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International Conference on systems and Informatics (ICSAI)

作者： Feng Xue Xiaotao Wang School of Computer Science and Information Hefei University of Technology Hefei China State Key Laboratory of Virtual Reality Technology and System Beihang University Beijing China

To construct Anhui-Styled Architecture (ASA) models rapidly and automatically, we proposed an automatic modeling method by analyzing the basic structure of ASA in-depth. Firstly, we built modules' database, composition rule database and repository database of ASA. Then, we translated each module of architecture into a node of graph and traverse these nodes using Breadth-First Traversal(BFS) algorithm of Graph to get descript document of single building. Finally, large scale scene of ASA were constructed automatically by combine the descript document and large scale ground scenes. Experimental results show that our method is rapid and effective for constructing ASA models.

关键词： Solid modeling Buildings Computational modeling Databases Layout Analytical models Cities and towns

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Physically based simulation of solid objects' burning

Lecture Notes in Computer Science (including subseries Lectu...

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Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) 2012年 7145 LNCS卷 110-120页

作者： Liu, Shiguang An, Tai Gong, Zheng Hagiwara, Ichiro School of Computer Science and Technology Tianjin University Tianjin 300072 China State Key Lab of Virtual Reality Technology and System Beihang University Beijing 100191 China Department of Mechanical Science and Engineering Tokyo Institute of Technology Tokyo 152-8550 Japan

ISBN: (纸本)9783642290497

This paper presents a novel method for realistic simulation of solid objects' burning. The temperature field is first constructed based on combustion theories. Then, a temperature field motivated interaction model (TFMI) is proposed to simulate the interactions between the fire and the objects during burning. In TFMI, the decomposition of the objects is modeled by improving the level set method and the spreading of fire is calculated using the updated temperature field at each time step. Our method can deal with varied topologies of different objects during burning. The fire is simulated by adopting stable fluid method and integrated into the whole burning scenes. Finally, various solid objects' burning scenes are rendered automatically using the above model. The experiment results show the validity of our method. © 2012 Springer-Verlag Berlin Heidelberg.

关键词： Temperature

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Finger vein verification using Occurrence Probability Matrix (OPM)

Finger vein verification using Occurrence Probability Matrix...

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International Joint Conference on Neural Networks

作者： Darun Tang Beining Huang Rongfeng Li Wenxin Li Xiaoming Li Key Laboratory of Machine Perception (MOE) School of Electronics Engineering and Computer Science Peking University State Key Lab of Virtual Reality Technology and Systems Beihang University

ISBN: (纸本)9781467314886

We found that the discrepancy between different finger vein templates of the same finger affects the identification results more seriously than the similarity of templates of different fingers does. Some areas on templates have stable values while some other areas are variable. We propose the Occurrence Probability Matrix (OPM), which is a property of a finger, to define the stability. When matching two templates using OPM, the areas of higher stability make more contribution to the result and those of lower stability make less contribution. In this way, OPM can enhance the similarity of templates of the same finger and drop off the influence of the unsteady areas. In a finger vein verification system running for a long time, we can get enough templates of every finger to generate an effective OPM. But it does not mean that using more templates can get a better OPM. So, we fatherly propose a strategy to select typical templates purposely from all templates of a finger to calculate the OPM. Experimental results show that by simply using OPM calculated from all existing templates, the EER of the system is reduced from 9.8% to 7.6%. And by using the OPM calculated from selected typical templates by our strategy, the EER of the system is further reduced from 7.6% to 3.1%.

关键词： OPM Finger vein Template Stability Selection

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IEEE WIC ACM International Conference on Web Intelligence (WI)

作者： Zhao Wei Chunhe Xia Qing Wei Shan Yao Yujian Zhou State Key Laboratory of Virtual Reality Technology and System Key Laboratory of Beijing Network Technology School of Computer Science and Engineering Beihang University Beijing China Information Center of Ministry of Science and Technology The Ministry of Science and Technology of the Peoples Republic of China Beijing China

The transformation from high-level model description to low-level implementation for network survivability may lead to semantic inconsistency problem, since the method of transformation is based on symbolic transformation of machine which neglects semantics of proposed problem. Therefore, in order to analyze the semantic differences of transformation before and after and ensure the semantic consistency, this paper built an Ontology model of high-level model description and low-level implementation for network survivability. We proposed an Ontology-based multi-factor synthesized method which is used to analyze semantic similarity of multi-hierarchy text including high-level model description text and low-level implementation text. This method included the computation of type similarity of the text based on concept lattice, computation of content similarity of the text based on ontology and computation of structure similarity of the text based on inverse order pairs. The availability of the method is verified by experiments and its accuracy is proved by comparison with classic VSM algorithm, WeiSong algorithm, CF algorithm and professional value.

