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IEEE Conference on computer Vision and Pattern Recognition

作者： Menglong Yang Yiguang Liu Longyin Wen Zhisheng You Stan Z. Li Key Laboratory of Fundamental Synthetic Vision Graphics and Image for National Defense School of Aeronautics and Astronautics & Computer Science Sichuan University Center for Biometrics and Security Research & National Laboratory of Pattern Recognition Institute of Automation Chinese Academy of Sciences

ISBN: (纸本)9781479951192

Mutual occlusions among targets can cause track loss or target position deviation, because the observation likelihood of an occluded target may vanish even when we have the estimated location of the target. This paper presents a novel probability framework for multitarget tracking with mutual occlusions. The primary contribution of this work is the introduction of a vectorial occlusion variable as part of the solution. The occlusion variable describes occlusion states of the targets. This forms the basis of the proposed probability framework, with the following further contributions: 1) Likelihood: A new observation likelihood model is presented, in which the likelihood of an occluded target is computed by referring to both of the occluded and occluding targets. 2) Priori: Markov random field (MRF) is used to model the occlusion priori such that less likely "circular" or "cascading" types of occlusions have lower priori probabilities. Both the occlusion priori and the motion priori take into consideration the state of occlusion. 3) Optimization: A realtime RJMCMC-based algorithm with a new move type called "occlusion state update" ispresented. Experimental results show that the proposed framework can handle occlusions well, even including long-duration full occlusions, which may cause tracking failures in the traditional methods.

关键词： Target tracking Probabilistic logic Approximation algorithms Cameras Proposals Computational modeling

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Head motion compensation for arterial spin labeling using optical motion tracking

Head motion compensation for arterial spin labeling using op...

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International Workshop on Clinical image-Based Procedures: From Planning to Intervention, CLIP 2012 - Held in Conjunction with MICCAI 2012

作者： Hoßbach, Martin Gregori, Johannes Wesarg, Stefan Günther, Matthias Fraunhofer Institute for Computer Graphics Research IGD Darmstadt Germany Fraunhofer Institute for Medical Image Computing MEVIS Bremen Germany

ISBN: (纸本)9783642380785

Monitoring of Brain perfusion using Arterial Spin Labeling (ASL) during thrombolysis is an example of an MR procedure that will take over one hour. During this time, patient head motion is inevitable. Among the solutions to this problem is motion tracking, which is used to provide the patient's head motion to the MRI scanner to compensate for this motion. We present an approach for head motion tracking which is designed to fit into clinical workflow: Blue paper dots are attached to the patient's forehead and tracked using a stereo camera setup which is mounted to the MRI head coil and easily removed and replaced. The core algorithms are explained and evaluated. Results from clinical experiments conclude the evaluation. © Springer-Verlag 2013.

关键词： Scanning

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Isoptics of Bézier curves

Isoptics of Bézier curves

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作者： Kunkli, Roland Papp, Ildikó Hoffmann, Miklós Dept. of Computer Graphics and Image Processing University of Debrecen H-4010 Debrecen Hungary Institute of Mathematics and Computer Science Károly Eszterházy University H-3300 Eger Hungary

Given a planar curve s(t), the locus of those points from which the curve can be seen under a fixed angle is called isoptic curve of s(t). Isoptics are well-known and widely studied, especially for some classical curves such as e.g. conics (Loria, 1911). They can theoretically be computed for a large class of parametric curves by the help of their support functions or by direct computation based on the definition, but unfortunately these computations are extremely complicated even for simple curves. Our purpose is to describe the isoptics of those curves which are still frequently used in geometric modeling - the Bézier curves. It turns out that for low degree Bézier curves the direct computation is possible, but already for degree 4 or 5 the formulas are getting too complicated even for computer algebra systems. Thus we provide a new way to solve the problem, proving some geometric relations of the curve and their isoptics, and computing the isoptics as the envelope of envelopes of families of isoptic circles over the chords of the curve. © 2012 Elsevier B.V.

关键词： Algebra

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Technical foundation and calibration methods for time-of-flight cameras

Technical foundation and calibration methods for time-of-fli...

