Abstract: Lung cancer is the second neoplasia for incidence and the leading cause of death from neoplasia in the world. A consolidated practice for lung cancer early diagnosis and staging is EBUS TBNA (EndoBronchial UltraSound-guided TransBronchial Needle Aspiration). Despite being a low-risk procedure, its success highly depends on the medical staff’s skills, who therefore require appropriate training. With the future aim of developing a novel realistic EBUS TBNA simulator that also allows tissue sampling, in this paper, the authors propose a simplified representation of the mediastinum to define a suitable layout. As far as the authors know, the physical commercially-available simulators have poor echogenic properties, do not allow tissue sampling, and can be quite expensive. The project was carried out within Custom3D, a joint laboratory between Careggi Hospital of Florence and the Department of Industrial Engineering of the University of Florence, under the request of the interventional pneumology ward. The model was validated by an expert medical doctor who assessed its anatomical accuracy and the suitability of its mechanical and acoustic properties. Moreover, the possibility of performing lymph node needle aspiration is an added value that promises to bring the EBUS TBNA simulation to a new level of realism.

Keywords: EBUS TBNA | echogenic | mannequin | simulation

Abstract: Siren noise constitutes a nuisance and could be harmful for ambulance personnel and patients. Several studies proposed simulated Active Noise Control (ANC) solutions to attenuate siren noise inside an ambulance. In this paper an implementation of a feedforward ANC system based on the classic FxLMS algorithm is presented, running it on a real-time hardware platform to test the efficacy of such solution in a laboratory environment. Algorithms are developed in MATLAB Simulink environment, and run on Speedgoat target hardware. The results of these experiments are presented, and while discussing our findings, the experienced limitations are described, and further work is suggested.

Keywords: Active Noise Control | Ambulance Siren Noise | Feedforward ANC | FxLMS Algorithm | Real-time Hardware Test

Abstract: Tracheomalacia (TM) is a tracheal weakening that causes the cartilage structure to collapse during breathing. The term tracheobronchomalacia (TBM) is used when the bronchi are also implicated in the disease. This illness can be treated in a variety of methods, including the insertion of stents in the cartilage-restricted region. Stents are commercially available in numerous sizes (diameter and length), different shapes and materials. The shape of the stent is chosen based on where the disease is located, while the size is derived from measurements on CT images or by endoscopic investigations. This task is extremely critical for the patient's health since improper stent can have serious and even deadly repercussions for the patient. Therefore, it is necessary to choose a stent that fits the patient's anatomy as closely as possible. To this end, it is possible to employ a three-dimensional model of the investigated anatomy and choose the most suitable type of stent following measurements made on the model itself. In this work, a method to assist physicians in the choice of the stent to be used in TM or TBM patients, is proposed. By analyzing the tracheobronchial tree and measuring successive cross-sections along the centerline of the lumen, the automated procedure allows to localize the diseased area and to identify the optimal shape and size of the stent to be implanted. Four case studies of paediatric patients were performed and the results were validated by a team of physicians specialized in the treatment of upper and lower airways.

Keywords: 3D modelling | Airway obstruction | Reverse engineering | Stent

Abstract: The optimization of a galvanic process is a crucial task for many manufacturers in the field of electro-deposition industry. This is true for companies operating in the high fashion field, in which expensive materials are used and reducing material waste is crucial. In this paper, the estimation of the wet surface of small metal parts is treated. In fact, considering a single piece, the amount of material required to guarantee a desired plate thickness is directly proportional to its outer surface. Starting with a rapid overview on other methods to come up with this task, the attention in principally oriented to surface estimation by means of optical scanning. A preliminary test session has been carried out and two main issues arose. The first one is related to resolution and accuracy: due to pieces small dimensions and details, high performances are required to achieve valid results. The second and principal issue is related to the high reflectivity of pieces, even before electroplating. With the aim of avoiding the use of matting paint (which is difficult to remove), the attention has been focused on commercial solution dedicated to jewellery and dentistry fields. Three devices (based on white and blue LED structured light) have been tested on high reflective and specular pieces. From the analyses, only the one based on blue LED technology was able to retrieve high reflective surfaces without matting. Minor issues arose in case of specular surface. The device has been considered suitable for the task.

