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IEEE/RSJ International conference on Intelligent Robots and Systems

作者： Jose Iglesias Pedro Mirado Rodrigo ventura "Instituto de Sistemas e Robotica" "Instituto Superior Tecnico Universidade de Lisboa" Portugal

ISBN: (纸本)9781509037636

In this paper we address the 3D reconstruction of points, on a non-central catadioptric system, composed by a mirror, a projector, and a perspective camera. The goal of the paper is to propose a framework to build an omnidirectional depth camera, towards an omnidirectional RGB-D camera system. The main contributions are: an efficient technique to project 3D points from the world to an image of a general non-central catadioptric camera;the definition of the template pattern (for both the projector and camera's images);and the matching between the projection of these features to the world and its respective images. The 3D depth is directly recovered using the template matching approach. In conclusion, we apply some filtering techniques to improve the results. To evaluate the proposed framework, we test the method using synthetic data, under different levels and types of noises, proving that the framework is robust to noise and, thus, can be put into practice.

关键词： Cameras Mirrors Three-dimensional displays image reconstruction Robot vision systems Light sources three-dimensional displays Cameras robot vision system Mirrors LIGHT SOURCES image reconstruction catadioptric Noise Frameworks noncentral

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3-D UNDERSTANDING OF ELECTRON MICROSCOPY imageS OF NANO BIO OBJECTS BY COMPUTING GENERATIvE MECHANICAL MODELS

3-D UNDERSTANDING OF ELECTRON MICROSCOPY IMAGES OF NANO BIO ...

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IEEE International conference on image Processing

作者： Yunye Gong Peter C. Doerschuk Cornell University Electrical and Computer Engineering

ISBN: (纸本)9781467399623

Cryo electron microscopy records essentially projection images of each of many instances of a nano bio object. This data allows reconstruction of a stochastic model of the object, i.e., the mean and covariance functions of the electron scattering intensity of the object. Understanding the covariance function, which characterizes the heterogeneity of the instances of the object, is challenging because the covariance function is not wide-sense stationary but instead depends separately on the two three-dimensional positions. This paper describes a method, qualitatively motivated by fluctuation-dissipation theory, for estimating a spring-and-mass mechanical model of the object. Then, from the model, a wide range of properties of the object can be understood, such as normal modes of vibration.

关键词： image understanding Computational imaging Electron microscopy Tomography

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Increasing Spatial Resolution through Automated Catheter Rotation in High Definition Urethral Pressure Profilometry

Increasing Spatial Resolution through Automated Catheter Rot...

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IEEE International conference on Automation Science and Engineering

作者： Mario Klunder Oliver Sawodny Ronny Feuer University of Stuttgart Institute for System Dynamics 70550 Germany

ISBN: (纸本)9781509024100

Urethral pressure profilometry (UPP) is a tool in the diagnosis of stress urinary incontinence. The pressure profile on the urethra's inside is measured by a catheter with pressure sensing capability to assess the contraction strength of the sphincter muscle. In order to improve this diagnostic method, high definition urethral pressure profilometry (HD-UPP) combining enhanced UPP hardware and signal processing algorithms has been developed. from HD-UPP data, a high resolution pressure image is reconstructed on the urethra's inside. In this contribution, we investigate how the spatial resolution can be increased through automated catheter rotation during retraction. As catheter rotation has an adverse effect on the amplification of measurement errors in signal reconstruction, we additionally present a method to optimize sensor positions on the catheter for optimal reconstruction stability in presence of catheter rotation. Finally, it is shown that through automated catheter rotation the same resolution as with an additional pressure sensor and non-rotating catheter retraction can be achieved at no extra cost.

