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conference on Three-Dimensional Imaging, Visualization, and Display 2010 and Display Technologies and Applications for Defence, Security, and Avionics iv

作者： Yamashita, Keiji Yendo, Tomohiro Tehrani, Mehrdad Panahpour Fujii, Toshiaki Tanimoto, Masayuki Nagoya Univ Grad Sch Engn Chikusa Ku Furo Cho Nagoya Aichi 4648603 Japan Tokyo Inst Technol Grad Sch Engn Meguro Ku Tokyo 1528550 Japan

ISBN: (纸本)9780819481542

In this paper, we propose a method for high efficiency acquisition of Ray-Space for FTV (Free viewpoint TV). In this research, incomplete data is directly captured by a novel device, i.e. photodiode/lens array, and transformed to full information by Radon transform. We must capture the large amount of data in conventional acquisition of Ray-Space using multiple cameras. However Ray-space has redundancy because it consists of set of lines which depend on depth of objects. We use the Radon transform to exploit this redundancy. The Radon transform is set of projection data along different directions. Thus Ray-space can be reconstructed from projection data in limited range by the inverse Radon transform. Capturing the part of projection data correspond to capturing sums of several rays by 1 pixel. We have simulated reconstruction of Ray-space projection data which was computed by computer simulation of capturing device. As a result, by using fewer pixels than rays, we could reduce the information to reconstruct Ray-space.

关键词： FTV Ray-Space Radon transform high-efficiency acquisition projection data

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Tomographic reconstruction of Nodular images from incomplete data

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AIP conference Proceedings 2010年第1期1301卷 167-174页

作者： G. Ambartsoumian M. Xie aDepartment of Mathematics University of Texas‐Arlington Arlington TX 76019 USA bDepartment of Statistics University of Wisconsin‐Madison Madison WI 53706 USA

In many problems of medical imaging very limited amount of tomographic data can be collected. There are well developed mathematical theories proving that unless certain a priori information is known about the image, some of these limited data sets will be insufficient to generate images of acceptable quality. While in various cases such a priori information is readily available, the translation of this knowledge into mathematical constraints and their subsequent incorporation into image reconstruction algorithms has proved to be a formidable task, and there are very few results on this matter. In this paper we introduce a method that uses the knowledge of image patterns consisting of nodules to stabilize the image reconstruction in incomplete data x‐ray tomography. The technique uses a modified expectation‐maximization algorithm to cluster singularities in Radon domain, and recover the centers and radii of a finite number of nodules in the image.

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Handling of Split-and-Merge Effects and Occlusions using Feature-Based Probabilistic data Association

Handling of Split-and-Merge Effects and Occlusions using Fea...

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27th conference on Intelligent Robots and Computer Vision: Algorithms and Techniques

作者： Grinberg, Michael Ohr, Florian Fraunhofer Inst Informat & Data Proc IITB D-761313 Karlsruhe Germany

ISBN: (纸本)9780819479327

One of the big challenges in multi-target tracking is the track management and correct data association between measurements and tracks. Major reason for tracking errors are detection failures such as merged, split, incomplete or missed detections as well as clutter-based detections ( phantom objects). Those effects combined with uncertainties in existence and number of objects in the scene as well as uncertainties in their observability and dynamic object state lead to gross tracking errors. In this contribution we present an algorithm for visual detection and tracking of multiple extended targets which is capable of coping with occlusions and split and merge effects. Unlike most of the state-of-the-art approaches we utilize information about the measurements' composition gained through tracking dedicated feature points in the image and in 3D space, which allows us to reconstruct the desired object characteristics from the data even in the case of detection errors due to above-mentioned reasons. The proposed Feature-Based Probabilistic data Association approach resolves data association ambiguities in a soft threshold-free decision based not only on target state prediction but also on the existence and observability estimation modeled as two additional Markov chains. A novel measurement reconstruction scheme allows for a correct innovation in case of split, merged and incomplete measurements realizing thus a detection-by-tracking approach. This process is assisted by a grid based object representation which offers a lower abstraction level of targets extent and is used for detailed occlusion analysis.

关键词： multitarget tracking 9MTT) feature-based tracking track-before-detect detection-by-tracking probabilistic data association point tracking 6D-Vision split and merge handling occlusion handling stereo video environment perception

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Learning Manifold from incomplete image Set

Learning Manifold from Incomplete Image Set

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Chinese conference on Pattern Recognition (CCPR)

作者： Liping Gao Huiyong Pan Yubin Zhan School of Computer Zhongyuan University of Technology Zhengzhou Zhengzhou China Computer School National University of Defense Technology Changsha China

Recently, there have been several advances for developing manifold learning algorithms to learn the nonlinear manifold of collected data. To our best knowledge, however, learning manifold from incomplete data set, wherein some features of samples are missing, is still an untouched problem so far. In context of incomplete image set, an improved LTSA algorithm is proposed to learn manifold from corrupted image set. The proposed algorithm exploits an extended EM-based PCA algorithm, which can learn the principal components of incomplete image set only using the known pixels, to obtain the local tangent space coordinates instead of standard SVD technique. Experiments on benchmark data sets demonstrate the effectiveness of the proposed approach.

