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Suche nach „[Gabriel] [Herl]“ hat 10 Publikationen gefunden
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    DigitalNachhaltigFraunhofer AWZ CTMTMaschinenbau und Mechatronik

    Zeitschriftenartikel

    Gabriel Herl, Jochen Hiller, A. Maier

    Scanning trajectory optimisation using a quantitative Tuybased local quality estimation for robot-based X-ray computed tomography

    Nondestructive Testing and Evaluation, vol. (Published 21 June 2020), no. 6

    2020

    DOI: 10.1080/10589759.2020.1774579

    Abstract anzeigen

    Robotic CT systems allow complex scanning trajectories. This work presents a workflow to automatically calculate optimised scanning trajectories for robotic CT systems. In particular, as a local quality estimation, this work introduces a quantitative measure to quantify local reconstruction quality based on the Tuy conditions. The proposed method is tested in two summation experiments using an STL model of a motorcycle. In both experiments, a trajectory is calculated using a quantitative Tuy-based local quality estimation and the reconstruction result is then compared to reconstructions using conventional scanning trajectories. The comparison results indicate that the proposed approach automatically finds trajectories that enable 3D reconstructions with high image quality using much less projection data, which allows a significant reduction of scanning time.

    DigitalNachhaltigFraunhofer AWZ CTMTMaschinenbau und Mechatronik

    Zeitschriftenartikel

    A. Stock, Gabriel Herl, T. Sauer, Jochen Hiller

    Edge-preserving compression of CT scans using wavelets

    Insight - Non-Destructive Testing and Condition Monitoring (The British Institute of Non-Destructive Testing), vol. 62, no. 6, pp. 345-351

    2020

    DOI: 10.1784/insi.2020.62.6.345

    Abstract anzeigen

    This work addresses the subject of efficient storage of computed tomography (CT) data with an emphasis on the quality of surfaces. Industrial dimensional metrology often requires high measurement accuracy and it is shown that this is retained using wavelet-based compression methods. The applied techniques include a tensor product wavelet transform and soft wavelet shrinkage. In these tests, performed on real objects, dimensional CT measurements of compressed and uncompressed volumes were compared. The necessary storage space was reduced significantly with a negligible loss of accuracy. The storage space required for a multi-sphere phantom was decreased to 4.7% (from 638 MB to 30 MB), with an average deviation below 1 μm from the original volume.

    DigitalFraunhofer AWZ CTMTMaschinenbau und Mechatronik

    Beitrag (Sammelband oder Tagungsband)

    Peter Landstorfer, Gabriel Herl, Jochen Hiller

    Investigation of Non-circular Scanning Trajectories in Robot-based Industrial X-ray Computed Tomography of Multi-material Objects

    16th International Conference on Informatics in Control, Automation and Robotics (ICINCO) [29-31 July, 2019; Prague, Czech Republic]

    2019

    DigitalFraunhofer AWZ CTMTMaschinenbau und Mechatronik

    Beitrag (Sammelband oder Tagungsband)

    Gabriel Herl, Jochen Hiller, T. Sauer

    Artifact reduction in X-ray computed tomography by multipositional data fusion using local image quality measures

    iCT 2019 9th Conference on Industrial Computed Tomography (iCT) [13-15 February, 2019; Padua, Italy]

    2019

    Abstract anzeigen

    Metal artifacts are still a major problem in X-ray industrial computed tomography. In order to reduce metal artifacts and increase the image quality of X-ray CT-scans, we suggest using projection data from multiple scans with differently positioned object orientations. We present two different approaches for multipositional CT, which are especially effective for multimaterial objects with high absorbing metal parts. On one hand, we reconstruct the different scans separatly, estimate the local quality of the resulting volumes and then fuse these volumes to an optimized volume. On the other hand, we introduce smART (shrinking merged Algebraic Reconstruction Technique) and merge sinograms of different scans, estimate the reliability of each projection pixel and then reconstruct the merged sinogram with an adapted SART reconstruction method. We demonstrate our approaches on simulations and on measurement data and are able to show a significant reduction of image artifacts qualitatively and quantitatively with the help of dimensional measurement results.

    DigitalFraunhofer AWZ CTMTMaschinenbau und Mechatronik

    Zeitschriftenartikel

    Gabriel Herl, Jochen Hiller, S. Kasperl, A. Maier

    Reduktion von Metallartefakten durch multipositionale Datenfusion in der industriellen Röntgen-Computertomographie

    tm - Technisches Messen, vol. 87, no. 2

    2019

    DOI: 10.1515/teme-2019-0137

    Abstract anzeigen

    Metallartefakte stellen eine große Herausforderung für das Messen mit Röntgen-Computertomographie dar. Dieser Beitrag stellt die Methode der multipositionalen Datenfusion zur Reduktion von Metallartefakten vor. Dazu werden mehrere Scans desselben Objekts bei unterschiedlicher Objekt-positionierung durchgeführt, aufeinander registriert und zur Fusion gemeinsam unter Betrachtung eines lokalen Gütemaßes rekonstruiert. In praxisnahen Experimenten wird der Mehrwert der Methode gezeigt. Insbesondere wird dargestellt, wie mit wenig Aufwand und ohne Vorwissen Kunststoffstrukturen trotz starker Metallartefakte sichtbar gemacht werden können, womit das Verfahren ein Alleinstellungsmerkmal gegenüber den existierenden Metallartefaktreduktionsverfahren aufweist.