Keywords: 3D optical scanners | 3D reconstruction | Blue LED structured light | Galvanic | Reverse engineering

Abstract: Blind and visually impaired people are mostly excluded in enjoying visual artwork yet. Even if the effectiveness of tactile supports has been proven in previous studies, these are difficult to realize, since they are commonly handmade. In this paper, a set of computer-aided interactive tools for a semi-automatic reconstruction of tactile bas-relieves is proposed. Starting from the digital picture of a painting, this set make it possible to retrieve a 2.5D reconstruction of a scene in the form of flat-layered bas relief, which means that the scene is reconstructed solely by means of geometric primitives such planes, cylindrical surfaces, conical surfaces and generic (curve) surfaces. Tools have been specifically thought to obtain tactile bas-relieves of architectural scenes. Unlike typical handmade crafting, the proposed tools do not require specific user skills or training. In fact, user is only asked to select points (i.e., to detect a vanishing point) or segments of the picture to obtain a specific surface. Tools have been designed, optimized, and adopted to realize the tactile bas-relief of the painting Piazza San Francesco (unknown artist, Museo Civico di Arte Antica - Pistoia), within the research activities related to ARTE project (Augmented Readability Tactile Exploration), co-founded by Cassa di Risparmio di Pistoia e Pescia.

Keywords: Blind | Shape from single image | Tactile bas-relief

Abstract: The treatment of burn scars is a much discussed and sensitive topic because an improper therapy can have a significant impact on the quality of people's lives. To accurately assess both the health of scars and the outcomes of treatment, the medical evaluation should be based on objective measurements of progression over time. To overcome the limitations of subjective assessment is to leverage, 3D scanning technologies can be used to acquire topological information about the lesions and extract a set of relevant statistical parameters describing them. Accordingly, the present work aims at addressing both efficiency and reliability of a preliminary method based on the objective investigation of the surface topography of burn scars by applying it on several patients of the Meyer Children's Hospital burns department. A commercial 3D scanner is used to acquire 3D data relative to the scars of five patients. By applying a method based on the computational analysis of scan data, a significant number of roughness-related parameters are retrieved. This information is used to create a coherent dataset that allows the severity of burn scars to be inferred objectively. The developed method facilitates the evaluation of treatment efficacy by assessing wound healing during follow-up visits.

Keywords: 3D scan | Burn scar | Surface roughness

Abstract: According to previous research, shore 40 A casting silicone is currently one of the more suitable materials for simulating the physical behavior of the airways in medicine simulation. This is essential to attain high-fidelity manikins that can perfectly mimic the simulated anatomic region, not just geometrically, but also in terms of haptic feedback. Due to the geometrical complexity of the tracheo-bronchial tree, mold design is a difficult and time-consuming process. An interactive modeling procedure for modeling mold parts for tracheo-bronchial tree casting is proposed in this paper, with the purpose of reducing modeling time without compromising quality. Following the definition of a standard modeling procedure, this was implemented in the Matlab language by using an IGES and STL editing toolbox. By using the interactive procedure it is possible to reduce the time required for virtual modeling from several hours to less than 1 min. Given this preliminary result, the proposed procedure will be further tested and developed in the near future, with the possibility of automating other lower airway modeling steps, such as vent generation and mounting holes/pins.

Keywords: 3D modelling | Airway simulation | Interactive design | Mold casting

Abstract: 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

Abstract: In the biomedical field, high-fidelity simulation plays a fundamental role for medical and surgical staff as it allows them to simulate real scenarios from everyday clinical practice. The availability of patient-specific pathological models allows doctors to simulate surgical procedures before entering the operating room, thus reducing the risks associated with surgery. Such models are also employed in medical training to enhance the experience of trainees by confronting them with possible real-life emergency scenarios. To obtain a strict correspondence between simulator and reality - both in terms of geometry and haptic feedback - important decisions must be taken from the beginning of the design phase. High fidelity is a fundamental requirement of the simulators, since the design phase of the anatomical model, for what concerns geometries and materials. In this paper, a preliminary study for the development of a paediatric tracheal simulator is presented. This study is focused on the definition of some general geometric parameters and of the material composing the simulator. Mechanical characteristics of the trachea are investigated to identify a set of materials able to reproduce a realistic haptic feedback of the simulator. Materials are chosen in relation with the technological process that will be used for the simulator manufacturing: additive manufacturing or mould casting. To test the various materials, specimens are created and submitted to the judgement of a specialized medical team. The results showed Shore 40A silicone with a 1.75 mm wall-thickness value to be the best compromise for reproducing the haptic feedback of the trachea.