关键词： Pixel Manifolds image reconstruction Principal component analysis data mining Redundancy Euclidean distance

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Cross-Modality Assessment and Planning for Pulmonary Trunk Treatment Using CT and MRI Imaging

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13th International conference on Medical image Computing and Computer-Assisted Intervention (MICCAI)

作者： Vitanovski, Dime Tsymbal, Alexey Ionasec, Razvan Ioan Georgescu, Bogdan Huber, Martin Taylor, Andrew Schievano, Silvia Zhou, Shaohua Kevin Hornegger, Joachim Comaniciu, Dorin Siemens Corp Res Integrated Data Syst Princeton NJ 08540 USA Univ Erlangen Nurnberg Pattern Recognit Lab Nurnberg Germany Great Ormond St Hosp Sick Children London England

ISBN: (纸本)9783642157042

Congenital heart defect is the primary cause of death in new-borns, due to typically complex malformation of the cardiac system. The pulmonary valve and trunk are often affected and require complex clinical management and in most cases surgical or interventional treatment. While minimal invasive methods are emerging, non-invasive imaging-based assessment tools become crucial components in the clinical setting. For advanced evaluation and therapy planning purposes, cardiac Computed Tomography (CT) and cardiac Magnetic Resonance Imaging (cMRI) are important non-invasive investigation techniques with complementary properties. Although, characterized by high temporal resolution, cMRI does not cover the full motion of the pulmonary trunk. The sparse cMRI data acquired in this context include only one 3D scan of the heart in the end-diastolic phase and two 2D planes (long and short axes) over the whole cardiac cycle. In this paper we present a cross-modality framework for the evaluation of the pulmonary trunk, which combines the advantages of both, cardiac CT and cMRI. A patient-specific model is estimated from both modalities using hierarchical learning-based techniques. The pulmonary trunk model is exploited within a novel dynamic regression-based reconstruction to infer the incomplete cMRI temporal information. Extensive experiments performed on 72 cardiac CT and 74 cMRI sequences demonstrated the average speed of 110 seconds and accuracy of 1.4mm for the proposed approach. To the best of our knowledge this is the first dynamic model of the pulmonary trunk and right ventricle outflow track estimated from sparse 4D cMRI data.

关键词： Magnetic resonance imaging

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Mosaic-based 3D scene representation and rendering of circular aerial video

Mosaic-based 3D scene representation and rendering of circul...

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conference on Evolutionary and Bio-Inspired Computation - Theory and Applications iv

作者： Molina, Edgardo Zhu, Zhigang Mendoza-Schrock, Olga CUNY 138th St & Convent Ave New York NY 10031 USA CUNY Grad ctr New York NY 10016 USA Air Force Res Lab Dayton OH USA

ISBN: (纸本)9780819481689

Circular aerial video provides a persistent view over a scene and generates a large amount of imagery, much of which is redundant. The interesting features of the scene are the 3D structural data, moving objects, and scenery changes. Mosaic-based scene representations work well in detecting and modeling these features while greatly reducing the amount of storage required to store a scene. In the past, mosaic-based methods have worked well for video sequences with straight camera paths in a dominant motion direction(11). Here we expand on this method to handle circular camera motion. By using a polar transformation about the center of the scene, we are able to transform circular motion into an approximate linear motion. This allows us to employ proven 3D reconstruction and moving object detection methods that we have previously developed. Once features are found, they only need to be transformed back to the Cartesian space from the polar coordinate system.

关键词： Cameras Video 3D modeling Video surveillance Panoramic photography Oxygen 3D image processing Motion models Scene simulation Sensors

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Weighted Total Variation constrained reconstruction for reduction of metal artifact in CT

Weighted Total Variation constrained reconstruction for redu...

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IEEE Symposium on Nuclear Science (NSS/MIC)

作者： Yanbo Zhang Xuanqin Mou Hao Yan Institute of Image Processing & Pattern Recognition Xi''an Jiaotong University Xi'an Shaanxi China

TV constrained reconstruction could obtain perfect results from incomplete data, and has been applied to reduce metal artifact by assuming that the projection contaminated by metal is missing. In TV constrained reconstruction, the selection of a proper step parameter for TV minimization procedure is a key point. However, this parameter is usually selected empirically, and it is a constant for all pixels in the whole image domain, regardless of the difference of missing projection quantity at different pixels. By analyzing the relationship between the missing projections and pixels position, a Weighted Total Variation (WTV) constrained reconstruction method is proposed to reduce metal artifact in this paper. For WTV constrained method, the parameters are no longer the same, but vary over image domain as the introduced information miss rate. The simulation results show that the proposed method is more effective than current TV constraint to reduce metal artifact. Moreover, WTV constrained method is extended to other incomplete projection problems.

