3D scanning

Patients undergoing mastectomy for breast cancer have nowadays many options for breast reconstruction, that will help in re-establishing patient's self confidence in her own body image. Implant-based reconstruction remains the most common form of post-mastectomy reconstruction, but it could also present some complications, the most common being capsular contracture. Accordingly, a novel breast mound may be perfectly designed using the reverse engineering approach and additive manufacturing methods combined with autologous fat grafting. A 3D hierarchical structure with autologous adipose-derived stem cells may be used as a construct for tissue regeneration. The 3D morphologically controlled scaffold may be placed in the subcutaneous position at the level of the conservative mastectomy side. The scaffold will be colonized with autologous fat tissue in some sessions. The biodegradable customized structure will help to maintain the breast shape and the natural consistency may be obtained with the fat grafting, also considering adequate enhancement techniques (Stromal Vascular Fraction derived growth factors). The principles of regenerative medicine may be combined and integrated with those of reverse engineering (3D image capture, 3D modelling and rapid prototyping) to design custom-made and high functional hierarchical structures with tailored properties and 3D complex geometry. The current study will focus on the basic principles and strategies in designing 3D advanced and complex structures for breast repair and regeneration.

Keywords: Additive Manufacturing , Breast reconstruction , Fat Grafting , Reverse Engineering , Tissue Regeneration

Patients undergoing mastectomy for breast cancer have nowadays many options for breast reconstruction, that will help in re-establishing patient's self confidence in her own body image. Implant-based reconstruction remains the most common form of post-mastectomy reconstruction, but it could also present some complications, the most common being capsular contracture. Accordingly, a novel breast mound may be perfectly designed using the reverse engineering approach and additive manufacturing methods combined with autologous fat grafting. A 3D hierarchical structure with autologous adipose-derived stem cells may be used as a construct for tissue regeneration. The 3D morphologically controlled scaffold may be placed in the subcutaneous position at the level of the conservative mastectomy side. The scaffold will be colonized with autologous fat tissue in some sessions. The biodegradable customized structure will help to maintain the breast shape and the natural consistency may be obtained with the fat grafting, also considering adequate enhancement techniques (Stromal Vascular Fraction derived growth factors). The principles of regenerative medicine may be combined and integrated with those of reverse engineering (3D image capture, 3D modelling and rapid prototyping) to design custom-made and high functional hierarchical structures with tailored properties and 3D complex geometry. The current study will focus on the basic principles and strategies in designing 3D advanced and complex structures for breast repair and regeneration.

Keywords: Additive Manufacturing , Breast reconstruction , Fat Grafting , Reverse Engineering , Tissue Regeneration

Ultrasound is by far the most adopted method for safe screening and diagnosis in the prenatal phase, thanks to its non-harmful nature with respect to radiation-based imaging techniques. The main drawback of ultrasound imaging is its sensitivity to scattering noise, which makes automatic tissues segmentation a tricky task, limiting the possible range of applications. An algorithm for automatically extracting the facial surface is presented here. The method provides a comprehensive segmentation process and does not require any human intervention or training procedures, leading from the output of the scanner directly to the 3D mesh describing the face. The proposed segmentation technique is based on a two-step statistical process that relies on both volumetric histogram processing and 2D segmentation. The completely unattended nature of such a procedure makes it possible to rapidly populate a large database of 3D point clouds describing healthy and unhealthy faces, enhancing the diagnosis of rare syndromes through statistical analyses.

