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IEEE conference on Computer vision and Pattern Recognition

作者： Lili Tao Bogdan J. Matuszewski Applied Digital Signal and Image Processing Research Centre University of Central Lancashire

ISBN: (纸本)9781467364102

In this paper, a novel approach based on a non-linear manifold learning technique is proposed to recover 3D non-rigid structures from 2D image sequences captured by a single camera. Most of the existing approaches assume that 3D shapes can be accurately modelled in a linear subspace. These techniques perform well when the deformations are relatively small or simple, but fail when more complex deformations need to be recovered. The non-linear deformations are often observed in highly flexible objects for which the use of the linear model is impractical. A specific type of shape variations might be governed by only a small number of parameters, therefore can be well-represented in a low dimensional manifold. We learn a nonlinear shape prior using diffusion maps method. The key contribution in this paper is the introduction of the shape prior that constrain the reconstructed shapes to lie in the learned manifold. The proposed methodology has been validated quantitatively and qualitatively on 2D points sequences projected from the 3D motion capture data and real 2D video sequences. The comparisons of the proposed manifold based method against several state-of-the-art techniques are shown on different types of deformable objects.

关键词： Shape Manifolds Three-dimensional displays Trajectory Training Cameras image reconstruction

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A multi-FPGA implementation of real-time reconstruction using Total Focusing Method

A multi-FPGA implementation of real-time reconstruction usin...

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IEEE International conference on Cyber Technology in Automation, Control, and Intelligent Systems

作者： Mickael Njiki Samir Bouaziz Abdelhafid Elouardi Olivier Casula Olivier Roy UMR Université Paris-Sud Orsay France CEA LIST M2M-NDT Gif-sur-Yvette France CEA LIST M2M-NDT France

Total Focusing Method (TFM) ultrasound imaging has many advantages in terms of flexibility and accuracy in comparison with traditional imaging techniques. However, one major drawback is the high number of data acquisition and computing requirements for this imaging technique. Due to those constraints, the TFM algorithm was earlier classified in the field of post-processing tasks. Real-time imaging is a key aspect in Non Destructive Evaluation (NDE) using ultrasound techniques. In this context, fast and precise control evaluation should be implemented on a variety of pieces. This paper describes a dedicated architecture for real-time TFM imaging using the Full Matrix Capture (FMC). In the acquisition process, data are sequentially acquired from phased arrays and temporally stored in order to be processed with synthetic focusing techniques such as the TFM algorithm. The FMC-TFM architecture consists of a set of interconnected functional blocs and integrated in an embedded system. Initially, this acoustic measurement system was dedicated to the parallel data acquisition from phased arrays. The architecture was entirely described using vHDL language, synthesized and implemented on a v5FX70T Xilinx FPGA for the control part and a v5SX95T Xilinx FPGA for the acquisition part. The maximum operating frequency is 147.3 MHz for the control part and 161.3 MHz for the acquisition part. The architecture is able to perform real-time FMC-TFM imaging at a maximum frame rate of 73 frames/s and a maximum resolution of 128×128 pixels, which is sufficient as a performance for a real-time imaging with a good characterization of defects.

关键词： image reconstruction Focusing Real-time systems Field programmable gate arrays Generators Acoustics

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Computational assessment of the fractional flow reserve from intravascular ultrasound and coronary angiography data: A pilot study

Computational assessment of the fractional flow reserve from...

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Annual International conference of the IEEE Engineering in Medicine and Biology Society (EMBC)

作者： Panagiotis K. Siogkas Michail I. Papafaklis Antonis I. Sakellarios Kostas A. Stefanou Christos v. Bourantas Lambros M. Athanasiou Christos v. Bellos Themis P. Exarchos Katerina K. Naka Lampros K. Michalis Oberdan Parodi Dimitrios I. Fotiadis Unit of Medical Technology and Intelligent Information Systems University of Ioannina GR Cardiovascular Division Harvard Medical School Boston MA USA Biomedical Research Institute – FORTH Ioannina Greece Dept. of Cardiology in Medical School University of Ioannina Ioannina Greece Consiglio Nazionale delle Ricerche (IFC CNR) Instituto di Fisiologia Clinica Pisa Italy

Cardiovascular disease is one of the primary causes of morbidity and mortality around the globe. Thus, the diagnosis of critical lesions in coronary arteries is of utmost importance in clinical practice. One useful and efficient method to assess the functional severity of one or multiple lesions in a coronary artery is the calculation of the fractional flow reserve (FFR). In the current work, we present a method which allows the calculation of the FFR value computationally, without the use of a pressure wire and the induction of hyperemia, using intravascular ultrasound (IvUS) and biplane angiography images for three-dimensional (3D) coronary artery reconstruction and measurements of the volumetric flow rate derived from angiographic sequences. The simulated FFR values were compared to the invasively measured FFR values in 7 cases, presenting high correlation (r=0.85) and good agreement (mean difference=0.002). FFR assessment without employing a pressure wire and the induction of hyperemia is feasible using 3D reconstructed coronary artery models from angiographic and IvUS data coupled with computational fluid dynamics.

