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Video motion stitching using trajectory and position similarities

Science China(Information Sciences) 2012年第3期55卷 600-614页

作者： CHEN XiaoWu, LI Qing , LI Xin & ZHAO QinPing State key laboratory of virtual Reality technology and Systems, School of computer Science and Engineering, Beihang University, Beijing 100191, China 1. State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and Engineering Beihang University Beijing 100191 China

Stitching motions in multiple videos into a single video scene is a challenging task in current video fusion and mosaicing research and film production. In this paper, we present a novel method of video motion stitching based on the similarities of trajectory and position of foreground objects. First, multiple video sequences are registered in a common reference frame, whereby we estimate the static and dynamic backgrounds, with the former responsible for distinguishing the foreground from the background and the static region from the dynamic region, and the latter functioning in mosaicing the warped input video sequences into a panoramic video. Accordingly, the motion similarity is calculated by reference to trajectory and position similarity, whereby the corresponding motion parts are extracted from multiple video sequences. Finally, using the corresponding motion parts, the foregrounds of different videos and dynamic backgrounds are fused into a single video scene through Poisson editing, with the motions involved being stitched together. Our major contributions are a framework of multiple video mosaicing based on motion similarity and a method of calculating motion similarity from the trajectory similarity and the position similarity. Experiments on everyday videos show that the agreement of trajectory and position similarities with the real motion similarity plays a decisive role in determining whether two motions can be stitched. We acquire satisfactory results for motion stitching and video mosaicing.

关键词： video fusion video mosaicing video registration background estimation motion stitching

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Minkowski sum modeling of polyhedra based on VRML

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ICIC Express Letters 2013年第2期7卷 455-460页

作者： Zhang, Jianfei Guo, Xijuan Geng, Qingjia Information Science and Engineering College Yanshan University No. 438 Hebei Ave. Qinhuangdao 066004 China The Key Laboratory for Computer Virtual Technology and System Integration of HeBei Province No. 438 Hebei Ave. Qinhuangdao 066004 China Computer and Control Engineering College Qiqihar University No. 42 Wenhua Street Qiqihar 161006 China

On the basis of the introduction to basic methods of the geometry modeling based on virtual reality modeling language (VRML) and the concepts of Minkowski sum computation of polyhedra, we present a method of Minkowski sum computation and three dimensional modeling based on VRML. The method can simplify Minkowski sum computation of general polyhedra, and experimental results indicate that this method can calculate Minkowski sum of general polyhedra much faster and realize three-dimensional representation more accurately. This method can provide important technical references for Minkowski sum visualization of polyhedra. © 2013 ISSN 1881-803X.

关键词： Geometry

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Fault Tolerance and Recovery for Group Communication Services in Distributed Networks

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Journal of computer Science & technology 2012年第2期27卷 298-312页

作者：王跃华周忠 Ling Liu 吴威 State Key Laboratory of Virtual Reality Technology and Systems Beihang UniversityBeijing 100191China School of Computer Science and Engineering Beihang UniversityBeijing 100191China College of Computing Georgia Institute of TechnologyAtlanta 30332U.S.A.

Group communication services （GCSs） are becoming increasingly important as a wide field of promising applications has emerged to serve millions of users distributed across the ***,it is challenging to make the service fault tolerance and scalable to fulfill the voluminous demand of users in a distributed network （DN）.While many reliable group communication protocols have been dedicated to addressing such a challenge so as to accommodate the changes in the network,they are often costly or require complicated strategies to handle the service interruptions caused by node departures or link failures,which hinders the service *** this paper,we present two schemes to address the *** first one is a location-aware replication scheme called NS,which makes replicas in a dispersed fashion that enables the services on nodes to gain immunity of failures with different patterns （e.g.,network partition and single point failure） while keeping replication overhead *** second one is a novel failure recovery scheme that exploits the independence between service recovery and structure recovery in time domain to achieve quick failure *** simulation results indicate that the two proposed schemes outperform the existing schemes and simple alternative schemes in service success rate,recovery latency,and communication cost.

