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Light space parallel-split shadow maps based on programmable GPUs

Jisuanji Fuzhu Sheji Yu Tuxingxue Xuebao/Journal of Computer-Aided Design and Computer Graphics 2010年第3期22卷 388-395页

作者： Ma, Shang Liang, Xiaohui Yu, Zhuo Ren, Wei State Key Laboratory of Virtual Reality Technology and System School of Computer Science and Engineering Beihang University Beijing 100191 China

Parallel-split shadow maps (PSSM) suffers from redundant rendering that unnecessarily renders same objects to multiple shadow map textures, when the light's direction and the camera's view direction are not perpendicular. To solve this problem, this paper presents a light space parallel-split shadow maps algorithm (LiSPSSM). The algorithm first divides the scene into certain layers that do not intersect each other by light's frustums in light space, and generates one shadow map for each layer to ensure that any shadow map does not have the same sample points. Then a faster synthesizing scene shadow method, which avoids operations of pixel layer determination, is given to improve GPU's efficiency. The results show that LiSPSSM effectively addresses the redundant rendering problem in PSSM and improves the efficiency and quality of real-time shadow rendering.

关键词： Graphics processing unit

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A Method of Stereo Vision Matching Based on OpenCV

A Method of Stereo Vision Matching Based on OpenCV

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2010 International Conference on Audio,Language and Image Processing(2010年音频、语言与图像处理国际会议 ICALIP 2010)

作者： Ling Zou Yan Li State key laboratory of virtual reality technology and system Beihang University

ISBN: (纸本)9781424458653

Stereo vision is an important branch of the research area in computer vision. Among the techniques of stereo vision, binocular stereo vision which is based on processing two images remains a research hotspot. Binocular stereo vision directly simulates the manner of human eyes observing one scene from two different viewpoints. By using the principle of triangulation, the disparities of a number of 3D points mapped to pixels in two images are computed. Then the visual information of depth is also recovered. The object surface shape can be acquired using these disparities. In this paper, a pair of common web cameras is used to collect images. Based on OpenCV, the calibration algorithm of stereo vision is achieved. Stereo rectify/and stereo matching algorithm are also rapidly and efficiently implemented. Finally, the depth information of object is obtained.

关键词： Stereoviews images computer vision BINOCULARS

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A Real-time Collision Detection between virtual and Real Objects Based on Three-dimensional Tracking of Hand

A Real-time Collision Detection between Virtual and Real Obj...

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2010 International Conference on Audio,Language and Image Processing(2010年音频、语言与图像处理国际会议 ICALIP 2010)

作者： Yan Li Xukun Shen State key laboratory of virtual reality technology and system Beihang University

ISBN: (纸本)9781424458561

In the working environment of argument reality, users interact with virtual objects by hands. Making realtime collision detection between virtual and real objects is very essential to enhance the immersion and authenticity of the environment. In this paper, the key points of hand are marked by color block. We use a pair of common web cameras to collect images and track the points. Then the stereo vision calibration algorithm is achieved. We get hand positioning by calculating the disparity of key points between two images and restoring the threedimensional position. At the same time, the virtual object models are divided to a binary tree and pretreated by the OBB bounding box. At last, the accurate collision detection is achieved by calculating the relative position between real hand and virtual objects real-time.

关键词： Hand virtual Collision detection Collision avoidance virtual target web camera Real number images

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Topic modeling ensembles

HP Laboratories Technical Report

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HP laboratories Technical Report 2010年第158期

作者： Shen, Zhiyong Luo, Ping Yang, Shengwen Shen, Xukun Hewlett Packard Labs China State Key Laboratory of Virtual Reality Technology and system China

In this paper we propose a framework of topic modeling ensembles, a novel solution to combine the models learned by topic modeling over each partition of the whole corpus. It has the potentials for applications such as distributed topic modeling for large corpora, and incremental topic modeling for rapidly growing corpora. Since only the base models, not the original documents, are required in the ensemble, all these applications can be performed in a privacy preserving manner. We explore the theoretical foundation of the proposed framework, give its geometric interpretation, and implement it for both PLSA and LDA. The evaluation of the implementations over the synthetic and real-life data sets shows that the proposed framework is much more efficient than modeling the original corpus directly while achieves comparable effectiveness in terms of perplexity and classification accuracy. © Copyright The 18th ACM Conference on Information and Knowledge Management, 2009.

关键词： Classification (of information)

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Real-time cutting method for soft tissue based on TLED algorithm

Real-time cutting method for soft tissue based on TLED algor...

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International Conference on Computer Engineering and technology

作者： Wang, He-Xiang Hao, Ai-Min Li, Duo Liu, Xue-Mei State Key Laboratory of Virtual Reality Technology and System Beihang University Beijing China Department of Information and Engineering North China Institute of Water Conservancy and Hydroelectric Power Zhengzhou China

ISBN: (纸本)9781424463503

Surgery simulation system can provide a safe virtual training environment. Cutting of soft tissue plays a very important role in the system. During the operation, the soft tissue exhibits nonlinear property and topology change of the operated tissue usually causes the failure of the pre-computed quantity. The above reasons make the simulation of the real-time cutting a challenging task. This paper proposes a new cutting method, based on TLED nonlinear finite element algorithm which deals with real time simulation of deformation. The method combines virtual node algorithm and TLED algorithm, pre-computes related quantities on the element level and locally modifies topology of soft tissue after cutting, avoiding re-computation of pre-computed data. Experiments display its ability to simulate cutting of soft tissue with nonlinear property within real time. © 2010 IEEE.

