1,721,041 research outputs found
Large yacht hull measurement by integrating optical scanning with mechanical tracking-based methodologies
No full textIn the shipbuilding industry, the manufacturing of large yacht hulls is a complex process. Metal hulls are traditionally manufactured by welding pre fabricated large steel panels to form the external superstructure. A surface finishing process is then carried out in order to obtain a final target surface having a smooth curvature. The methodologies manly rely on manual processes based on the measurement of the as built hull shape through simple testing instrumentation. Well-experienced workers are required, and a great amount of time is usually wasted, thus affecting the overall shipyard competitiveness.
This paper introduces a methodology for automating the measurement process of as built hull yacht shapes. The methodology, which is based on the integration of a robotic system with an optical scanner, provides accurate non contact 3D full field measurements of the hull surface. The placement of the robotic system around the hull shape is determined by a laser total station thus allowing the automatic multi view data registration into a common reference frame. The proposed approach represents the basis for the automation of the whole surface finishing process of large yacht hulls. In this paper, the methodology has been tested by measuring a large broadside area of a 59 m hull assembled within a shipyard
Automatic Alignment of Multiple Point Clouds by Image Processing and 3D Data Matching
No full textIn recent years, various methodologies of reverse engineering have been proposed with the aim at creating CAD models from digitization of target objects using optical sensors. Traditionally, the acquisition of 3D geometrical data includes crucial tasks, such as planning scanning strategies and aligning different point clouds by many alternative methodologies which differ for user interaction levels and costs. This paper describes a technology to acquire free form surfaces by combining a 3D vision system and a fully automatic point clouds alignment procedure based on fiducial marker recognition. The aim is to create accurate and complete digital representations of physical objects, even those presenting a few morphological singularities, in a very short time and with minimal human intervention. The technology has been tested acquiring target objects with complex shape
APPARECCHIATURA E PROCESSO DI FABBRICAZIONE DI DISPOSITIVI DENTALI ORTODONTICI E/O PROTESICI
No full textIl brevetto riguarda un'apparecchiatura e un processo di fabbricazione di dispositivi dentali ortodontici e/o protesici, in particolare di apparecchi ortodontici per il riposizionamento dentale incrementale, ma impiegabile anche per la fabbricazione di altri dispositivi dentali quali ad esempio bite, guide occlusali, dispositivi protesici, guide chirurgiche e così via. In particolare il brevetto si riferisce alla realizzazione di un'apparecchiatura di fabbricazione di dispositivi dentali ortodontici o protesici completamente automatizzata. Il brevetto si colloca nel campo dell'ortodonzia e, più nello specifico, nel campo della progettazione di trattamenti ortodontici facenti impiego di apparecchi ortodontici del tipo trasparente o invisibile
Computer-aided modeling of 3D maxillofacial tissues through multi-modal imaging
No full textRecent developments in digital imaging techniques have allowed a wide spread of three-dimensional methodologies based on capturing anatomical tissues by different approaches, such as cone-beam computed tomography, three-dimensional photography and surface scanning. In oral rehabilitation, an objective method to predict surgical and orthodontic outcomes should be based on anatomical data belonging to soft facial tissue, facial skeleton and dentition (maxillofacial triad). However, none of the available imaging techniques can accurately capture the complete triad. This article presents a multi-modal framework, which allows image fusion of different digital techniques to create a three-dimensional virtual maxillofacial model, which integrates photorealistic face, facial skeleton and dentition. The methodology is based on combining structured light surface scanning and cone-beam computed tomography data processing. The fusion procedure provides multi-modal representations by aligning different tissues on the basis of common anatomical constraints
Validation of a No-Contact CMM System for Fast and Accurate 3D Shape Measurements
No full textThe measurement process of three-dimensional shapes has recently assumed a relevant role in various industrial applications due to its wide field of application such as reverse engineering or coordinate metrology in dimensional control. The acquisition of 3D geometrical data generally requires three main steps: planning the number and the right sequence of all the range scans, acquiring the single data sets and aligning the collected data in a common reference frame. The overall measurement accuracy directly depends on the planned strategy, the sensor precision and the alignment methodology used. Among these, the point cloud alignment phase represents the task having the main influence on the reliability of the measurement process and on required time.
This paper describes an integration between a 3D stereo vision system and 5 motorized axes with the aim at the definition of a no-contact Coordinate Measurement Machine (CMM) system for fast and accurate digital representations of target objects with minimum human intervention. An automatic alignment methodology, based on a calibration procedure of the vision system with respect to the 5 axes, allows rapid and high-precision 3D shape measurements with minimum human intervention
Epipolar geometry and structured light for reverse engineering of free form surfaces
No full textThis paper presents a 3D optical digitiser based on an active stereo vision aproach. The system is composed of a digital camera, a multimedia projector and software to control the hardware and process the images. The proposed solution integrates an active coded light method with a photogrammetric procedure in order to allow the acquisition of complex surfaces. In the work, experimental tests have been conducted with a nominal model and styling components of two-wheeler vehicles. The measurement process and the experimental results have been analysed to verify usability and accuracy of the methodology
Una Metodologia per la Progettazione di Impianti Dentali Tramite Digitalizzazione 3D
No full textL’ancoraggio di protesi dentarie ad impianti dentali osteointegrati è ormai una procedura ben definita nell’ambito del trattamento clinico di patologie del sistema masticatorio. Negli ultimi anni, lo sviluppo di sistematiche CAD/CAM ha permesso di uniformare la procedura di progettazione e realizzazione di impianti dentali, garantendo il miglioramento della qualità funzionale della protesi. Tuttavia, un aspetto critico della procedura implantologica riguarda l’individuazione della posizione dell’impianto all’interno dell’arcata dentale.
Questo lavoro presenta una metodologia per la progettazione implantologica basata sull’utilizzo combinato di un sistema ottico per la scansione 3D di modelli dentali, e di un applicativo CAD dedicato alla modellazione di strutture protesiche
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