关键词： fault tolerance failure recovery replication location group communication

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Rain scenes rendering algorithm combining metaball with mass-spring surface

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Jilin Daxue Xuebao (Gongxueban)/Journal of Jilin University (Engineering and technology Edition) 2013年第SUPPL.1期43卷 230-234页

作者： Lyu, Meng-Ya Zheng, Xuan Tang, Yong College of Information Science and Engineering Yanshan University Qinhuangdao 066004 China The Key Laboratory for Computer Virtual Technology and System Integration of HeBei Province Qinhuangdao 066004 China

To solve the problems such as unreal effects, incomplete details in the rain scene, an algorithm to simulate water surface after rain hitting by combining Meatball with mass-spring water surface was presented. First, the raindrops model was estabished with particle system combining textures, and the water surface model was established with the mass-spring model. Secondly, the algorithm animated half globular bubbles after rain hitting with Meatball. Thirdly, water splash was simulated by means of the particle system and a gradual thinning and syncretizing technique. Finally, with the help of Cg language, the reflection and the refraction effect on the water surface, globular bubbles and water splash were simulated. The experiment shows that this approach can be used to simulate rain scenes efficiently and realistically.

关键词： Rain

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Data stream clustering algorithm based on spatial directed graph

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Advances in Information Sciences and Service Sciences 2012年第20期4卷 241-249页

作者： Ren, Jiadong Yuan, Xuemei Dong, Jun College of Information Science and Engineering Yanshan University Qinhuangdao Hebei 066004 China The Key Laboratory for Computer Virtual Technology and System Integration of Hebei Province Qinhuangdao City 066004 China

Recently, the grid-density based clustering has become one of the major issues among all of the clustering approaches, it has special advantages over other clustering algorithms, such as less computation and the ability of clustering with arbitrarily shape, which are particularly useful for the data stream clustering. This paper defines a spatial directed graph named Grid-Based Graph (GBG) to store the non-empty grids in data space, and proposes a data stream clustering algorithm based on spatial directed graph GBGSClu (Grid-Based Graph Stream Clustering). GBG graph composes of vertices and directed edges, if a vertex A has a neighboring dense vertex B, and then there is a directed edge from vertex B to A in GBG. The algorithm maps the data stream into the non-empty vertices online, updates the vertices' feature vectors with the arriving of data stream, deletes the sparse vertices every gap time, generates GBG graph when the clustering quest coming and finally clusters on the current structure. The eventual clustering results can be obtained by only checking the vertices' in-degree which can reduce the computation needed in clustering. The validity and efficiency of GBGSClu algorithm have been tested and verified by clustering on real and synthetic datasets.

关键词： Directed graphs

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Correlation technology of suturing procedure in virtual surgery

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Jilin Daxue Xuebao (Gongxueban)/Journal of Jilin University (Engineering and technology Edition) 2013年第SUPPL.1期43卷 16-20页

作者： Lyu, Meng-Ya Han, Yu-Fang Tang, Yong College of Information Science and Engineering Yanshan University Qinhuangdao 066004 China Key Laboratory for Computer Virtual Technology and System Integration of Hebei Province Yanshan University Qinhuangdao 066004 China

Aiming at the difficulty of achieving interactive simulation between soft tissue and suture, a method to simulate suturing procedure in virtual surgery was proposed. Firstly, mass-spring model was used as the physical model for soft tissue. In order to perform the relative motion between two masses of soft tissue realistically, an internal friction coefficient was introduced first. Secondly, the interaction of suture and soft tissue was aralyzed. A simple linear mass-spring model with following the leader algorithm was used to model the suture. A stress aralysis was carried out, when the suture touch the soft tissue, so the interaction process was close to physical reality. The movement of the whole suture computed by following the leader algorithm gave good performance in suture's rigidity characteristics. Finally, the interaction of the two deformable objects in a continuous pattern suture was considered, for each node of the soft tissue model, the node that attached to it was stored. This information can be used to compute the soft tissue deformation well. Experiment shows that it is realistical to simulate the soft tissue deformation and suture. meanwhile, the simulation is in real time.