Keywords: 3D printing | Airway simulation | Haptic feedback | Paediatric trachea | Soft tissue modelling

Abstract: 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

Abstract: The LIFE SNEAK project, started in September 2021, aims at the reduction of noise in densely populated urban areas where noise and vibrations produced by the tram overlap with noise produced by road traffic. Applicative measures will be designed and tested in a pilot case of the city of Florence, such as low-noise and vibration surfaces, with life cycle costs comparable to those of traditional surfaces, and measures to reduce tram noise aiming to obtain substantial reductions in noise and annoyance. Referring to tram noise, in the first phase of the project, specific attention has been dedicated to the state-of-the-art analysis concerning possible measures to perform noise reduction with specific attention to noise due to wheel-rail contact and “squeal noise” phenomena that mainly occur in urban environments close to curves with small radius. In this paper, the results of the state-of-the-art analysis are presented with particular attention to the use of sound-absorbing panels to be applied on the tram (bogie skirts).

Keywords: Acoustic noise | Acoustic wave absorption | Life cycle | Noise pollution | Sound insulating materials | Trolley cars

Abstract: Purpose: To determine the targeting accuracy of brain radiosurgery when planning procedures employing different MRI and MRI + CT combinations are adopted. Materials and method: A new phantom, the BrainTool, has been designed and realized to test image co-registration and targeting accuracy in a realistic anatomical situation. The phantom was created with a 3D printer and materials that mimic realistic brain MRI and CT contrast using a model extracted from a synthetic MRI study of a human brain. Eight markers distributed within the BrainTool provide for assessment of the accuracy of image registrations while two cavities that host an ionization chamber are used to perform targeting accuracy measurements with an iterative cross-scan method. Two procedures employing 1.5 T MRI-only or a combination of MRI (taken with 1.5 T or 3 T scanners) and CT to carry out Gamma Knife treatments were investigated. As distortions can impact targeting accuracy, MR images were preliminary evaluated to assess image deformation extent using GammaTool phantom. Results: MR images taken with both scanners showed average and maximum distortion of 0.3 mm and 1 mm respectively. The marker distances in co-registered images resulted below 0.5 mm for both MRI scans. The targeting mismatches obtained were 0.8 mm, 1.0 mm and 1.2 mm for MRI-only and MRI + CT (1,5T and 3 T), respectively. Conclusions: Procedures using a combination of MR and CT images provide targeting accuracies comparable to those of MRI-only procedures. The BrainTool proved to be a suitable tool for carrying out co-registration and targeting accuracy of Gamma Knife brain radiosurgery treatments.

Keywords: 3D MR image distortion phantom | 3D printing | Brain phantom | MR/CT imaging quality control | Stereotactic radiosurgery accuracy

Abstract: 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

Abstract: Disruptive 3D technologies, such as reverse engineering (RE) and additive manufacturing (AM), when applied in the medical field enable the development of new methods for personalized and non-invasive treatments. When referring to the monitoring of pectus excavatum, one of the most common thoracic malformations, 3D acquisition of the patient chest proved to be a straightforward method for assessing and measuring chest deformation. Unfortunately, such systems are usually available in a dedicated facility, can be operated only by specialized doctors with the support of engineers and can be used only with patients on site. It is therefore impossible to perform any routine check-up when the patient is unable to reach the outpatient clinic. The COVID19 pandemic situation has placed even greater restrictions on patient mobility, worsening this problem. To deal with this issue, a new low-cost portable optical scanner for monitoring pectus excavatum is proposed in this work. The scanner, named Thor 2.0, allows a remote diagnostic approach, offering the possibility to perform routine check-ups telematically. Usability tests confirmed the user-friendly nature of the devised system. The instrument was used at the Meyer Children’s Hospital (Florence, Italy) chest-malformations center to treat PE patients. The performed measurements proved to be in line with the current state of the art.