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Light Space Cascaded Shadow Maps Algorithm for Real Time Rendering

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Journal of Computer Science & technology 2011年第1期26卷 176-186页

作者：梁晓辉马上岑丽霞于卓 State Key Lab.of Virtual Reality Technology and Systems School of Computer Science and EngineeringBeihang University

Owing to its generality and efficiency, Cascaded Shadow Maps （CSMs） has an important role in real-time shadow rendering in large scale and complex virtual environments. However, CSMs suffers from redundant rendering problem -- objects are rendered undesirably to different shadow map textures when view direction and light direction are not perpendicular. In this paper, we present a light space cascaded shadow maps algorithm. The algorithm splits a scene into non-intersecting layers in light space, and generates one shadow map for each layer through irregular frustum clipping and scene organization, ensuring that any shadow sample point never appears in multiple shadow maps. A succinct shadow determination method is given to choose the optimal shadow map when rendering scenes. We also combine the algorithm with stable cascaded shadow maps and soft shadow algorithm to avoid shadow flicking and produce soft shadows. The results show that the algorithm effectively improves the efficiency and shadow quality of CSMs by avoiding redundant rendering, and can produce high-quality shadow rendering in large scale dynamic environments with real-time performance.

关键词： shadow mapping light space redundant rendering large scale dynamic environments

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Scalable and Identifier/Locator-Splitting Routing Protocol for Mobile Ad Hoc Networks

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China Communications 2012年第1期9卷 102-110页

作者： Wang Haiquan Chen Meng Hu Junshun Xia Chunhe Beijing Key Laboratory of Network Technology Beihang University Beijing 100191 P. R. China School of Computer Science and Engineering Beihang University Beijing 100191 P. R. China State Key Laboratory of Virtual Reality Technology and System Beihang University Beijing 100191 P. R. China School of So ware Beihang University Beijing 100191 P. R. China

In the traditional Intemet Protocol （IP） architecture, there is an overload of IP sermntic problems. Existing solutions focused mainly on the infrastructure for the fixed network, and there is a lack of support for Mobile Ad Hoc Networks （MANETs）. To improve scalability, a routing protocol for MANETs is presented based on a locator named Tree-structure Locator Distance Vector （TLDV）. The hard core of this routing method is the identifier/locator split by the Distributed Hash Table （DHT） method, which provides a scalable routing service. The node locator indicates its relative location in the network and should be updated whenever topology changes, kocator space ks organized as a tree-structure, and the basic routing operation of the TLDV protocol is presented. TLDV protocol is compared to some classical routing protocols for MANETs on the NS2 platform Results show that TLDV has better scalability. key words：

关键词： MANETs multi-hop routing identifi- er/locator split distributed hash tables

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Six degree-of-freedom haptic simulation of periodontal pathological changes

Six degree-of-freedom haptic simulation of periodontal patho...

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2012 IEEE/RSJ International Conference on Intelligent Robots and systems

作者： Dangxiao Wang Shuai Liu Xin Zhang Jing Xiao Jianxia Hou Yuru Zhang State Key Lab of Virtual Reality Technology and Systems Beihang University Beijing China Department of Computer Science University of North Carolina- Charlotte USA School and Hospital of Stomatology Peking University Beijing China

Geometric modeling and haptic simulation of pathological changes is an important topic for high-fidelity surgical simulators. In this paper, we introduce a constraint-based six degree-of-freedom (DOF) haptic simulation method incorporating multi-contact friction. We use this method to simulate periodontal operations on typical pathological tissues, including periodontal pocket and two kinds of calculi. A continuous collision detection method based on sphere-trees is proposed to avoid the pop-through phenomenon during tool manipulation against thin objects (such as small sized calculus adhered to the surface of the target tooth). For particle shaped calculus, a friction model is adapted to simulate decreasing frictions during the removal of the calculus. Experiments using a Phantom Premium 3.0 6DOF were carried out to validate the performance of our method. Stable haptic rendering and about 1 kHz update rate was maintained for all the operations, including depth measurement of the periodontal pocket and removal of the invisible block-shaped and particle-shaped calculi.

