1,721,182 research outputs found
A RGB-D based instant body-scanning solution for compact box installation
No full textBody scanning presents unique value in delivering the first digital asset of a human body thus resulting a fundamental device for a range of applications dealing with health, fashion and fitness. Despite several body scanners are in the market, recently depth cameras such as Microsoft Kinect® have attracted the 3D community; compared with conventional 3D scanning systems, these sensors are able to capture depth and RGB data at video rate and even if quality and depth resolution are not optimal for this kind of applications, the major benefit comes from the overall acquisition speed and from the IR pattern that allows poor lighting conditions optimal acquisition. When dealing with non-rigid bodies, unfortunately, the use of a single depth camera may lead to inconsistent results mainly caused by wrong surfaces registration. With the aim of improving existing systems based on low-resolution depth cameras, the present paper describes a novel scanning system for capturing 3D full human body models by using multiple Kinect® devices in a compact setup. The system consists of an instantaneous scanning system using eight depth cameras, appropriately arranged in a compact wireframe. To validate the effectiveness of the proposed architecture, a comparison of the obtained 3D body model with the one obtained using a professional Konica Minolta Range Seven 3D scanner is also presented and possible drawbacks are hinted at
Comparison of Mesh Simplification tools in a 3D Watermarking framework
No full textGiven a to-be-watermarked 3D model, a transformed domain analy-sis is needed to guarantee a robust embedding without compromising the visual quality of the result. A multiresolution remeshing of the model allows to repre-sent the 3D surface in a transformed domain suitable for embedding a robust and imperceptible watermark signal. Simplification of polygonal meshes is the basic step for a multiresolution remeshing of a 3D model; this step is needed to obtain the model approximation (coarse version) from which a refinement framework (i.e. 3D wavelet analysis, spectral analysis, ...) able to represent the model at multiple resolution levels, can be performed. The simplification algo-rithm should satisfy some requirements to be used in a watermarking system: the repeatability of the simplification, and the robustness of it to noise or, more generally, to slight modifications of the full resolution mesh. The performance of a number of software packages for mesh simplification, including both commercial and academic offerings, are compared in this survey. We defined a benchmark for testing the different software in the watermarking scenario and reported a comprehensive analysis of the software performances based on the geometric distortions measurement of the simplified versions
Computer Aided Design Tool for GT Ventilation System Ductworks
No full textThe design of gas turbine ventilation systems (VSs) is a lengthy and tedious process, often requiring weeks to refine a single design concept and by additional time to manufacture it. This is particularly true when dealing with structural design since the typical approach followed by main worldwide manufacturing companies is to outsource finite elements analysis and, often, the 3d modelling phase itself. Moreover, the structural design process is iterative: the modeling and finite elements analysis steps are repeated several times whenever a new VS has to be produced. Accordingly, speeding-up the structural design phase is today a crucial issue for gas turbine sector. Keeping the above objective in mind, the present paper proposes a CAD-based tool, implemented in a commercial 3D CAD software package (SolidWorks), supporting and partly automating the complex structural VS design process. The solution suggested in this work consists of the design and implementation of a SolidWorks add-in, called DuctWorks, developed by using C# programming language. Differently from commercially available solutions, the proposed tool is specifically thought keeping in mind the necessity of performing a final structural assessment, which is of utmost importance given the considerable dimensions and stresses this kind of VS are subject to in the specific field of GT and energy production industry. Tested against a set of case studies, DuctWorks proved to be effective in allowing designers to accelerate the ventilation systems design process with excellent results when compared with the traditional design process
Computer Aided Design Tool for GT Ventilation System Ductworks