Keywords: Handheld scanner | Intel RealSense | Optical chest index | Pectus excavatum | Telemedicine | Usability test | Vacuum bell

Abstract: 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

Abstract: In the region of the cultural patrimony, operators use high-resolution orthophotos of paintings for the restoration, monitoring and electronic recording and exhibition purposes. Unfortunately, artworks that are to be restored and/or shown in digital museums are painted on canvas that are far from perfectly planar. Professional documents surrounding an artwork to be preserved in digital collections or museums can therefore be enhanced with information relating to the paintings' 3D structure. This paper proposes both the design of a portable low-cost device that enables the acquisition of 3D geometry of painting and the procedure for triangulation of 3D data. This process uses a set of fiducial markers to set and continuously control the mutual orientation of the laser source and the camera and works accordingly to the principle of laser-camera triangulation.

Keywords: 3D Laser Scanner | Cultural Heritage | Marker Detection | Pose Estimation | Reverse Engineering

Abstract: In the field of cultural heritage, operators make use of high resolution orthophotos of paintings both for purposes related to restoration and monitoring of art pieces and for realizing online documentations and exhibitions. Unfortunately, artworks to be restored and/or presented in digital museums are painted on canvas which are far to be perfectly planar. Therefore, technical documentation accompanying an artwork to be stored in digital archives or museums can be enriched by information related to the 3D shape of the canvas. In this paper, both the design of a portable low-cost device that allows the acquisition of the 3D geometry of the painting and a procedure to triangulate 3D data are proposed. Such a procedure, working using the principle of laser-camera triangulation, is based on the use of a set of fiducial markers to set and continuously control the reciprocal orientation of the laser source and of the camera.

Keywords: 3D laser scanner | Cultural heritage | Marker detection | Pose estimation | Reverse engineering

Abstract: In the fashion field, the use of electroplated small metal parts such as studs, clips and buckles is widespread. The plate is often made of precious metal, such as gold or platinum. Due to the high cost of these materials, it is strategically relevant and of primary importance for manufacturers to avoid any waste by depositing only the strictly necessary amount of material. To this aim, companies need to be aware of the overall number of items to be electroplated so that it is possible to properly set the parameters driving the galvanic process. Accordingly, the present paper describes a simple, yet effective machine vision-based method able to automatically count small metal parts arranged on a galvanic frame. The devised method, which relies on the definition of a rear projection-based acquisition system and on the development of image processing-based routines, is able to properly count the number of items on the galvanic frame. The system is implemented on a counting machine, which is meant to be adopted in the galvanic industrial practice to properly define a suitable set or working parameters (such as the current, voltage, and deposition time) for the electroplating machine and, thereby, assure the desired plate thickness from one side and avoid material waste on the other.

Keywords: Electro-deposition industry | Image analysis | Item counting device | Machine vision

Abstract: 3D reconstruction of human anatomy from cross-sectional imaging has recently gained increasing importance in several medical fields thus designating the 3D bones reconstruction accuracy, critical for the success of the whole surgical intervention. The 3D anatomic model quality depends on the quality of the reconstructed image, on the quality of the images segmentation step and on the error introduced by the iso-surface triangulation algorithm. The influence of image processing procedures and relative parametrization has been largely studied in the scientific literature; however, the analysis of the direct impact of the quality of the reconstructed medical images is still lacking. In this paper, a comparative study on the influence of both image reconstruction algorithm (standard and iterative) and applied kernel is reported. Research was performed on the 3D reconstruction of a pig tibia, by using Philips Brilliance 64 CT scanner. At the stage of scanning and at the stage of 3D reconstruction, the same procedures were followed, while only image reconstruction algorithm and kernel were changed. The influence of such selection on the accuracy of bone geometry was assessed by comparing it against the 3D model obtained with a professional 3D scanner. Results show an average error in reconstructing the geometry of around 0.1 mm with a variance of 0.08 mm. The presented study highlights new opportunities to control the deviations on the geometry accuracy of the bones structures at the stage of cross sectional imaging generation.

