6 research outputs found

    Utilisation d'un modele d'objet en reconstruction 3D

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    Nous décrivons un système de reconstruction 3D pour la tomographie en transmission intégrant l'algorithme RADON développé au LETI et l'utilisation de connaissances a priori sous forme d'un modèle 3D de l'objet à reconstruire. Les objets que nous cherchons à reconstruire sont naturellement bien contrastés. Le modèle markovien choisi nous permet de mieux préserver les frontières naturelles de l'objet alors que les méthodes classiques ont tendance à lisser les transitions

    X-Ray Cone Beam Tomography with Two Tilted Circular Trajectories

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    Recently 3-D cone-beam tomography has become of interest for the nondestructive evaluation of advanced materials. The main field of application in nondestructive testing is the evaluation of structural ceramics. Study of such materials implies high density resolution and high sensitivity to cracks. In fact, with a single circular source trajectory, when the cone-beam aperture increases, density is underestimated and cone shaped artifacts may appear at interfaces in the sample even at relatively small aperture [1–3]. These artifacts limit the thickness we can examine with a planar source trajectory. To maintain optimal reconstruction accuracy with a circular source trajectory, the angular aperture must remain within ±10°. However Kudo and Saito [4] showed that this limit can be slightly overcome by using a special interpolation of the shadow area. But to examine greater thicknesses and to maintain resolution, we must widen the cone-beam aperture thereby decreasing accuracy. To overcome these aperture limitations, Tuy [5] introduced the double circular source trajectory idea.</p

    Recentes evolutions de la tomographie 3D en geometrie conique

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    La tomographie 3D en géométrie conique définit un mode d'acquisition performant. Notre analyse théorique de la reconstruction repose sur le calcul et l'inversion de la dérivée première de la transformée de Radon. Nous décrivons ici les récentes évolutions de nos travaux, à savoir le développement du logiciel RADON et son optimisation, l'étude d'un protocole d'analyse de la FTM et l'extension de notre algorithme à deux trajectoires d'acquisition circulaires inclinées

    Utilisation d'un modele d'objet en reconstruction 3D

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    communication a : conference of the research and studies group on signal processing, Juan-les-Pins (FR), 16-20 Sep 1991SIGLEAvailable at INIST (FR), Document Supply Service, under shelf-number : RM 1097 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

    MASSIF-1: a beamline dedicated to the fully automatic characterization and data collection from crystals of biological macromolecules

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    International audienceMASSIF-1 (ID30A-1) is an ESRF undulator beamline operating at a fixed wavelength of 0.969 angstrom (12.8 keV) that is dedicated to the completely automatic characterization of and data collection from crystals of biological macromolecules. The first of the ESRF Upgrade MASSIF beamlines to be commissioned, it has been open since September 2014, providing a unique automated data collection service to academic and industrial users. Here, the beamline characteristics and details of the new service are outline
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