关键词： Finite element method

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2010 International Conference on Educational and Information technology, ICEIT 2010

作者： Hao, Senshen Jiao, Jian Xia, Chunhe Li, Xiaojian Yao, Shan State Key Laboratory of Virtual Reality Technology and System School of Computer Science and Engineering Beihang University Beijing China Beijing Key Laboratory of Network Technology School of Computer Science and Engineering Beihang University Beijing China

ISBN: (纸本)9781424480340

In order to effectively deal with large-scale attacks on computer networks, Computer Network Defense (CND) policy refinement based on descriptive language is wildly used. However, it's very difficult to figure out the semantic discrepancies between the measures and the predefined policy after the calculation with symbols by computers. A new method is presented to solve the discordance of semantic between the measures and the predefined policy automatically. Based on the establishment of the ontology of CND policy and measure (CNDPM), the CND policy and measure semantic similarity analysis model (CNDPMSSAM) is established, and then the termination of the two main components of CNDPMSSAM are proofed by the putdown automaton, and the prototype system of CNDPMSSAM is implemented. At last, we validate the validity of this method on analyzing semantic similarity of transferring from Computer Network Defense Policy Specification Language (CNDPSL) to Defense Measure Description Language (DMDL) with experiments. © 2010 IEEE.

关键词： Ontology

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Descriptive model of peer-to-peer botnet structures

Descriptive model of peer-to-peer botnet structures

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2010 International Conference on Educational and Information technology, ICEIT 2010

作者： Duan, Junfeng Jiao, Jian Xia, Chunhe Yao, Shan Li, Xiaojian State Key Laboratory of Virtual Reality Technology and System School of Computer Science and Engineering Beihang University Beijing China Beijing Key Laboratory of Network Technology School of Computer Science and Engineering Beihang University Beijing China

ISBN: (纸本)9781424480340

Peer-to-peer (P2P) Botnets, which are more resilient and robust than centralized botnets, have emerged as the peer-to-peer technology evolves. Better understanding of this new phenomenon will help researchers develop detection and mitigation methods. Most of existing work is case study of typical P2P botnets. In this paper, we focus on systematically analyzing structures of P2P botnets. We propose a descriptive model of P2P botnet structures, which consists of features of P2P bot, definitions of structures, and structural properties. Firstly, we detail two key functionalities of P2P bot, command-and-control (C&C) functionality and peer-to-peer (P2P) functionality, and give several features of P2P bot. And then, we define two structures of P2P botnets: C&C structure and P2P structure. To characterize these structures, we propose several properties and corresponding quantitative methods. Finally, we conduct experiments to verify our results. © 2010 IEEE.

关键词： Structural properties

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Applications of virtual reality technology in the equipment maintenance

Applications of virtual reality technology in the equipment ...

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International Conference on Audio, Language and Image Processing

作者： Zou, Ying-Zhi Lv, Chuan Liu, Rui Beijing Institute of Strength and Environment 100076 China State Key Laboratory of Virtual Reality Technology and System Beijing 100191 China School of Reliability and Systems Engineering Beihang University 100191 China

ISBN: (纸本)9781424458653

With the rapid development of computer technology, virtual reality (VR) technology becomes more and more widely used in fields related to maintenance work. In this article, the composition and technical characteristics of VR technology is introduced, the development history and research background of VR technology is reviewed, and application status of VR system is analyzed. The application of using VR technology in equipment maintenance work, especially in the work of maintenance designing and analysis, is emphasized on in this paper, and the application prospects of VR technology are discussed. ©2010 IEEE.

关键词： Maintenance

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Integer algorithm of lapped biorthogonal transform compression method with GPU

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Beijing Hangkong Hangtian Daxue Xuebao/Journal of Beijing University of Aeronautics and Astronautics 2010年第3期36卷 368-372页

作者： Yu, Zhuo Liang, Xiaohui Ma, Shang Shen, Xukun State Key Lab of Virtual Reality Technology and Systems Beijing University of Aeronautics and Astronautics Beijing 100191 China

Compression/Decompression of huge terrain data is an important component of GC (Geometry Clipmap) method which has significant impact on rendering speed. Integral lapped biorthogonal transform (binLBT) method was used to reduce the complexity of computation by converting float point operations which spent lots of time in LBT method to integer operations and shift operations. In order to avoid the condition the data bigger than memory in graphic card, the method divided the data into some pitches which fit the memory and load one pitch each time, and then used CUDA (compute unified device architecture) to accomplish binLBT step which supports the parallel features of GPGPU (general purpose computing on graphics processing units). Experiment results show that this method based on binLBT by GPU can improve the efficiency of compression/decompression of huge terrain data and accelerate the rendering speed of GC.

关键词： Graphics processing unit

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A object surface reflectance data modeling method for isotropic opaque materials

A object surface reflectance data modeling method for isotro...

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Congress on Image and Signal Processing, CISP

作者： Ling Zou Yue Qi State key laboratory of virtual reality technology and system Beihang University Beijing China

In computer graphics research, the acquisition and modeling of 3D information of real object and the property of surface reflectance is the base of realistic rendering. This paper proposes a robust data acquisition method for surface reflectance and 3D geometric information data. Based on the accurate data acquisition and processing of the initial data, this paper implements a novel method to render realistic surface. We use the acquisition of real reflectance data to generate the BRDF sampling values of real object surface. In order to attain parametric BRDF expression, and complete the surface reflectance modeling, we use sampling values to fit Ward model. Finally, surface realistic rendering is achieved and the experiments verify the effectiveness and verisimilitude of this method.

关键词： Reflection Three dimensional displays Reflectivity Cameras Computational modeling Lighting Solid modeling

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