关键词： TV image reconstruction Metals Pixel Computed tomography X-ray imaging Noise

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Effects of thermal deformations on the sensitivity of optical systems for space application

Effects of thermal deformations on the sensitivity of optica...

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conference on Modeling, Systems Engineering and Project Management for Astronomy iv

作者： Segato, Elisa Da Deppo, Vania Debei, Stefano Cremonese, Gabriele Cherubini, Giovanni CISAS G Colombo Via Venezia 15 I-35131 Padua Italy CNR IFN UOS Luxor Padova I-35131 Padua Italy Dept Mech Engn I-35131 Padua Italy INAF Osservatorio Astron Padova I-35122 Padua Italy SELEX Galileo I-50013 Campi Bisenzio Firenze Italy

ISBN: (纸本)9780819482280

In this paper the results of the thermo-elastic analysis performed on the Stereo Imaging Channel of the imaging system SIMBIO-SYS for the BepiColombo ESA mission to Mercury is presented. The aim of the work is to determine the expected stereo reconstruction accuracy of the surface of the planet Mercury, i.e. the target of BepiColombo mission, due to the effects of the optics misalignments and deformations induced by temperature changes during the mission lifetime. The camera optics and their mountings are modeled and processed by a thermo-mechanical Finite Element Model (FEM) program, which reproduces the expected optics and structure thermo-elastic variations in the instrument foreseen operative temperature range, i.e. between -20 degrees C and 30 degrees C. The FEM outputs are elaborated using a MATLAB optimization routine: a non-linear least square algorithm is adopted to determine the surface equation (plane, spherical, n(th) polynomial) which best fits the deformed optical surfaces. The obtained surfaces are then directly imported into ZEMAX raytracing code for sequential raytrace analysis. Variations of the optical center position, boresight direction, focal length and distortion are then computed together with the corresponding image shift on the detector. The overall analysis shows the preferable use of kinematic constraints, instead of glue classical solution, for optical element mountings, this minimize the uncertainty on the Mercury Digital Terrain Model (DTM) reconstructed via a stereo-vision algorithm based on the triangulation from two optical channels.

关键词： Optical design Finite Element Analysis Uncertainty Telescope Raytrace analysis Optimization Least Square Non-linear data Fitting BepiColombo kinematic constraints

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Missing data imputation based on compressive sensing for robust speaker identification

Missing data imputation based on compressive sensing for rob...

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International conference on Wireless Communications and Signal Processing (WCSP)

作者： Xianyi Rui School of Electronic & Information Soochow University Suzhou China

In this paper, the method of missing data imputation based on the emergent field of compressive sensing for the front end of a speaker identification system in noisy conditions is investigated. Firstly, noisy speech signals are transformed into Gammatone spectrum by using cochlear filtering; then, unreliable spectral components are reconstructed given an incomplete set of reliable ones; finally, speaker features with auditory model are extracted from reconstructed Gammatone spectral data. Experimental results demonstrate that our method can improve the identification accuracy of speaker identification in noisy environments.

关键词： Speech Compressed sensing Feature extraction Noise measurement Speech recognition image reconstruction Robustness

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Trajectory matching from unsynchronized videos

Trajectory matching from unsynchronized videos

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conference on Computer Vision and Pattern Recognition (CVPR)

作者： Han Hu Jie Zhou State Key Laboratory on Intelligent Technology and Systems Tsinghua National Laboratory for Information Science and Technology TNList Department of Automation Tsinghua University Beijing China

This paper studies the problem of spatio-temporal matching between trajectories from two videos of the same scene. In real applications, trajectories are usually extracted independently in different videos. So possibly a lot of trajectories stay “alone” (have no corresponding trajectory in the other video). In this paper, we propose a novel matching algorithm which can not only find the existing correspondences between trajectories, but also recover the corresponding trajectories of “alone” ones. First, we cast trajectory matching problem as an element recovering problem from a matrix constructed by matched trajectories of the two videos, which is naturally incomplete. Then, under affine camera assumption, we recover the matrix by sparse representation and ℓ 1 regularization techniques. Finally, the results are refined to the case of perspective projection by a local depths estimation procedure. Our algorithm can handle noisy, incomplete or outlying data. Experiments on both synthetic data and real videos show that the proposed method has good performance.

关键词： Layout Cameras Video sequences Subspace constraints Laboratories Sparse matrices Computer vision Feature extraction image reconstruction Intelligent systems

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