Keywords: 3D histogram processing , 3D ultrasound , DICOM , Image segmentation

Digital documentation and high-quality 3D representation are always more requested in many disciplines and areas due to the large amount of technologies and data available for fast, detailed and quick documentation. This work aims to investigate the area of medium and small sized artefacts and presents a fast and low cost acquisition system that guarantees the creation of 3D models with an high level of detail, making the digitalization of cultural heritage a simply and fast procedure. The 3D models of the artefacts are created with the photogrammetric technique Structure From Motion that makes it possible to obtain, in addition to three-dimensional models, high-definition images for a deepened study and understanding of the artefacts. For the survey of small objects (only few centimetres) it is used a macro lens and the focus stacking, a photographic technique that consists in capturing a stack of images at different focus planes for each camera pose so that is possible to obtain a final image with a higher depth of field. The acquisition with focus stacking technique has been finally validated with an acquisition with laser triangulation scanner Minolta that demonstrates the validity compatible with the allowable error in relation to the expected precision.

Keywords: Cultural heritage , Focus stacking , Photogrammetry , Small artefacts , Structure from motion

The integration of underwater 3D data captured by acoustic and optical systems is a promising technique in various applications such as mapping or vehicle navigation. It allows for compensating the drawbacks of the low resolution of acoustic sensors and the limitations of optical sensors in bad visibility conditions. Aligning these data is a challenging problem, as it is hard to make a point-to-point correspondence. This paper presents a multi-sensor registration for the automatic integration of 3D data acquired from a stereovision system and a 3D acoustic camera in close-range acquisition. An appropriate rig has been used in the laboratory tests to determine the relative position between the two sensor frames. The experimental results show that our alignment approach, based on the acquisition of a rig in several poses, can be adopted to estimate the rigid transformation between the two heterogeneous sensors. A first estimation of the unknown geometric transformation is obtained by a registration of the two 3D point clouds, but it ends up to be strongly affected by noise and data dispersion. A robust and optimal estimation is obtained by a statistical processing of the transformations computed for each pose. The effectiveness of the method has been demonstrated in this first experimentation of the proposed 3D opto-acoustic camera.

Keywords: Optical and acoustic integration , Opto-acoustic vision , ROV navigation , Underwater 3D imaging

The saddle is one of the most complex bicycle components providing both comfort and support while pedalling. Several studies have been carried out on bicycle saddles in recent years including medical ones to identify any correlated pathologies, and others to optimize design and sports performance. There are various types of commercially available saddles but they are all fixed geometry. The main identifiers of these designs are their length, nose inclination and the geometry of the support of the ischial tuberosities and pubic rami (wide, narrow, flat, furrowed etc.). So as the literature suggests, the fixed-geometry saddle on today's market has only partly resolved the anatomical pathologies related to extended saddle time. Consequently, the aim of this study is to develop, through interactive Re-design methodology, a variable geometry saddle (VGS) prototype for amateur cyclists capable of reducing the onset of saddle pathologies and improving pedalling comfort. The VGS was developed which can be adjusted to the physico-anatomical requirements of the rider as well as to various ride conditions (uphill, flat and downhill). The simple adjusters affect nose inclination and the width of the saddle back. In particular, the nose mechanism allows on-the-fly adjustment. The VGS developed could also allow the cyclist to identify the most congenial subjective geometry to help choose among commercial alternatives. An electroneurograph test on the pudendum nerve was also performed on five male amateur cyclists to see whether there were any effects with a variable saddle geometry compared to a fixed-geometry commercial saddle.

Keywords: Bicycle seat , Cycling , Interactive design , Rapid prototyping , Reverse engineering

In recent years virtual anthropology has been carrying out investigations as an alternative to the traditional anthropological approach. Among various applications is the study of the death masks of historically famous people, to authenticate them and make facial reconstructions. This study describes a multidisciplinary approach applied to the only three death masks of the musician Vincenzo Bellini made from different materials in different periods. By applying virtual anthropology along with Reverse Engineering, the morphological and metrical relationships of the masks were able to be studied, a study uniquely enabled in virtual environment. So, the finds were investigated without compromising their integrity also thanks to the use physical models obtained through Rapid Prototyping. Integrated with traditional artistic techniques, these methodologies provided evaluations of the historical, technical and morphological relationships between the death masks. Nevertheless, to refer these faces to Bellini, the results were compared with Bellini's autopsy data from Prof. Dalmas.