Keywords: 3D model reconstruction | Accuracy | Computed tomography | Kernel reconstruction

Abstract: Within the T-VedO project, financed by Tuscany Region, the Reverse Engineering and Virtual Prototyping Lab team of the Department of Industrial Engineering of Florence (Italy) developed a number of methods for the semiautomatic generation of digital 2.5D models starting from paintings. Once such models are prototyped, they can be used to enhance visually impaired people tactile experience of artworks. Such methods, combined into a systematic procedure, allow to solve most of the typical problems arising when dealing with artistic representation of a painted scene. The present paper presents both an overview of the proposed procedure, including most recent updates, and the results obtained for a selected number of artworks of the Florentine Renaissance.

Keywords: 2.5D models | 3D Reconstruction | CAD

Abstract: With the aim of retrieving 3D surfaces starting from single shaded images, i.e. for solving the widely known shape from shading problem, an important class of methods is based on minimisation techniques where the expected surface to be retrieved is supposed to be coincident with the one that minimise a properly developed functional, consisting of several contributions. Despite several different contributes that can be explored to define a functional, the so called 'smoothness constraint' is a cornerstone since it is the most relevant contribute to guide the convergence of the minimisation process towards a more accurate solution. Unfortunately, in case input shaded image is characterised by areas where actual brightness changes rapidly, such a constraint introduces an undesired over-smoothing effect for the retrieved surface. The present work proposes an original strategy for avoiding such a typical over-smoothing effect, with regard to the image regions in which this is particularly undesired such as, for instance, zones where surface details are to be preserved in the reconstruction. The proposed strategy is tested against a set of case studies and compared with other traditional SFS-based methods to prove its effectiveness.

Keywords: 3D model | Minimisation | SFS | shape from shading | Smoothing | Smoothness constraint | variational approach

Abstract: During sintering, porcelain changes its phase composition as well as its physical and mechanical properties. The most evident effect of these transformations is a significant change of shape, which is a combination of shrinkage and pyroplastic deformations, caused by softening. Both of these phenomena are induced by temperature, which is on its turn influenced by several variable factors that are difficult to predict. Especially for products manufactured in large scale, the resulting shape of artefacts may significantly vary even among the same batch. Consequently, for companies demanding high quality standard, this variability entails a high number of rejected products. For this reason, the present work aims at investigating the amount of variation introduced by firing process for an actual industrial product, independently from other (more or less) known variation sources such as the ones related to materials and forming processes. This could help process engineers to focus their attention when trying to improve the quality of final products.

Keywords: Geometric characterization | Porcelain manufacturing | Reverse Engineering | Scattering analysis

Abstract: Shape from shading (SFS) denotes the problem of reconstructing a 3D surface, starting from a single shaded image which represents the surface itself. Minimization techniques are commonly used for solving the SFS problem, where the objective function is a weighted combination of the brightness error, plus one or more terms aiming to obtain a valid solution. We present a regularized quadratic penalty method where quadratic penalization is used to adaptively adjust the smoothing weights, and regularization improves the robustness and reliability of the procedure. A nonmonotone Barzilai–Borwein method is employed to efficiently solve the arising subproblems. Numerical results are provided showing the reliability of the proposed approach.

Keywords: Barzilai–Borwein method | quadratic penalty methods | quadratic regularization | Shape from shading

Abstract: During manufacturing, porcelain whiteware changes its shape due to the sintering process. For this reason, leader companies in the field of ceramics apply strict controls on final products in order to reach high quality standards. Typically, three quality parameters are considered: drop of the bottom, bending of the rim and roundness. To date, the assessment of such parameters is still based on visual inspections and manual measurements. In the present paper, authors propose a new quality assessment procedure based on reverse engineering (RE), able to measure the most relevant quality parameters in an effective, reliable and repeatable way.

Keywords: 3D model | 3D reconstruction | 3D scanning | measurement | porcelain | porcelain tableware | quality control | quality parameters | reverse engineering | whiteware

Abstract: The stylistic design of new industrial products often starts from shaded handmade sketches which, usually, need to be converted into 3D digital models by using CAD software packages for the subsequent design phases. This conversion often represents the bottleneck of the whole development process. Shape from Shading (SFS), which attempts to recover the 3D geometry of an object starting from a single shaded representation, is potentially capable of speeding-up the 3D conversion. However, existing approaches prove to be extremely unstable and error prone mainly due to the under-determination of the SFS problem. In order to increase the performance of shading based reconstruction authors propose a step-by-step variational-based approach. In particular, the problem is solved into multiple steps, each one providing the initialization for the following, so that the solution gradually converges towards the final surface. Tested against a set of case studies, the method proved its effectiveness.