关键词： Deformation

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Clustering based search algorithm for motion estimation

Clustering based search algorithm for motion estimation

引用

2012 13th IEEE International Conference on Multimedia and Expo, ICME 2012

作者： Chen, Ke Zhou, Zhong Wu, Wei State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and Engineering Beihang University Beijing China

ISBN: (纸本)9781467316590

Motion estimation is the key part of video compression since it removes the temporal redundancy within frames and significantly affects the encoding quality and efficiency. In this paper, a novel fast motion estimation algorithm named Clustering Based Search algorithm is proposed, which is the first to define the clustering feature of motion vectors in a sequence. The proposed algorithm periodically counts the motion vectors of past blocks to make progressive clustering statistics, and then utilizes the clusters as motion vector predictors for the following blocks. It is found to be much more efficient for one block to find the best-matched candidate with the predictors. Compared with the mainstream search algorithms, this algorithm is almost the most efficient one, 35 times faster in average than the full search algorithm, while its mean-square error is even competitively close to that of the full search algorithm. © 2012 IEEE.

关键词： Motion estimation

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Radiance-based color calibration for image-based modeling with multiple cameras

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Science China(Information Sciences) 2012年第7期55卷 1509-1519页

作者： ZHAO Xu 1,2 ,ZHOU Zhong 1,2 & WU Wei 1,2 1 State key laboratory of virtual Reality technology and Systems,Beihang University,Beijing 100191,China 2 School of computer Science and Engineering,Beihang University,Beijing 100191,China 1. State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing 100191 China2. School of Computer Science and Engineering Beihang University Beijing 100191 China

Photo-consistency estimation is an important part for many image-based modeling *** paper presents a novel radiance-based color calibration method to reduce the uncertainty of photo-consistency estimation across multiple *** idea behind our method is to convert colors into a uniform radiometric color space in which multiple image data are *** results demonstrate that our method can achieve comparable color calibration effect without adjusting camera parameters and is more robust than other existing ***,we obtain an auto-determined threshold for photo-consistency check,which will lead to a better performance than existing photo-consistency based reconstruction algorithms.

关键词： color calibration photo-consistency estimation multi-camera system image-based modeling

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Geometric algebra support vector machine for pattern recognition

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ICIC Express Letters 2013年第3 B期7卷 1031-1035页

作者： Wang, Jinjia Zhang, Cuihua Lu, Haitao Hong, Wenxue College of Information Science and Engineering Yanshan University No. 438 Hebei Ave. Qinhuangdao 066004 China Key Laboratory for Computer Virtual Technology and System Integration of Hebei Province Yanshan University No. 438 Hebei Ave. Qinhuangdao 066004 China College of Electrical Engineering Yanshan University No. 438 Hebei Ave. Qinhuangdao 066004 China

Geometric algebra is the promotion of real, complex, quaternion, and has been successfully applied in physics, computer graphics, and other fields. The support vector machine (SVM) has been successfully used in the field of pattern recognition. On the basis of the Clifford support vector machine (CSVM), we improve support vector machine based on the principle of geometric algebra. We research the key technologies in training. The experimental results of the Iris data and Breast Cancer data set prove our ideas, and the correct recognition rates are 96% and 97.8%. © 2013 ICIC International.

关键词： Support vector machines

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Displacement residual based DDM matching algorithm

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Science China(Information Sciences) 2012年第9期55卷 2090-2101页

作者： ZHANG Lin 1,2,ZHOU Zhong 1,2,LIU Lin 1,2 & WU Wei 1,2 1 State key laboratory of virtual Reality technology and Systems,Beihang University,Beijing 100191,China 2 School of computer Science and Engineering,Beihang University,Beijing 100191,China 1. State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing 100191 China2. School of Computer Science and Engineering Beihang University Beijing 100191 China

High level architecture(HLA) is the prevailing standard for modeling and *** data distribution management(DDM) service of HLA is defined for reducing the delivery of irrelevant *** key in DDM implementation is the region overlap computation,*** matching between update and subscription *** algorithms usually make a compromise between region fidelity and network *** paper takes both the matching algorithm efficiency and bandwidth cost into *** main contributions are:1) illustrating the relationship between region changes and overlap changes,as helps reduce the number of region matching and then improves the total matching efficiency;2) classifying region updates into two types of data expression,snapshot and *** network traffic will be reduced by transmitting only residual data instead of full region representations ***,a region matching algorithm called displacement residual-based DDM matching(DRBM) is proposed in the *** analysis,algorithm implementation and experiment evaluation are *** results show that DRBM provides better matching performance and significant network payload reductions especially when there is a large number of changing regions.

关键词： distributed simulation high level architecture data distribution management region snapshot region residual

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