Keywords: Additive manufacturing , Death mask , Laser scanning , Superimposition techniques , Vincenzo Bellini , Virtual anthropology

Pier Paolo Valentini, PhD in Design of Mechanical Systems, is Associate Professor of Applied Mechanics. He is research fellow of the National Laboratories of Frascati (Rome) of the Italian Institute for the Nuclear Physics and member of the Steering Committee of the Italian Association of Machine Design. He teaches Virtual Prototyping and Simulation of Mechanical Systems and Bio-prosthesis. He has been advisor of more than 130 master and PhD dissertations. He has been principal investigator of more than 40 research projects funded by institutions and industrial partners. He has authored more than 130 papers in international journals and conference proceedings. Eugenio Pezzuti is Associate Professor of Machine Drawing. He is member of the advisory board of the Italian Ministry for Education, University and Research. He has been the principal investigator of three projects funded by national institutions. His fields of interests are the design of machine components, study on optimal tolerance allocations, reverse engineering methodologies and biomechanics. He has authored more than 80 papers in international journals and conference proceedings. The allocation of the right tolerances is one of the most important phases in the design process of mechanical devices and systems. In general, the choice has to take into account the manufacturing costs and limitations, looking at the specific functionality of the device and the assemblability of parts. In the case of flexible components, the designer has to include the evaluation of the compliance effects and the structural resistance. The paper discusses a numerical methodology for addressing the problem of the geometrical tolerance allocation for the compliant ortho-planar spring. The methodology is based on the definition of the functionality and resistance objective functions by means of finite element models. Numerical constrained optimisation is then applied to find the suitable combination of tolerance parameters acting on the main dimensions.

Keywords: Compliant mechanism , Flexible component , Ortho-planar spring , Tolerance allocation

A family of parametric 3D CAD models based on stochastic distribution of not-engineering real life object has been studied. The subject considered was the Tonda Gentile Trilobata (TGT) hazelnut variety, which is the most important variety in the Langhe region in Piedmont, Italy. The aim was to obtain a master model which measured, or stochastically-obtained, values of parameters given as input, to generate a number of samples which have the same statistical distributions of the real world ones. These generated models could then be used in virtual simulations of machinery and equipment used by industries to process the hazelnut, making possible studies of modifications to improve the production process performance. A single parametric CAD model was considered with respect to several scanned models from real hazelnuts, with the possibility of generating families of solutions suitable for the simulation aims. The work was carried out in steps of increasing complexity checking accuracy using different types of comparisons to validate the different models.

Keywords: Dried fruits , Feature-based modelling , Reverse engineering

This paper presents a method to evaluate the accuracy of a manufactured object with respect to its original CAD model. Different errors caused by the manufacturing process are assumed to come from global axis deformation and transverse sections rotation of the object with respect to its ideal CAD. Object and CAD shapes are given in form of point clouds, the former derived from a laser-scanning measurement, the latter from sampling the ideal surface by a dense and uniform point grid. Point clouds are sectioned in a finite number of thin blocks. This method has been applied to the analysis of a helical Darrieus blade prototype, parametrically designed and modelled with McNeel Rhinoceros and Grasshopper software, manufactured with a three-axes Computer Numerical Control machine. This procedure is able to check the conformity of the manufactured airfoil to the theoretical one and to establish the efficiency of the final prototype of the blade turbine.

Keywords: Point cloud , reverse engineering , shape accuracy

This paper presents an experimentation, which has been conducted in the underwater archaeological site of Capo Colonna, aimed to verify the joined use of optical and acoustic techniques for the generation of multi-resolution textured 3D models of underwater sites, obtained by merging the results of surveys carried out with these two types of systems.

