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Keeping speed and distance for aligned motion

Physical Review E 2015年第1期91卷 012807-012807页

作者： Illés J. Farkas Jeromos Kun Yi Jin (金祎) Gaoqi He (何高奇) Mingliang Xu (徐明亮) MTA-ELTE Statistical and Biological Physics Research Group (Hungarian Academy of Sciences) Pázmány Péter sétány 1A Budapest 1117 Hungary Regional Knowledge Center ELTE Faculty of Sciences Irányi Dániel u. 4. Székesfehérvár 8000 Hungary Department of Biological Physics Eötvös University Pázmány Péter sétány 1A Budapest 1117 Hungary Department of Computer Science and Engineering East China University of Science and Technology 130 Meilong Road Shanghai 200237 China State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing 100191 China School of Information Engineering Zhengzhou University 100 Science Avenue Zhengzhou 450001 China

The cohesive collective motion (flocking, swarming) of autonomous agents is ubiquitously observed and exploited in both natural and man-made settings, thus, minimal models for its description are essential. In a model with continuous space and time we find that if two particles arrive symmetrically in a plane at a large angle, then (i) radial repulsion and (ii) linear self-propelling toward a fixed preferred speed are sufficient for them to depart at a smaller angle. For this local gain of momentum explicit velocity alignment is not necessary, nor are adhesion or attraction, inelasticity or anisotropy of the particles, or nonlinear drag. With many particles obeying these microscopic rules of motion we find that their spatial confinement to a square with periodic boundaries (which is an indirect form of attraction) leads to stable macroscopic ordering. As a function of the strength of added noise we see—at finite system sizes—a critical slowing down close to the order-disorder boundary and a discontinuous transition. After varying the density of particles at constant system size and varying the size of the system with constant particle density we predict that in the infinite system size (or density) limit the hysteresis loop disappears and the transition becomes continuous. We note that animals, humans, drones, etc., tend to move asynchronously and are often more responsive to motion than positions. Thus, for them velocity-based continuous models can provide higher precision than coordinate-based models. An additional characteristic and realistic feature of the model is that convergence to the ordered state is fastest at a finite density, which is in contrast to models applying (discontinuous) explicit velocity alignments and discretized time. To summarize, we find that the investigated model can provide a minimal description of flocking.

关键词： Autonomous agents

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Sparse Dictionary Learning for Edit Propagation of High-resolution Images

Sparse Dictionary Learning for Edit Propagation of High-reso...

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IEEE Conference on computer vision and Pattern Recognition

作者： Xiaowu Chen Dongqing Zou Jianwei Li Xiaochun Cao Qinping Zhao Hao Zhang State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and Engineering Beihang University Institute of Information Engineering Chinese Academy of Sciences Simon Fraser University

ISBN: (纸本)9781479951192

We introduce a method of sparse dictionary learning for edit propagation of high-resolution images or video. Previous approaches for edit propagation typically employ a global optimization over the whole set of image pixels, incurring a prohibitively high memory and time consumption for high-resolution images. Rather than propagating an edit pixel by pixel, we follow the principle of sparse representation to obtain a compact set of representative samples (or features) and perform edit propagation on the samples instead. The sparse set of samples provides an intrinsic basis for an input image, and the coding coefficients capture the linear relationship between all pixels and the samples. The representative set of samples is then optimized by a novel scheme which maximizes the KL-divergence between each sample pair to remove redundant samples. We show several applications of sparsity-based edit propagation including video recoloring, theme editing, and seamless cloning, operating on both color and texture features. We demonstrate that with a sample-to-pixel ratio in the order of 0.01%, signifying a significant reduction on memory consumption, our method still maintains a high-degree of visual fidelity.

关键词： Image color analysis Dictionaries Equations Mathematical model Cloning Encoding Optimization

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Multi-scale local features based on anisotropic heat diffusion and global eigen-structure

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中国科学：信息科学（英文版） 2013年第11期56卷 53-62页

作者： LI Shuai QIN Hong HAO AiMin State Key Laboratory of Virtual Reality Technology and Systems Beihang UniversityBeijing 100191 China School of Biological Science and Medical Engineering Beihang UniversityBeijing 100191 China Department of Computer Science State University of New York at Stony BrookStony Brook NY 11794-4400 USA State Key Laboratory of Virtual Reality Technology and Systems Beihang UniversityBeijing 100191 China