关键词： Catheters Bandwidth Pressure sensors Spatial resolution Signal reconstruction Trajectory image reconstruction

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A fast gradient projection method for 3D image reconstruction from limited tomographic data

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Journal of Physics: conference Series 2017年第1期904卷

作者： v.L. Coli E. Loli Piccolomini E. Morotti L. Zanni Department of Physics Informatics and Mathematics University of Modena and Reggio Emilia Department of Mathematics University of Bologna Department of Mathematics University of Padova

We consider in this paper the problem of reconstructing 3D Computed Tomography images from limited data. The problem is modeled as a nonnegatively constrained minimization problem of very large size. In order to obtain an acceptable image in short time, we propose a scaled gradient projection method, accelerated by exploiting a suitable scaling matrix and efficient rules for the choice of the step-length. In particular, we select the step-length either by alternating Barzilai-Borwein rules or by exploiting a limited number of back gradients for approximating second-order information. Numerical results on a 3D Shepp-Logan phantom are presented and discussed.

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Portability of Tv-Regularized reconstruction Parameters to varying data Sets

Portability of TV-Regularized Reconstruction Parameters to V...

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conference on image Processing for Medicine (BvM)

作者： Amrehn, Mario Maier, Andreas Dennerlein, Frank Hornegger, Joachim FAU Erlangen Nurnberg Pattern Recognit Lab Erlangen Germany Erlangen Grad Sch Adv Opt Technol SAOT Erlangen Germany

ISBN: (纸本)9783662462249;9783662462232

In C-arm computed tomography there are certain constraints due to the data acquisition process which can cause limited raw data. The reconstructed image's quality may significantly decrease depending on these constraints. To compensate for severely under-sampled projection data during reconstruction, special algorithms have to be utilized, more robust to such ill-posed problems. In the past few years it has been shown that reconstruction algorithms based on the theory of compressed sensing are able to handle incomplete data sets quite well. In this paper, the iterative iTv reconstruction method by Ludwig Ritschl et al. is analyzed regarding it's elimination capabilities of image artifacts caused by incomplete raw data with respect to the settings of it's various parameters. The evaluation of iTv and the data dependency of iterative reconstruction's parameters is conducted in two stages. First, projection data with severe angular under-sampling is acquired using an analytical phantom. Proper reconstruction parameters are selected by analyzing the reconstruction results from a set of proposed parameters. In a second step multiple phantom data sets are acquired with limited angle geometry and a small number of projections. The iTv reconstructions of these data sets are compared to short-scan FDK and SART reconstruction results, highlighting the distinct data dependence of the iTv reconstruction parameters.

关键词： Phantoms

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BOOSTING PERFORMANCE AND SPEED OF SINGLE-image SUPER-RESOLUTION BASED ON PARTITIONED LINEAR REGRESSION

BOOSTING PERFORMANCE AND SPEED OF SINGLE-IMAGE SUPER-RESOLUT...

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IEEE International conference on image Processing

作者： Anustup Choudhury Peter van Beek Dolby Laboratories Sharp Laboratories of America

ISBN: (纸本)9781467399623

In this paper, we show how to boost the performance and speed of the Simple Functions (SF) algorithm for single-image super-resolution [1]. This method partitions the low-resolution patch space and learns linear regressors to map low-resolution to high-resolution patches. We optimize the partitioning of the patch feature space by first employing dimensionality reduction and then explicitly minimizing the overall super-resolution reconstruction error during training. We also improve selection of training patches. In the super-resolution stage, we use a k-d tree for fast nearest neighbor search of partitions, and combine multiple regression models from neighboring partitions. Experimental results on benchmark data sets show improvements in both image quality and speed over SF. Also, our method outperforms state-of-the-art super-resolution methods in image quality.

