis. This work focuses on the last one by proposing a geometrically-based landmark extraction algorithm aimed at diagnosing syndromes on babies before their birth. Pivotal role in this activity is the support provided by physicians and 3D ultrasound tools for working on real faces. In particular, the landmarking algorithm here proposed only relies on descriptors coming from Differential Geometry (Gaussian, mean, and principal curvatures, derivatives, coefficients of first and second fundamental forms, Shape and Curvedness indexes) and is tested on nine facial point clouds referred to nine babies taken by a three-dimensional ultrasound tool at different weeks' gestation. The results obtained, validated with the support of four practitioners, show that the localization is quite accurate. All errors lie in the range between 0 and 3.5 mm and the mean distance for each shell is in the range between 0.6 and 1.6 mm. The landmarks showing the highest errors are the ones belonging to the mouth region. Instead, the most precise landmark is the pronasal, on the nose tip, with a mean distance of 0.55 mm. Relying on current literature, this study is something missing in the state-of-the-art of the field, as present facial studies on 3D ultrasound do not work on automatic landmarking yet.

Keywords: 3D echography | 3D face | 3D ultrasound | Dysmorphisms | Landmarking | Syndrome diagnosis