Multi-scale local feature detection enables downstream registration and recognition tasks in medical image analysis. This paper articulates a novel robust method for multi-scale local feature extraction on volumetric data. The central idea is the elegant unification of local/global eigen-structures within the powerful framework of anisotropic heat diffusion. First, the local vector field is constructed by way of Hessian matrix and its eigenvectors/eigenvalues. Second, anisotropic heat kernels are computed using the vector field’s global graph Laplacian. Robust local features are manifested as extrema across multiple time scales, serving as volumetric heat kernel signature. To tackle the computational challenge for massive volumetric data, we propose a multiresolution strategy for hierarchical feature extraction based on our feature-preserving down-sampling approach. As a result, heat kernels and local feature identification can be approximated at a coarser level first, and then are pinpointed in a localized region at a finer resolution. Another novelty of this work lies at the initial heat design directly using local eigenvalue for anisotropic heat diffusion across the volumetric domain. We conduct experiments on various medical datasets, and draw comparisons with 3D SIFT method. The diffusion property of our local features, which can be interpreted as random walks in statistics, makes our method robust to noise, and gives rise to intrinsic multi-scale characteristics.

关键词： volumetric heat kernel anisotropic diffusion multi-scale local feature local/global eigen-structure volumetric image

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Data-driven season characteristic enhancement of natural image

Data-driven season characteristic enhancement of natural ima...

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2013 7th International Conference on Image and Graphics, ICIG 2013

作者： Ding, Feng Li, Jianwei Zou, Dongqing Chen, Xiaowu State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and Engineering Beihang University Beijing China

ISBN: (纸本)9780769550503

We present a system of creating new scenes in different seasons from an input image captured in a particular season by stylizing it according to similar images in our library which includes a vast number of different season scenes and objects. Firstly, we transfer the color appearance of the input scene in accordance with the color style of other seasons scenes by using color transfer approach. Secondly, user scribbles are used to guide the detection of repeated elements in the input image and geometric information of these detected elements are obtained. Then context-sensitive objects of specified class that match most of the required properties are retrieved from our library and edited according to the geometric information of the specified elements in the scene, such as inserting new objects into the scene or replacing objects by new ones. After that, a repeated-elements-based modification duplication scheme is proposed and implemented to semi-automatically propagate the user-specified objects modification. Finally, blending is applied to the inserted objects to achieve consistency with the target scene in illumination. The main contribution of this work is that we present a complete system to create new scenes of different seasons. © 2013 IEEE.

关键词： Color

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Facial performance illumination transfer from a single video using interpolation in non-skin region

Facial performance illumination transfer from a single video...

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作者： Wu, Hongyu Chen, Xiaowu Yang, Mengxia Fang, Zhihong State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and Engineering Beihang University Beijing China

This paper proposes a novel video-based method to transfer the illumination from a single reference facial performance video to a target one taken under nearly uniform illumination. We first filter the key frames of the reference and the target face videos with an edge-preserving filter. Then, the illumination component of reference key frame is extracted through dividing the filtered reference key frames by the corresponding filtered target key frames in skin region. The differences in non-skin region caused by different expressions between the reference and target face may bring about artifacts. Therefore, we interpolate the illumination component of the non-skin region by that of the surrounded skin region to ensure the spatial smoothness and consistency. After that, the illumination components of key frames are propagated to non-key frames to ensure the temporal consistency between the two adjacent frames. We obtain convincing results by transferring the illumination effects of a single reference facial performance video to a target one with the spatial and temporal consistencies preserved. Copyright © 2013 John Wiley & Sons, Ltd.

关键词： Interpolation

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HLA based high-performance visualized simulation with MATLAB seamlessly embedded

HLA based high-performance visualized simulation with MATLAB...

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2013 4th International Conference on Material and Manufacturing technology, ICMMT 2013

作者： Zhang, Heng Yuan Xiong, Wei Fan, Peng Shan State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and Engineering Beihang University Beijing China The Academy of Equipment

ISBN: (纸本)9783037857526

In order to build multi-domain collaborative simulation systems, the method of making MATLAB programs join into HLA/RTI based distributed interaction simulation system needs to be studied. Aiming at giving full play to the advent-ages of MATLAB in visualization and engineering computing, improving the efficiency of collaborative simulation systems, this paper has proposed a method making MATLAB programs and SIMULINK modules seamlessly join into HLA/RTI based simulation system. The principles of the method are elaborated, and the designs of the related modules are introduced. The demonstrations and testing results show that the method could fully execute the visualized simula-tion functions of MATLAB, and has advantage in simulation efficiency over existing methods. © (2013) Trans Tech Publications, Switzerland.