关键词： Calculus Haptic interfaces Force Friction Solid modeling Teeth Graphics

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Resource-distortion modeling for video streaming over mesh networks with priority-based packet scheduling

Resource-distortion modeling for video streaming over mesh n...

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

作者： Zhang, Yongfei Zhang, Yunsheng Qin, Shiyin He, Zhihai Beijing Key Lab. of Digital Media School of Computer Science and Engineering Beihang University Beijing 100191 China State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing 100191 China School of Automation Science and Electrical Engineering Beihang University Beijing 100191 China Graduate School at Shenzhen Tsinghua University Shenzhen 518055 China Department of Electrical and Computer Engineering University of Missouri Columbia MO 65211 United States

ISBN: (纸本)9781467316590

Video streaming over mesh networks operates under stringent network resource constraints, with a large number of video sessions competing for limited network resources. In this work, we aim to establish so-called resource-distortion models to characterize the inherent relationship between the allocated network resources to each video session and its end-to-end video distortion or presentation quality at the receiver end. We observed that priority-based packet scheduling has significant impact on such resource-distortion relationship. Using ANN-based learning methods, we develop an end-to-end packet delay bound violation (PDBV) probability model for video streaming over multi-hop networks with priority-based packet scheduling. We then derive a quadratic video transmission distortion model to capture the unique behavior of priority-based packet scheduling and its impact on the end-to-end video distortion. Based on these resource-distortion models, we are able to predict the end-to-end distortion for video streaming over multi-hop networks with priority-based packet scheduling. Our extensive experimental results demonstrate that the proposed method is very accurate. © 2012 IEEE.

关键词： Video streaming

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Automatic skeleton generation and character skinning

Automatic skeleton generation and character skinning

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IEEE International Symposium on VR Innovation

作者： Cheng, Wang Cheng, Ren Xiaoyong, Lei Shuling, Dai State Key Lab of Virtual Reality and System Beihang University China

ISBN: (纸本)9781457700538

An articulated character skinning usually requires manual skeleton embedding and vertex weight painting. We propose a fast and automatic method for skeleton generation and character skinning. First, we segment the given character mesh by the sequential steps of NCV(normal characteristic value) computation, segment points refinement, and principal component analysis of segment clusters. Then, two types of joints and a skeleton are generated based on the mesh segmentation result. Furthermore, we compute weights of vertices influenced by skeleton automatically and then skinning the character mesh by skeleton driven and muscle pushing algorithm. Experimental results show that our method achieves both high visual quality and fast speed. It could be used in character animation and VR real time applications. © 2011 IEEE.

关键词： virtual reality

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Visualizing timelines: Evolutionary summarization via iterative reinforcement between text and image streams 12

Visualizing timelines: Evolutionary summarization via iterat...

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21st ACM International Conference on Information and Knowledge Management, CIKM 2012

作者： Yan, Rui Wan, Xiaojun Lapata, Mirella Zhao, Wayne Xin Cheng, Pu-Jen Li, Xiaoming Dept. of Computer Science and Information Engineering National Taiwan University Taipei 10617 Taiwan Institute of Computer Science and Technology Peking University Beijing 100871 China Institute for Language Cognition and Computation University of Edinburgh Edinburgh EH8 9AB United Kingdom Dept. of Computer Science and Technology Peking University Beijing 10087 China State Key Lab. of Virtual Reality Tech. and Systems Beihang University Beijing 100083 China

ISBN: (纸本)9781450311564

We present a novel graph-based framework for timeline summarization, the task of creating different summaries for different timestamps but for the same topic. Our work extends timeline summarization to a multimodal setting and creates timelines that are both textual and visual. Our approach exploits the fact that news documents are often accompanied by pictures and the two share some common content. Our model optimizes local summary creation and global timeline generation jointly following an iterative approach based on mutual reinforcement and co-ranking. In our algorithm, individual summaries are generated by taking into account the mutual dependencies between sentences and images, and are iteratively refined by considering how they contribute to the global timeline and its coherence. Experiments on real-world datasets show that the timelines produced by our model outperform several competitive baselines both in terms of ROUGE and when assessed by human evaluators. © 2012 ACM.

关键词： Reinforcement

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