关键词： Arteries Three-dimensional displays Wires Solid modeling Blood flow image reconstruction Angiography

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3D trajectories re-construction of droplets ejected in controlled tungsten melting studies in ASDEX Upgrade

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JOURNAL OF NUCLEAR MATERIALS 2013年第sup期438卷 S846-S851页

作者： Yang, Zhongshi Krieger, K. Lunt, T. Brochard, F. Briancon, J. -L. Neu, R. Dux, R. Janzer, A. Potzel, S. Puetterich, T. Max Planck Inst Plasma Phys EURATOM Assoziat D-85748 Garching Germany Chinese Acad Sci Inst Plasma Phys Hefei 230031 Peoples R China Univ Lorraine Inst Jean Lamour F-54506 Vandoeuvre Les Nancy France

Two fast visible range camera systems with vertically and tangentially oriented crossed viewing fields in the divertor region of ASDEX Upgrade were used to observe tungsten (W) droplets ejected from a melting W-pin into the divertor plasma. To obtain the spatial (3D) trajectories of the tungsten droplets, the trajectory of a given droplet in the (2D) camera image coordinate system was derived for each view separately. from these data, the 3D droplet position was derived by computing the shortest line segment connecting crossed viewing chords to a given droplet taking the centre coordinate of the line segment as actual coordinate. The experimental error of the derived position was estimated from the length of the connecting line segment. In the toroidal direction, the computed trajectories can be described by an analytical transport model for the droplets assuming an initial droplet diameter in the range of 60100 mu m. In the vertical direction the vertical distance droplets travelled when reaching the edge of the viewing field also agrees with the model predictions. However, discrepancies are found with respect to the time point whence a droplet reverts its initial downwards motion due to centrifugal forces exceeding gravity and plasma generated force components. (C) 2013 Elsevier B. v. All rights reserved.

关键词： TRAJECTORIES (Mechanics) MELTING points image reconstruction THREE-dimensional imaging image processing NUCLEAR physics experiments

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Support estimation for phase retrieval image reconstruction from sparse-aperture interferometry data

Support estimation for phase retrieval image reconstruction ...

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conference on image reconstruction from incomplete data vII

作者： DeSantis, Zachary J. Fienup, James R. Univ Rochester Inst Opt Rochester NY 14627 USA

ISBN: (纸本)9780819492173

Imaging interferometry suffers from sparse Fourier measurements, and, at the visible wavelengths, a lack of phase information, creating a need for an image reconstruction algorithm. A support constraint is useful for optimization but is often not known a priori. The two-point rule for finding an object support from the autocorrelation is limited in usefulness by the sparsity and non-uniformity of the Fourier data and is insufficient for image reconstruction. Compactness, a common prior, does not require knowledge of the support. Compactness penalizes solutions that have bright pixels away from the center, favoring soft-edged objects with a bright center and darker extremities. With regards to imaging hard-edged objects such as satellites, a support constraint is desired but unknown and compactness may be unfavorable. Combining various techniques, a method of simultaneously estimating the object's support and the object's intensity distribution is presented. Though all the optimization parameters are in the image domain, we are effectively performing phase retrieval at the measurement locations and interpolation between the sparse data points.

关键词： image reconstruction imaging interferometry interpolation phase retrieval support constraint

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Human motion capture using 3D reconstruction based on multiple depth data

Human motion capture using 3D reconstruction based on multip...

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IEEE International conference on Systems, Man, and Cybernetics

作者： Wassim Filali Jean-Thomas Masse Frédéric Lerasle Jean-Louis Boizard Michel Devy CNRS Laboratoire d'Analyse et d'Architecture des Systèmes 7 avenue du colonel Roche F-31400 Toulouse France Université de Toulouse UPS LAAS F-31400 Toulouse France.

ISBN: (纸本)9781479906505

Human motion is a critical aspect of interacting, even between people. It has become an interesting field to exploit in human-robot interaction. Even with today's computing power, it remains a difficult task to successfully follow the human's motion from image processing alone. New sensors were introduced, bringing depth sensing at low or no cost. Using this new technology, this paper presents a new methodology to see space with multiple depth sensors, using machine-learning technique, and features in voxel space to learn to reconstruct humans' joints in single, fused acquisitions. We back up and validate the procedure with ground truth acquired from commercial Motion Capture, and prove the approach to perform particularly well on an expansive set of motion and poses, and compare with current standard software on single depth sensors.

关键词： human posture reconstruction depth sensing sensor fusion machine learning voxel pixel Sensor fusion Human motion motion capture Machine Learning three-dimensional displays Artificial Intelligence ground truth Sensors

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Imaging from scattered fields: limited data and degrees of freedom

Imaging from scattered fields: limited data and degrees of f...