    DigitalFraunhofer AWZ CTMTMaschinenbau und Mechatronik

    Beitrag (Sammelband oder Tagungsband)

    A. Stock, Gabriel Herl, T. Sauer, Jochen Hiller

    Edge preserving compression of CT scans using wavelets

    SHM-NDT 2018 International Symposium on Structural Health Monitoring and Nondestructive Testing 4-5 Oct 2018, Saarbrücken – Germany

    2018

    Abstract anzeigen

    This work addresses the subject of efficient storage of computed tomography (CT) data with an emphasis on the quality of surfaces. Industrial dimensional metrology often requires high measurement accuracy and we show that this is retained using wavelet-based compression methods. The applied techniques include a tensor product wavelet transform and soft wavelet shrinkage. In our tests on real objects, we compared dimensional CT measurements of compressed and uncompressed volumes. We were able to reduce the necessary storage space significantly with a minimal loss of accuracy. For a multi sphere phantom, we decreased the storage space to 4.7% (from 638 MB to 30 MB) with an average deviation below 1 µm from the original volume.

    DigitalFraunhofer AWZ CTMTMaschinenbau und Mechatronik

    Beitrag (Sammelband oder Tagungsband)

    A. Stock, Gabriel Herl, T. Sauer, Jochen Hiller

    Metal artifact reduction by fusion of CT scans from different positions using the unfiltered backprojection

    iCT 2018 8th Conference on Industrial Computed Tomography (iCT) 2018, 6-9 Feb, Wels, Austria

    2018

    Abstract anzeigen

    Metal objects or metal parts in an object are still a major problem of X-ray computed tomography (CT) because of so called metal artifacts. We propose a new method – a multipositional data fusion – for automatically fusing multiple CT volumes from different positions to reduce these metal artifacts. After scanning a specimen several times at different positions and reconstruction of every scan (e.g. by the filtered backprojection), we also perform an unfiltered backprojection. Based on the assumption that metal artifacts occur the most wherever X-rays are attenuated a lot, the unfiltered backprojection is used to autonomously estimate the likelihood of metal artifacts in every voxel of every scan. The different volumes are registered and then fused by weighted sum preferring the voxels with low values in the unfiltered backprojection results. In our tests on real objects, our method fully automatically created optimized volumes with significantly less metal artifacts. The multipositional data fusion was compared to the commercially multi spectra fusion of Werth Messtechnik GmbH and outperformed it in one of the use cases.

    DigitalFraunhofer AWZ CTMTMaschinenbau und Mechatronik

    Vortrag

    Gabriel Herl, Simon Rettenberger, Jochen Hiller, T. Sauer

    Metal artifact reduction by fusion of CT scans from different positions using the unfiltered backprojection

    8th Conference on Industrial Computed Tomography (iCT 2018), Wels, Österreich

    2018

    Abstract anzeigen

    Metal objects or metal parts in an object are still a major problem of X-ray computed tomography (CT) because of so called metal artifacts. We propose a new method – a multipositional data fusion – for automatically fusing multiple CT volumes from different positions to reduce these metal artifacts. After scanning a specimen several times at different positions and reconstruction of every scan (e.g. by the filtered backprojection), we also perform an unfiltered backprojection. Based on the assumption that metal artifacts occur the most wherever X-rays are attenuated a lot, the unfiltered backprojection is used to autonomously estimate the likelihood of metal artifacts in every voxel of every scan. The different volumes are registered and then fused by weighted sum preferring the voxels with low values in the unfiltered backprojection results. In our tests on real objects, our method fully automatically created optimized volumes with significantly less metal artifacts. The multipositional data fusion was compared to the commercially multi spectra fusion of Werth Messtechnik GmbH and outperformed it in one of the use cases.

    DigitalFraunhofer AWZ CTMTMaschinenbau und Mechatronik

    Vortrag

    A. Stock, Gabriel Herl, T. Sauer, Jochen Hiller

    Edge preserving compression of CT scans using wavelets

    International Symposium on Structural Health Monitoring and Nondestructive Testing, Saarbrücken

    2018

    Abstract anzeigen

    This work addresses the subject of efficient storage of computed tomography (CT) data with an emphasis on the quality of surfaces. Industrial dimensional metrology often requires high measurement accuracy and we show that this is retained using wavelet-based compression methods. The applied techniques include a tensor product wavelet transform and soft wavelet shrinkage. In our tests on real objects, we compared dimensional CT measurements of compressed and uncompressed volumes. We were able to reduce the necessary storage space significantly with a minimal loss of accuracy. For a multi sphere phantom, we decreased the storage space to 4.7% (from 638 MB to 30 MB) with an average deviation below 1 µm from the original volume.

    DigitalFraunhofer AWZ CTMTMaschinenbau und Mechatronik

    Beitrag (Sammelband oder Tagungsband)

    Gabriel Herl, Simon Rettenberger, Jochen Hiller

    Fusion mehrerer Computertomographie-Aufnahmen zur Verbesserung der Bildqualität

    Forschungsbericht 2016/2017 der Technischen Hochschule Deggendorf

    2017