In the field of additive manufacturing (AM) processes, there is a significant lack of scientific data on the performance of open-source 3D printers in relation to process parameter values. The purpose of this paper is to assess the impact of the main process parameters on the accuracy of a set of typical geometric features, as obtained with an open-source 3D printer, the RepRap Prusa-Mendel I2. For this purpose, a benchmarking part was set up, composed of elementary shapes, representing a series of different geometric features. By means of a DoE approach, it was possible to assess the effects of two process parameters - layer thickness (Lt) and flow rate (Fr) - on five geometric features: cube, sphere, cylinder, cone, and angled surface. A high resolution Laser Scanner was used to evaluate the variation between the acquired geometric feature and the corresponding 3D computer-aided design (CAD) nominal model. On the basis of experimental results, it was possible to analyze and discuss the main effects of the above-mentioned process parameters on each geometric feature. These results can help RepRap users in the correct selection of process parameters with the aim of improving the quality of prototypes.

Keywords: geometric features , laser scanner , open-source 3D Printers , process parameters

With a view to enabling additive manufacturing (AM) processes, today, open-source, low-cost 3D printers are systems with great potential. However there is a significant lack of scientific data on the performance of open-source 3D systems and on the selection of adequate process parameters that can help to improve the quality of the parts. The purpose of this paper is to assess the effects of the main process parameters on the dimensional accuracy of a specific open-source 3D printer, the RepRap Prusa-Mendel I2. This study consisted of a benchmarking part, involving elementary shapes representing a series of different features. By means of a full factorial DoE (Design of Experiments), with three factors (layer thickness, deposition speed, and flow rate), three levels, and three replications, 81 parts were obtained. Subsequently, a laser scanner (D700 Laser Scanner-3Shape, Denmark) was used as high resolution reverse engineering system in order to evaluate the variation between real parts and nominal geometry. The impact of the main process parameters was evaluated and optimal combinations were analyzed. On the basis of the results obtained in the experiments, practical suggestions for the settings of common process parameters were formulated. Test results serve to improve the quality of AM parts through the most appropriate selection of the main process parameters.

A technique to obtain the kinematic calibration of multilink systems is presented. The technique that is based on a digital photogrammetry vision system and the D-H based kinematic equations, can be considered as a reverse engineering aspect. The most important aspects of this technique consist in that no information on the kinematics chain is needed, it is fast, low cost, non invasive and also friendly for the operator. Tests of the technique on a revolute robot are also reported, showing a good reliability of the technique itself.

Keywords: Digital photogrammetry , Kinematic calibration , Reverse engineering , Robot mechanics

Aim of this paper is to describe a research activity on the virtual prototyping, by means of the Reverse Engineering techniques, of an automotive semi-active,differential based on the use of a Magneto-Rheological Fluid. The MRF allows to control the locking torque and consequently to improve the vehicle handling. Starting from the 3D digitizing and the virtual reconstruction of a gearbox of a common front wheel drive vehicle, the boundary volume of the new device (MRF LSD) was defined and a preliminary CAD model was realized. Then, optimizing its dimensions and choosing the adequate materials, the final virtual prototype was obtained. The successive GD&T phase allowed to get the best assembly procedure and quality of the final model of the new device. In order to evaluate the goodness of the virtual simulations realized and of the results proposed, a physical prototype was manufactured. Finally, several experimental tests were carried out to validate the design process.

Keywords: 3D CAD parametric , Automotive differential , Magneto-rheological fluid , Reverse engineering , Virtual prototyping techniques

The diffusion of depth sensors to sense people and objects constitutes an outstanding opportunity in those fields in which the benefits of optical marker-less solutions for scanning or tracking are requested. This paper shows how two different applications based on MS Kinect device can be accomplished in the domain of lower limb prosthesis design and test. The first one refers to the use of a depth camera as a three-dimensional scanner to acquire the geometry of residual limbs or of custom-fit components. The second application is related to the motion capture of patients' gait with the prosthesis. In both cases, the technology resulted to be better than many traditional ones mainly for its limited invasivity, interesting performance, portability and low cost.