No full textThe proper design of a ventilation system (VS) is an important requirement in the Gas Turbine (GT) and energy production industry in general. In fact, ventilation systems are designed to provide a continuous source of cooling air so as to: remove heat and maintain the air temperature in the compartment below the operating limit; prevent the accumulation of hazardous gases; preserve a constant and uniform airflow through the ducts, independently from the environmental conditions; avoid accidental dust and sand contamination in gas turbines, especially when these are located in regions prone to sandstorm conditions. When compared to typical Heating, Ventilating and Air Conditioning (HVAC) systems, the design of VSs results particularly challenging since many requirements, generally involving different engineering aspects such as fluid-dynamic, acoustic and structural, have to be fulfilled. Generally speaking, a VS is composed by a number of elements such as linear ducts, expansion joints, transition duct sections, elbows, outlets to the atmosphere, supports, saddles and brackets. Shape and dimensions of these elements may significantly vary depending on the kind of application. Basically, the elements may have circular/oval or rectangular/square section. In the first case, they are manufactured by employing calendaring process followed by welding. Otherwise, the component is realized by cutting and welding metal sheets. Elements are coupled by using bolted flanges or welded joints in order to obtain the entire VS ductwork
Statistical Shape Model: comparison between ICP and CPD algorithms on medical applications
Full text linkThe increasing availability of 3D anatomical models obtained from diagnostic images exploiting Reverse Engineering techniques allows the application of statistical analysis in the quantitative investigation of anatomical shapes variability. Statistical Shape Models are a well-established method for representing such variability, especially for complex forms like the anatomical ones. Not by chance, these models are widely used for medical applications, such as guiding segmentation of the diagnostic image and virtual reconstruction of incomplete anatomic region. The application of a statistical analysis on a set of shapes representing the same anatomical region essentially requires that shapes must be in correspondence, i.e. constituted by the same number of points in corresponding position. This work aims to compare two established algorithms, namely a modified version of the Iterative Closest Point and the non-rigid version of the Coherent Point Drift, to solve the correspondences’ problem in the construction of a Statistical Shape Model of the human cranium. The comparison is carried out on the models using the standard evaluation criteria: generalization, specificity and compactness. The modified version of the Iterative Closest Point delivers a better Statistical Shape Model in terms of generalization and specificity, but not for compactness, than the Coherent Point Drift-based model
Scene Acquisition with Multiple 2D and 3D Optical Sensors: A PSO-Based Visibility Optimization
Full text linkDesigning an acquisition system for 2D or 3D information, based on the integration of data provided by different sensors is a task that requires a labor-intensive initial design phase. Indeed, the definition of the architecture of such acquisition systems needs to start from the identification of the position and orientation of the sensors observing the scene. Their placement is carefully studied to enhance the efficacy of the system. This often coincides with the need to maximize the surfaces observed by the sensors or some other metric. An automatic optimization procedure based on the Particle Swarm Optimization (PSO) algorithm, to seek the most convenient setting of multiple optical sensors observing a 3D scene, is proposed. The procedure has been developed to provide a fast and efficient tool for 2D and 3D data acquisition. Three different objective functions of general validity, to be used in future applications, are proposed and described in the text. Various filters are introduced to reduce computational times of the whole procedure. The method is capable of handling occlusions from undesired obstacle in the scene. Finally, the entire method is discussed with reference to 1) the development of a body scanner for the arm-wrist-hand district and 2) the acquisition of an internal environment as case studies
3d printing of cardiac structures from medical images: an overview of methods and interactive tools
Full text linkThe percutaneous interventions in the treatment of structural heart diseases represent nowadays a viable option for patients at high risk for surgery. However, unlike during the traditional open heart surgery, the heart structures to be corrected are not directly visualized by the physician during the interventions. The interpretation of the available medical images is often a demanding task and needs specific skills i.e. clinical experience and complex radiological and echocardiographic analysis. The new trend for cardiovascular diagnosis, surgical planning and intervention is, today, mutually connected with most recent developments in the field of 3D acquisition, interactive modelling and rapid prototyping techniques. This is particularly true when dealing with complex heart diseases since 3D-based techniques can