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conference on image reconstruction from incomplete data vII

作者： Ritter, R. Shane Fiddy, Michael A. Perigon Int Inc 931 Ind Dr Matthews NC 28105 USA Univ N Carolina Ctr Optoelect & Opt Commun Charlotte NC 28223 USA

ISBN: (纸本)9780819492173

We describe how the number of degrees of freedom associated with a scattering experiment provides a guide to the minimum number of source and receiver locations required to image the scattering target. Since the number of degrees of freedom is approximately fixed, additional measurements do not necessarily improve the image fidelity in the absence of any prior knowledge. We illustrate these observations using a fast nonlinear inverse scattering method.

关键词： Imaging inverse scattering degrees of freedom

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MR images from fewer data

MR images from fewer data

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conference on image reconstruction from incomplete data vII

作者： vafadar, Bahareh Bones, Philip J. Univ Canterbury Dept Elect & Comp Engn Computat Imaging Grp Christchurch 1 New Zealand

ISBN: (纸本)9780819492173

There is a strong motivation to reduce the amount of acquired data necessary to reconstruct clinically useful MR images, since less data means faster acquisition sequences, less time for the patient to remain motionless in the scanner and better time resolution for observing temporal changes within the body. We recently introduced an improvement in image quality for reconstructing parallel MR images by incorporating a data ordering step with compressed sensing (CS) in an algorithm named 'PECS'.(1) That method requires a prior estimate of the image to be available. We are extending the algorithm to explore ways of utilizing the data ordering step without requiring a prior estimate. The method presented here first reconstructs an initial image x(1) by compressed sensing (with scarcity enhanced by SvD), then derives a data ordering from x(1), R'(1), which ranks the voxels of x(1) according to their value. A second reconstruction is then performed which incorporates minimization of the first norm of the estimate after ordering by R'(1), resulting in a new reconstruction x(2). Preliminary results are encouraging.

关键词： Parallel Magnetic Resonance Imaging (pMRI) Compressed Sensing (CS)

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Hidden Markov Models with Graph Densities for Action Recognition

Hidden Markov Models with Graph Densities for Action Recogni...

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International Joint conference on Neural Networks

作者： Michael Glodek Edmondo Trentin Friedhelm Schwenker Günther Palm Institute of Neural Information Processing University of Ulm Germany Dipartimento di Ingegneria dell' Infor mazione (DII) University of Siena Italy

ISBN: (纸本)9781467361279

Human action recognition in video streams is a fast developing field in pattern recognition and machine learning. Local image representations, e.g. space-time interest points [1], have proven to be the current most reliable choice of feature in sequences in which the region of interest is difficult to determine [2]. However, the question how to deal with more severe occlusions has large been ignored [2]. This work proposes a new approach which directly addresses heavy occlusions by modeling the skeleton-based features using a probability density functions (PDF) defined over graphs. We integrated the proposed density into an hidden Markov model (HMM) to model sequences of graphs of arbitrary sizes, i.e. occlusions setting may change over time. The approach is evaluated using a dataset embracing three action classes, studying six different types of occlusions (involving the removal of subgraphs from the graphical representation of action sequence). The presented study shows clearly that actions from even heavily occluded sequences can be reliably recognized.

关键词： Action recognition incomplete data

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Superresolved image reconstruction from incomplete data

Superresolved Image Reconstruction from Incomplete Data

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conference on image reconstruction from incomplete data vII

作者： Chuang, Yi-Chen Dudley, Richard Fiddy, Michael A. Nanyang Technol Univ Sch Elect & Elect Engn 50 Nanyang Ave Singapore 639798 Singapore Univ N Carolina Dept Phys & Opt Sci Charlotte NC 28223 USA Univ N Carolina Ctr Optoelect & Opt Commun Charlotte NC 28223 USA

ISBN: (纸本)9780819492173

A finite thickness slab of a metamaterial having a refractive index close to n = -1, can be used for sub-wavelength scale imaging. In the image domain, the measured fields contain evanescent wave contributions from subwavelength scale features in the object but these have to be related to the intrinsic parameters describing the scatterer such as refractive index or permittivity. For weak scatterers there can be a simple relationship between the field distribution and the permittivity profile. However for strong (multiple) scatterers and, more importantly, for objects for which subwavelength features contribute to the scattered (near) field, there is no simple relationship between the measured data and the permittivity profile. This is a significant inverse scattering problem for which no immediate solution exists and given the metamaterial slab's limitations one cannot assume that either angle or wavelength diversity will be available to apply an inverse scattering algorithm. We consider wavelength diversity in this paper to acquire the measured data necessary to estimate a superresolved solution to the inverse scattering problem.

关键词： Metamaterials superresolution scattering inverse scattering algorithm

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