Keywords: 3D scanner , Digital human modelling , Lower limb prosthesis , Motion capture , RGB-D cameras

The diffusion of depth sensors to sense people and objects constitutes an outstanding opportunity in those fields in which the benefits of optical marker-less solutions for scanning or tracking are requested. This paper shows how two different applications based on MS Kinect device can be accomplished in the domain of lower limb prosthesis design and test. The first one refers to the use of a depth camera as a three-dimensional scanner to acquire the geometry of residual limbs or of custom-fit components. The second application is related to the motion capture of patients' gait with the prosthesis. In both cases, the technology resulted to be better than many traditional ones mainly for its limited invasivity, interesting performance, portability and low cost.

Keywords: 3D scanner , Digital human modelling , Lower limb prosthesis , Motion capture , RGB-D cameras

In the field of orthodontic planning, the creation of a complete digital dental model to simulate and predict treatments is of utmost importance. Nowadays, orthodontists use panoramic radiographs (PAN) and dental crown representations obtained by optical scanning. However, these data do not contain any 3D information regarding tooth root geometries. A reliable orthodontic treatment should instead take into account entire geometrical models of dental shapes in order to better predict tooth movements.This paper presents a methodology to create complete 3D patient dental anatomies by combining digital mouth models and panoramic radiographs. The modeling process is based on using crown surfaces, reconstructed by optical scanning, and root geometries, obtained by adapting anatomical CAD templates over patient specific information extracted from radiographic data. The radiographic process is virtually replicated on crown digital geometries through the Discrete Radon Transform (DRT). The resulting virtual PAN image is used to integrate the actual radiographic data and the digital mouth model. This procedure provides the root references on the 3D digital crown models, which guide a shape adjustment of the dental CAD templates. The entire geometrical models are finally created by merging dental crowns, captured by optical scanning, and root geometries, obtained from the CAD templates.

The geometrical reconstruction of centrifugal pump impellers is a strategic activity for many manufacturing industries. In particular, the digitalization of internal hydraulic shapes represents the most critical task due to the difficulties in accessing the internal parts of impeller disks. In this paper, an automatic approach to digitize the internal shape of impellers is presented. The methodology is based on the integration of optical and probing methods in order to combine the advantages of both technologies. The developed approach uses an optically tracked hand-held probe designed to digitize, point-by-point, the whole surface of blades. The tracking system is based on a passive device, composed of two stereo cameras, which is used to accurately locate a specific plate, rigidly connected to a probe. The proposed methodology has been validated by experimental tests on primitive surfaces as plane, cylinders and spheres. Nonetheless, the robustness and flexibility of the developed technique has allowed the whole reconstruction of industrial impellers through the acquisition of hundreds of points in few minutes.

Within the orthodontic field, malocclusion problems are usually treated by using different types of appliances. In particular, Eruption Guidance Appliances (EGAs) are recommended for early orthodontic treatment or prevention of malocclusion problems. The traditional approach with EGAs is based on the use of standard prefabricated appliances. Experts in the orthodontic field believe that the customization of the EGAs would strongly enhance the results of malocclusion treatments. This paper presents an innovative methodology for the design and manufacturing of fully customized EGAs. The methodology is based on an extensive integration between traditional orthodontic procedures with advanced computer aided design processes. The methodology moves from the digitalization of the plaster models obtained by optical scanning techniques. The patient morphology is then exploited, under dental practitioner supervision, for the design of the appliance geometry through CAD modeling tools. Medical guided assessment is required throughout the most of the data elaboration processes, in order to design the EGAs accordingly to the patient's clinical conditions. Low-pressure injection molds for the physical manufacturing of the appliances are then 3D printed by using rapid prototyping techniques. The proposed methodology allows the production of patient customized appliances guaranteeing low cost manufacturing and high quality standards, similar to those typically obtained by in series productions. Moreover, the presented approach offers a high integration level with numerical and finite element methods, which can be used for evaluating the stress applied on the EGA, thus allowing the reinforcement of the appliance prior its manufacturing.