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Dagstuhl 2012 Seminar on Time-of-Flight Imaging: Sensors, Algorithms, and Applications and Workshop on Imaging New Modalities, Held at the German Conference on Pattern Recognition, GCPR2013

作者： Lefloch, Damien Nair, Rahul Lenzen, Frank Schäfer, Henrik Streeter, Lee Cree, Michael J. Koch, Reinhard Kolb, Andreas Computer Graphics Group University of Siegen Germany Heidelberg Collaboratory for Image Processing University of Heidelberg Germany Intel Visual Computing Institute Saarland University Germany University of Waikato New Zealand Multimedia Information Processing University of Kiel Germany

ISBN: (纸本)9783642449635

Current Time-of-Flight approaches mainly incorporate an continuous wave intensity modulation approach. The phase reconstruction is performed using multiple phase images with different phase shifts which is equivalent to sampling the inherent correlation function at different locations. This active imaging approach delivers a very specific set of influences, on the signal processing side as well as on the optical side, which all have an effect on the resulting depth quality. Applying ToF information in real application therefore requires to tackle these effects in terms of specific calibration approaches. This survey gives an overview over the current state of the art in ToF sensor calibration. © Springer-Verlag 2013.

关键词： Calibration

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Human object extraction using nonextensive fuzzy entropy and chaos differential evolution

International Journal of Signal Processing, Image Processing...

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International Journal of Signal processing, image processing and Pattern Recognition 2013年第2期6卷 43-54页

作者： Nie, Fangyan Li, Jianqi Rong, Qiusheng Pan, Meisen Zhang, Fen Institute of Graphics and Image Processing Technology College of Computer Science and Technology Hunan University of Arts and Science China

Human object extraction from infrared image has broad applications, and has become an active research area in image processing community. Combined with chaos differential evolution (CDE) algorithm and morphological operators, a novel infrared human target extraction method is proposed based on nonextensive fuzzy entropy. Firstly, the image was transformed into a fuzzy domain by fuzzy membership function, and the image nonextensive fuzzy entropy was constructed. Then, the image was segmented by thresholding based on the maximum entropy principle and the pseudoadditivity rule of nonextensive entropy. In order to reduce the search time of optimal threshold selection, the CDE algorithm was presented. Finally, the object was extracted using morphological operators to denoise, fill cavity on the threshold segmented image. Experimental results show that the proposed method is efficient and requires less computation time.

关键词： Evolutionary algorithms

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Text line detection based on mutation analysis

Text line detection based on mutation analysis

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2013 5th International Conference on Computational and Information Sciences, ICCIS 2013

作者： Hou, Dewen Wang, Xichang Liu, Jiang Chen, Xia Key Laboratory for Distributed Computer Software School of Information and Science Engineering Shandong Normal University Shandong China Shandong Oumasoft Co. Ltd Research Institute of Digital Image Processing Shandong China

ISBN: (纸本)9780769550046

A text line detection method based on wavelet transformation and mutation analysis is proposed in this paper. First the character density image is acquired from the input document image by the project function with strips, and then the density image is analyzed by wavelet transformation where the Gaussian or its derivative function is used as the wavelet basis. The local peak positions indicate the line texture which will be continuous and single pixel. Because of the statistical properties of project function and wavelet transformation of mutations signal detection, this algorithm is not sensitive to noise and warped distortions. Experiments show that this algorithm is accurate and robust. © 2013 IEEE.

关键词： Signal analysis

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Fuzzy partition and correlation for image segmentation with differential evolution

IAENG International Journal of Computer Science

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IAENG International Journal of computer Science 2013年第3期40卷 164-172页

作者： Nie, Fangyan Zhang, Pingfeng Institute of Graphics and Image Processing Technology Hunan University of Arts and Science Changde 415000 China College of Computer Science and Technology Hunan University of Arts and Science Changde 415000 China

Thresholding-based techniques have been widely used in image segmentation. The selection of appropriate threshold is a very significant issue for image thresholding. In this paper, a new image histogram thresholding method based on fuzzy partition and maximum correlation criterion is presented. In the proposed approach, the regions, i.e. object and background, are considered ambiguous in nature, and hence the regions are transformed into fuzzy domain with membership functions. Then, the fuzzy correlations about regions are constructed and the optimal threshold is determined by searching an optimal parameter combination of the membership functions such that the correlation of the fuzzy partitions is maximized. Since the exhaustive search for all fuzzy parameter combinations is too costly, the differential evolution algorithm is introduced into fuzzy correlation image segmentation to solve this optimal problem adaptively. Experimental results on general images and infrared images demonstrate the effectiveness of the proposed method.