关键词： Super-resolution Approximate nearest neighbor search Patch-based Up-scaling Regression super-resolution Nearest neighbor query Regression (Psychology) partitions speed image quality

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Advanced Techniques for reconstruction of incomplete Network data 1

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7th International ICST conference on Digital Forensics and Cyber Crime (ICDF2C)

作者： Matousek, Petr Pluskal, Jan Rysavy, Ondrej vesely, vladimir Kmet, Martin Karpisek, Filip vymlatil, Martin Brno Univ Technol Bozetechova 2 CS-61090 Brno Czech Republic

ISBN: (数字)9783319255125

ISBN: (纸本)9783319255125;9783319255118

Network forensics is a method of obtaining and analyzing digital evidences from network sources. Network forensics includes data acquisition, selection, processing, analysis and presentation to investigators. Due to high volumes of transmitted data the acquired information can be incomplete, corrupted, or disordered which makes further reconstruction difficult. In this paper, we address the issue of advanced parsing and reconstruction of incomplete, corrupted, or disordered data packets. We introduce a technique that recovers TCP or UDP conversations so they could be further analyzed by application parsers. Presented technique is implemented in a new network forensic tool called Netfox Detective. We also discuss current challenges in parsing web mail communication, SSL decryption and Bitcoins detection.

关键词： Network forensic tools TCP reassembling Traffic reconstruction Web mail Bitcoin SSL encryption

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PERSISTENT HOMOLOGY OF ATTRACTORS FOR ACTION RECOGNITION

PERSISTENT HOMOLOGY OF ATTRACTORS FOR ACTION RECOGNITION

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IEEE International conference on image Processing

作者： vinay venkataraman Karthikeyan Natesan Ramamurthy Pavan Turaga School of Arts Media and Engineering Arizona State University Tempe AZ Mathematical Sciences Department IBM Thomas J. Watson Research Center Yorktown Heights NY

ISBN: (纸本)9781467399623

In this paper, we propose a novel framework for dynamical analysis of human actions from 3D motion capture data using topological data analysis. We model human actions using the topological features of the attractor of the dynamical system. We reconstruct the phase-space of time series corresponding to actions using time-delay embedding, and compute the persistent homology of the phase-space reconstruction. In order to better represent the topological properties of the phase-space, we incorporate the temporal adjacency information when computing the homology groups. The persistence of these homology groups encoded using persistence diagrams are used as features for the actions. Our experiments with action recognition using these features demonstrate that the proposed approach outperforms other baseline methods.

关键词： Three-dimensional displays Hidden Markov models Time series analysis data analysis Feature extraction data models Analytical models three-dimensional displays data models Hidden Markov models ANALYSIS MODELS time series analysis Feature extraction data analysis Attractor homology Homology Phase space Action topological features

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image reconstruction in serial femtosecond nanocrystallography using x-ray free-electron lasers 8

Image reconstruction in serial femtosecond nanocrystallograp...

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conference on image reconstruction from incomplete data vIII

作者： Chen, Joe P. J. Kirian, Richard A. Beyerlein, Kenneth R. Bean, Richard J. Morgan, Andrew J. Yefanov, Oleksandr M. Arnal, Romain D. Wojtas, David H. Bones, Phil J. Chapman, Henry N. Spence, John C. H. Millane, Rick P. Univ Canterbury Dept Elect & Comp Engn Computat Imaging Grp Christchurch 1 New Zealand Arizona State Univ Dept Phys Tempe AZ 85287 USA DESY Ctr Free Electron Laser Sci D-22607 Hamburg Germany European XFEL GmbH D-22761 Hamburg Germany Univ Hamburg D-22761 Hamburg Germany

ISBN: (纸本)9781628417661

Serial femtosecond nanocrystallography (SFX) is a form of x-ray coherent diffraction imaging that utilises a stream of tiny nanocrystals of the biological assembly under study, in contrast to the larger crystals used in conventional x-ray crystallography using conventional x-ray synchrotron x-ray sources. Nanocrystallography utilises the extremely brief and intense x-ray pulses that are obtained from an x-ray free-electron laser (XFEL). A key advantage is that some biological macromolecules, such as membrane proteins for example, do not easily form large crystals, but spontaneously form nanocrystals. There is therefore an opportunity for structure determination for biological molecules that are inaccessible using conventional x-ray crystallography. Nanocrystallography introduces a number of interesting image reconstruction problems. Weak diffraction patterns are recorded from hundreds of thousands of nancocrystals in unknown orientations, and these data have to be assembled and merged into a 3D intensity dataset. The diffracted intensities can also be affected by the surface structure of the crystals that can contain incomplete unit cells. Furthermore, the small crystal size means that there is potentially access to diffraction information between the crystalline Bragg peaks. With this information, phase retrieval is possible without resorting to the collection of additional experimental data as is necessary in conventional protein crystallography. We report recent work on the diffraction characteristics of nanocrystals and the resulting reconstruction algorithms.