关键词： MATLAB

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Visualization services for multidisciplinary experiments on cloud-based virtual educational platform

Visualization services for multidisciplinary experiments on ...

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2013 IEEE International Conference on Green Computing and Communications and IEEE Internet of Things and IEEE Cyber, Physical and Social Computing, GreenCom-iThings-CPSCom 2013

作者： Jia, Guodong Chen, Xiaowu Li, Faming Pan, Rongjiang State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and Engineering Beihang University Beijing China School of Computer Science and Technology Shandong University Ji'nan China

ISBN: (纸本)9780769550466

With the advent of cloud computing in recent years, many people in the industry or colleges have pay their attention on it. In this work, we developed three visualization services for multidisciplinary experiments on a cloud-based virtual educational platform, which delivers "Software as a Service (SaaS)" over the internet. This platform integrates virtual experiment softwares distributed on the Internet, and delivers virtual experiment as a service to users. Our visualization services play a role for uniformly modeling virtual experiment instrument, building virtual experiment scene and visualizing virtual experiment result. More than 60 virtual experiment instruments are modeled and 18 virtual experiment scenes covering 5 disciplines are built. The user feedback demonstrates the usefulness of this work. © 2013 IEEE.

关键词： Visualization

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Annotating web images by combining label set relevance with correlation

Annotating web images by combining label set relevance with ...

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14th International Conference on Web-Age Information Management, WAIM 2013

作者： Tian, Feng Shen, Xukun State Key Laboratory of Virtual Reality Technology and Systems Beihang University 100191 Beijing China School of Computer and Information Technology Northeast Petroleum University 163318 Daqing China

ISBN: (纸本)9783642385612

Image annotation can significantly facilitate web image search and organization. Although it has been studied for years by the computer vision and machine learning communities, image annotation is still far from practical. Existing example-based methods are usually developed based on label co-occurrence information. However, due to the neglect of the associated label set's internal correlation and relevance to image, the annotation results of previous methods often suffer from the problem of label ambiguity and noise, which limits the effectiveness of these labels in search and other applications. To solve the above problems, a novel model-free web image annotation approach is proposed in this paper, which consider both the relevance and correlation of the assigned label set. First, measures that can estimate the label set relevance and internal correlation are designed. Then, according to the above calculations, both factors are formulated into an optimization framework, and a search algorithm is proposed to find a label set as the final result, which reaches a reasonable trade-off between the relevance and internal correlation. Experimental results on benchmark web image data set show the effectiveness and efficiency of the proposed algorithm. © 2013 Springer-Verlag Berlin Heidelberg.

关键词： Image annotation

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The implementation of virtual studio laboratory based on web

The implementation of virtual studio laboratory based on web

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3rd International Conference on Materials Science and Information technology, MSIT 2013

作者： Zhao, Ya Liu, Xian Mei Tian, Feng Tian, Feng School of Computer and Information Technology NorthEast Petroleum University Daqing 163318 China Ministry of Education Key Laboratory of Virtual Reality Technology Beihang University Beijing 100083 China

ISBN: (纸本)9783037857700

The studio has extraordinary meaning of the personnel training of the specialty. According to the actuality and application demand of colleges and universities, we plan to construct a virtual studio laboratory. The paper introduces the system functional components of virtual studio laboratory, elaborates the realization of technologies of virtual studio laboratory, analyses the virtual studio laboratory's application meaning in teaching in the end. Appling the virtual studio laboratory in teaching, we can acquire well teaching effect. The virtual studio laboratory has definite promotional value, can be used in the education and teaching of film and television producing extensively. © (2013) Trans Tech Publications, Switzerland.

关键词： Laboratories

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Image annotation with weak labels

Image annotation with weak labels

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14th International Conference on Web-Age Information Management, WAIM 2013

ISBN: (纸本)9783642385612

In this paper, we address the problem of image annotation when the given labels of training image are incomplete, inaccurate, and unevenly distributed, in the form of weak labels, which is frequently encountered when dealing with large scale web image training set. We introduce a progressive semantic neighborhood learning approach that explicitly addresses the challenge of learning from weakly labeled image by searching image's semantic consistent neighborhood. Neighbors in image's semantic consistent neighborhood have global similarity, partial correlation, conceptual similarity along with semantic balance. We also present an efficient label inference algorithm to handle noise by minimizing the neighborhood reconstruction error. Experiments with different data sets show that the proposed framework is more effective than the state-of-the-art algorithms in dealing with weakly labeled datasets. © 2013 Springer-Verlag Berlin Heidelberg.

关键词： Image annotation

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