关键词： image segmentation

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Mechanism of a learning robot manipulator for laparoscopic surgical training

Mechanism of a learning robot manipulator for laparoscopic s...

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12th International Conference on Intelligent Autonomous Systems, IAS 2012

作者： Yang, Tao Liu, Jiang Huang, Weimin Su, Yi Yang, Liangjing Chui, Chee Kong Ang Jr., Marcelo H. Chang, Stephen K. Y. Dept. of Computer Graphics and Interface Dept. of Computer Vision and Image Understanding Institute for Infocomm Research Singapore Singapore Dept. of Computing Science Institute of High Performance Computing Singapore Singapore Dept. of Mechanical Engineering National University of Singapore Singapore Singapore Dept. of Surgery National University Hospital Singapore Singapore

ISBN: (纸本)9783642339318

This paper presents a robot manipulator for hand-over-hand guidance training of laparoscopic surgery. Details of the mechanical design, kinematic analysis and control mechanism of the robot are presented. The robot records motion of surgical tool manipulated by master surgeon, and provides physical guidance to the trainee based on the recorded motion. The robotic manipulator can accurately reproduce the five degree of freedom manipulation of laparoscopic instrument during surgery. A hybrid spherical mechanism is applied for decoupling and reproducing the motion of surgical tool to facilitate implementation of control mechanism. The manipulators for left and right hands are capable of precise execution of a recorded trajectory with observed maximum error of 2.12 mm and 2 mm respectively during an experiment on user interaction. © 2013 Springer-Verlag.

关键词： Laparoscopy

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Single Cluster PHD SLAM: Application to Autonomous Underwater Vehicles using Stereo Vision

Single Cluster PHD SLAM: Application to Autonomous Underwate...

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Oceans 2013 - Norway

作者： Sharad Nagappa Narcis Palomeras Chee Sing Lee Nuno Gracias Daniel E. Clark Joaquim Salvi Computer Vision and Robotics Group University of Girona Joint Research Institute in Signal and Image Processing Heriot-Watt University

ISBN: (纸本)9781479900022

This paper considers the application of feature-based simultaneous localisation and mapping (SLAM) using a random finite sets (RFS) framework for an autonomous underwater vehicle. SLAM allows for reduction in localisation error by tracking features which provide a fixed external reference. The SLAM problem is addressed here using a single-cluster probability hypothesis density (PHD) filter. The filter uses a particle approximation for the vehicle position with a conditional Gaussian mixture PHD for the feature map. Map features are selected as unique point features generated from a stereo camera on-board the vehicle. We demonstrate the improvement in localisation applying the algorithm to a dataset obtained in an indoor test tank.

关键词： Autonomous underwater vehicles Stereoviews supersonic low altitude missile underwater vehicles Automatic vehicle location Stereo cameras simultaneous localization and mapping

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Abstraction based access control framework using least ontology

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Advances in Information Sciences and Service Sciences 2012年第15期4卷 42-49页

作者： Kim, Yun-Sam Cho, Eun-Sun Image Processing Research Center Korea Institute of Science and Techonology Korea Republic of Dept.of Computer Science and Engineering Chungnam National University Korea Republic of

Context data is one of most important parts of every context-aware system. Context data is not only trigger of events but also result of these events. So, privacy of context is one of important issue of context-aware system. Established methods of privacy like RBAC are not efficient to context data because these methods cannot control context data itself. So, some methods add abstraction ontology to access control framework. Abstraction ontology control expose of context data. But, using ontology to control expose of context data also have some problems. One is reliability of abstracted value and the other is performance of context data. In this paper, we suggest abstraction based access control system which minimizes abstraction overhead. To do this, we classify context data newly first. Classification of context data is based on abstraction method. And then we propose abstraction method of context data. Few context data use abstraction ontology. But, many of context data do not use abstraction ontology and abstraction of these context data reduces abstraction cost.

关键词： Ontology

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