Keywords: 3D design | Computer aided design | Numerical optimization | Shape from shading | Stylistic content | Variational approach

Abstract: Minimization techniques are widely used for retrieving a 3D surface starting from a single shaded image i.e., for solving the shape from shading problem. Such techniques are based on the assumption that expected surface to be retrieved coincides with the one that minimize a properly developed functional, consisting of several contributions. Among the possible contributes defining the functional, the so called "smoothness constraint" is always used since it guides the convergence of the minimization process towards a more accurate solution. Unfortunately, in areas where actually brightness changes rapidly, it also introduces an undesired over-smoothing effect. The present work proposes two simple yet effective strategies for avoiding the typical over-smoothing effect, with regards to the image regions in which this effect is particularly undesired (e.g., areas where surface details are to be preserved in the reconstruction). Tested against a set of case studies the strategies prove to outperform traditional SFS-based methods.

Keywords: 3D model | Minimization | Shape from shading | Smoothing | Smoothness constraint | Variational approach

Abstract: Cultural heritage is often not accessible to visually impaired and blind people, hardly ever when dealing with two-dimensional artworks like, for instance, paintings. In fact, despite tactile reproductions of 3D works of art such as sculptures or architectural models are quite common, a real barrier between blind people and pictorial artworks still exists, obviously due to their intrinsic 2D format. The translation of paintings into bas-relieves is recognized to be one of the most effective ways for breaking down such a barrier, thus allowing a sensible improvement in blind people's accessibility to this kind of works of art. Moving from these considerations, in this work the authors want to provide a bird's eye view on a new methodology for the semi-automatic generation of tactile 3D models starting from paintings, in particular those characterized by single-point perspective. The proposed method relies on an interactive Computer-based modelling procedure, which is conceived to be simple and effective to use. The procedure, which has been implemented into a prototypal software package, has been effectively used to 'translate' a set of paintings from the Italian Renaissance.

Abstract: In the last decades several computer-based procedures have been devised with the aim of speeding up the 3D reconstruction from a single image in the form of bas-relief. At the same time, the use of rapid prototyping (RP) technology considerably spread enabling quick manufacture of 3D products directly from 3D modelling systems. The present paper presents a few consideration about different possible strategies for bas-reliefs manufacturing by using the main RP techniques (stereolithography (SLA), selective laser sintering (SLS), fused deposition modeling (FDM) and Polyjet/Multi-jet technology). A practical example is used for discussing pros and cons of the different alternatives. © (2014) Trans Tech Publications, Switzerland.

Keywords: Artistic surfaces | Bas-relief | Rapid prototyping techniques

Abstract: Design of new industrial objects characterized by high stylistic content often starts from sketches or images of the product to be, subsequently, represented in a 3D digital form by using CAD software. To speed up this phase, a number of methods for automatic or semi-automatic translation of sketches or images into a 3D model have been devised all over the world also for reverse engineering purposes. When the image shading is a crucial information for recovering the final 3D shape, Fast Marching is recognized to be among the best method to date, especially for frontally illuminated scenes. Unfortunately, such a method cannot be directly applied when object illumination in the considered image is oblique. The present work is aimed to propose a simple, but effective, approach for recovering 3D shape of objects starting from single side illuminated scenes i.e. for solving non-eikonal SFS problems. Tested against a set of case studies, the method proved its effectiveness. © (2014) Trans Tech Publications, Switzerland.

Keywords: Digital design | Fast marching | Intelligent manufacturing | Oblique illumination | Shape from shading

Abstract: Commonly used to produce the visual effect of full 3D scene on reduced depth supports, bas relief can be successfully employed to help blind people to access inherently bi-dimensional works of art. Despite a number of methods have been proposed dealing with the issue of recovering 3D or 2.5D surfaces from single images, only a few of them explicitly address the recovery problem from paintings and, more specifically, the needs of visually impaired and blind people. The main aim of the present paper is to provide a systematic method for the semi-automatic generation of 2.5D models from paintings. Consequently, a number of ad hoc procedures are used to solve most of the typical problems arising when dealing with artistic representation of a scene. Feedbacks provided by a panel of end-users demonstrated the effectiveness of the method in providing models reproducing, using a tactile language, works of art otherwise completely inaccessible.