really help in providing an accurate planning of the intervention and to support surgical intervention. To help the research community in confronting with this new trend in medical science, the present work provides an overview on most recent approaches and methodologies for creating physical prototypes of patient-specific cardiac structures, with particular reference to most critical phases such as: 3D image acquisition, interactive image segmentation and restoration, interactive 3D model reconstruction, physical prototyping through additive manufacturing. To this purpose, first, recent techniques for image enhancement to highlight anatomical structures of interest are presented together with the current state of the art of interactive image segmentation. Finally, most suitable techniques for prototyping the retrieved 3D model are investigated so as to derive a number of criteria for manufacturing prototypes useful for planning the medical intervention
A Semi-Automatic Computer-Aided Method for Personalized Vacuum Bell Design
No full textPectus Excavatum, one of the most frequent chest wall deformities, is characterized by a depression of the sternum and costal cartilages. Patients with mild deformities are generally treated conservatively by using the so called Vacuum Bell (VB) i.e. a suction cup to be placed on the patient’s sternal region. Three different sizes, as well as a model fitted for young women, of VB are available on the market. Unfortunately, the variability of the surface to be treated, the possible asymmetry of the caved-in area and the prolonged use, can make the device uncomfortable and, in some cases, ineffective for the patient.
In order to cope with these issues, the present paper proposes a computer-aided method for customized vacuum bell design to be used by not-expert user, e.g. by medical staff. In particular, the present work entails the development of a system comprising: 1) a dedicated software capable of acquiring the 3D chest geometry - by using a low-cost range sensor, i.e. Kinect v2 - and of processing the point cloud so to generate NURBS surfaces of the chest; 2) a procedural CAD modelling of a personalized VB implemented within Siemens NX 11 CAD environment. Using the devised method, the medical staff is required only to use the 3D scanning system for acquiring the patient chest and to sketch, in a CAD-based interface, the boundary of the area to be treated. Once these tasks are performed, the system automatically builds the personalized VB model, ready to be manufactured
Metrological and Critical Characterization of the Intel D415 Stereo Depth Camera
Full text linkLow-cost RGB-D cameras are increasingly being used in several research fields, including human⁻machine interaction, safety, robotics, biomedical engineering and even reverse engineering applications. Among the plethora of commercial devices, the Intel RealSense cameras have proven to be among the most suitable devices, providing a good compromise between cost, ease of use, compactness and precision. Released on the market in January 2018, the new Intel model RealSense D415 has a wide acquisition range (i.e., ~160⁻10,000 mm) and a narrow field of view to capture objects in rapid motion. Given the unexplored potential of this new device, especially when used as a 3D scanner, the present work aims to characterize and to provide metrological considerations for the RealSense D415. In particular, tests are carried out to assess the device performance in the near range (i.e., 100⁻1000 mm). Characterization is performed by integrating the guidelines of the existing standard (i.e., the German VDI/VDE 2634 Part 2) with a number of literature-based strategies. Performance analysis is finally compared against the latest close-range sensors, thus providing a useful guidance for researchers and practitioners aiming to use RGB-D cameras in reverse engineering applications
A Preliminary Usability Assessment of a 3D Printable Orthosis Design System
No full textThe standard treatment for bones fractures entails the use of a tailor-made plaster cast which has several disadvantages: its weight generally causes discomfort, it cannot be taken off without breaking it, it can cause skin rashes and prevents ventilation of the treated area. Therefore, the application of traditional casts to orthopaedics patients does not represent, to date, the best option. To overcome the above-mentioned drawbacks, many strategies based on reverse engineering and additive manufacturing techniques have been proposed and proved to be a valid alternative for producing custom orthoses. Encouraged by the aforementioned results, the authors have developed a low-cost system (called Oplà), specifically dedicated to the hand-wrist-arm district of paediatric patients and capable of creating a 3D CAD model of the orthosis ready to be printed by using additive manufacturing techniques. Such a system comprises a 3D scanner, a control software and a semi-automatic CAD procedure t..
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