关键词： x-ray crystallography x-ray free-electron laser nanocrystal serial femtosecond nanocrystallography phase retrieval

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First Results from a High-Resolution Small Animal SiPM PET Insert for PET/MR Imaging at 7T

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IEEE TRANSACTIONS ON NUCLEAR SCIENCE 2016年第5期63卷 2424-2433页

作者： Goertzen, Andrew L. Stortz, Greg Thiessen, Jonathan D. Bishop, Daryl Khan, Muhammad Salman Kozlowski, Piotr Retiere, Fabrice Schellenberg, Graham Shams, Ehsan Sossi, vesna Thompson, Christopher J. Univ Manitoba Dept Radiol Winnipeg MB R3E 3P4 Canada Univ Manitoba Dept Phys & Astron Winnipeg MB R3E 3P4 Canada Hlth Sci Ctr Sect Nucl Med PET CT Imaging Program Winnipeg MB R3E 3P4 Canada Univ British Columbia Dept Phys & Astron Vancouver BC V5T 2E4 Canada Western Univ Imaging Program Lawson Hlth Res Inst London ON N6A 3K7 Canada Western Univ Dept Med Biophys London ON N6A 3K7 Canada TRIUMF Detector Dev Grp Vancouver BC V6T 2A3 Canada Univ Manitoba Dept Elect & Comp Engn Winnipeg MB R3E 3P4 Canada Univ British Columbia Dept Radiol Vancouver BC R3T 2N2 Canada Univ Manitoba Biomed Engn Grad Program Winnipeg MB R3E 3P4 Canada Winnipeg Reg Hlth Author Winnipeg MB R3B 1E2 Canada McGill Univ Montreal Neurol Inst Montreal PQ H3A 0G4 Canada

We present the initial results from a small animal PET insert designed to be operated inside a 7T MRI. The insert fits within the 114 mm inner diameter of the Bruker BGA-12S gradient coil while accommodating the Bruker 35 mm volume RF coil (outer diameter 60 mm), both used in the Bruker 70/20 MRI systems. The PET insert is a ring comprising 16 detectors. Each detector has a dual-layer offset (DLO) lutetium-yttrium oxyorthsilicate (LYSO) scintillator array read out by two SensL SPMArray4B SiPM arrays. The DLO scintillator has bottom (top) layers of: 22 x 10 (21 x 9) crystals of size 1.2 x 1.2 x6 (4) mm(3) for a total of 409 crystals per block, providing an axial extent of 28.17 mm. The detector outputs are multiplexed to four signals using a custom readout board and digitized using the OpenPET data acquisition platform. The detector flood images successfully resolve over 99% of the crystals, with average energy resolution of 12.5 +/- 2.0% at 511 kev. Testing of the PET system inside the MRI showed that the PET insert had no effect on MRI image homogeneity and only a small effect on echo planar images (EPI) signal to noise ratio (SNR) (-9%), with neither PET nor MRI images showing obvious artefacts. These acquisitions used the OpenPET operating in "oscilloscope mode" with USB2.0 interface, allowing a maximum total singles event rate of 280 kcps, strongly limiting the count rate capabilities of the system. The PET radial spatial resolution (as measured with a Na-22 point source and FBP-3DRP reconstruction) is 1.17 mm at the centre, degrading to 1.86 mm at a 15 mm radial offset. Simultaneous phantom and mouse PET/MR imaging produced good quality images that were free of any obvious artefacts.

关键词： Dual-layer offset scintillator PET insert PET/MRI silicon photomultiplier small animal PET

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