Keywords: 2.5D model | Minimization techniques | Shape From Shading | Tactile model

Abstract: In the last years the development of interactive Computer-based methods for building virtual and physical 2.5D models from single shaded images faced with an exponential growth. In particular, a wide range of methods based on image processing-based procedures and on Shape From Shading (SFS) can be documented. On the basis of the most favorable techniques devised in literature, the present work describes an improved interactive method capable of retrieving 2.5D models using image shading information. The pro-posed method performs a SFS-based reconstruction where (1) the overall geometry of the expected surface is first recovered and (2) the final 2.5D reconstruction is obtained by minimizing a suitable functional using the rough surface as an initialization function. The method improves previous interactive works by introducing a novel two-step rough surface recovery and a new definition of a functional to be minimized for solving the SFS problem. Tested against a set of case studies the proposed method proves to be effective in providing 2.5D models. © 2014 Science Publications.

Keywords: 2.5D model | Image processing | Interactive reconstruction | Minimization | Shape from shading

Abstract: Design of products characterized by high stylistic content and organic shapes in the form of bas-relief (e.g. fashion accessories, commemorative plaques and coins) is traditionally performed starting from handmade drawings or photographs that are manually reproduced by highly skilled craftsmen such as sculptors and engravers and finally digitized by means of 3D scanning. Several Computer-based procedures have been devised with the aim of speeding up this process, which is considerably time consuming, subjective and costly; these are mainly based on image processing techniques such as embossing, enhancement, histogram equalization or dynamic range, also implemented in CAD-based commercial software. However, these approaches are characterized by several limitations preventing them from providing a "correct" final geometry. In view of that, the present work describes a novel method for the creation of digital bas-reliefs from a single image using a Shape From Shading (SFS) based approach with interactive initialization. Image processing-based techniques and minimization SFS methods are first used in order to retrieve a rough version of the objective surface; successively, this is used as initialization for the final reconstruction algorithm. Tested on a set of case studies, the method proved to be effective in providing satisfactory digital bas-relief from single images. © 2013 © 2013 CAD Solutions, LLC.

Keywords: digital bas-relief | image processing | shape from shading | shape retrieval

Abstract: Minimisation techniques are commonly adopted methodologies for retrieving a 3D surface starting from its shaded representation (image), i.e., for solving the widely known shape from shading (SFS) problem. Unfortunately, depending on the imaged object to be reconstructed, retrieved surfaces often results to be completely different from the expected ones. In recent years, a number of interactive methods have been explored with the aim of improving surface reconstruction; however, since most of these methods require user interaction performed on a tentative reconstructed surface which often is significantly different from the desired one, it is advisable to increase the quality of the surface, to be further processed, as much as possible. Inspired by such techniques, the present work describes a new method for interactive retrieving of shaded object surface. The proposed approach is meant to recover the expected surface by using easy-to-set boundary conditions, so that the human-computer interaction primarily takes place prior to the surface retrieval. The method, tested on a set of case studies, proves to be effective in achieving sufficiently accurate reconstruction of scenes with both front and side illumination. © 2013 Inderscience Enterprises Ltd.

Keywords: Boundary conditions | Computational vision | Human-computer interaction | Minimisation techniques | SFS | Shape from shading

Abstract: The research and development of new conservation materials and instrumentation and the integration of contemporary science into the discipline are of fundamental importance in formulating best practices in conservation and preserving cultural heritage assets. With this goal in mind in November 2011, the IMAT project (Intelligent Mobile Accurate Thermo-Electrical mild heating device) was launched under the European Commission's 7th Framework Program (FP7) for research. During the three-year length of the project, coordinated by the University of Florence, a European consortium of researchers representing expertise in conservation, nanotechnology, and thermo-electrical engineering will develop nanotechnology for the IMAT devices specifically designed for highly accurate mild heating in conservation of artworks and other cultural heritage assets. © 2012 Springer-Verlag Berlin Heidelberg.

Keywords: conservation | IMAT | mild heating | nanotubes