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Light Space Cascaded Shadow Maps Algorithm for Real Time Rendering

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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An adaptive physically-based deformation on distance fields

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Journal of Information and Computational science 2009年第6期6卷 2263-2270页

作者： Wu, Xiaoxiao Liang, Xiaohui Xu, Qidi State Key Lab. of Virtual Reality Technology School of Computer Science Beihang University Beijing 100191 China

This paper presents a novel adaptive deformation algorithm by integrating the representations of ADFs and physically based deformable models. The octree-based adaptively sampled distance fields (ADFs) are employed as the shape representation. The deformation of the ADFs is governed by the principle of physical dynamics and achieved by manipulating the scalar fields directly. A dynamic adaptive resampling scheme for ADFs is used during deformations. The physically based model of mass-spring is integrated into irregular fields for deformation. The stiffness of the non-uniform springs in the system is adaptive to spatial resolution of ADFs to avoid non-homogeneity in physics caused by the irregular structure. The results show that our physically based deformation algorithm based on the representation of ADFs outperforms regular sampled distance field based deformation algorithm in terms of time and memory efficiency, and has potential applications in physically-based interactive sculpting. © 2009 Binary Information Press.

关键词： Deformation

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A point models simplification based on energy and screen resolution for mobile devices

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Journal of Information and Computational science 2009年第5期6卷 1945-1952页

作者： He, Zhiying Liang, Xiaohui Duan, Wei State Key Lab. of Virtual Reality Technology and Systems School of Computer Science and Engineering Beihang University Beijing 100191 China

Mobile devices have two characteristics that clearly different from the conventional PC systems: low resolution and limited energy. Traditional simplification algorithm computes the error in the object space, which is pure geometry simplification. They do not consider the screen resolution of display terminal. In this paper, we present a novel point models simplification based on energy and screen resolution for mobile devices. The approach calculates the error based on the ultimate display effect, which means it could from the visual effect to determine which part should be simplified first. In addition, we consider the trade-off between visual quality and energy consumption. Energy is used to control the simplification level. Finally, we apply the method to a point models simplification which is based on MLS and splat, and then render the result points on mobile devices. © 2009 Binary Information Press.

关键词： Energy utilization

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A component-based aircraft instrument rapid modeling tool

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Journal of Zhejiang University-science C(computers and Electronics) 2010年第11期11卷 911-918页

作者： Fang-wen LI Xu-kun SHEN State Key Lab of Virtual Reality Technology and Systems School of Computer Science Beihang University Beijing 100191 China

Component-based software reuse and development is considered to be the best way to improve the efficiency and quality of *** meet the demands of aircraft instrument exhibition in an aviation virtual library,we present a modeling and simulation tool for cockpit instruments on component methods,achieving display functionality and providing a visual interaction platform in the aviation virtual *** the rapid model construction and reuse of virtual library resources,we classify entities in the cockpit into several categories by their behavior,and design a template for each category to describe its *** efficiently reduces the modeling cycle,and thus largely helps users to take advantage of the library resource.

关键词： Components Rapid modeling Simulation

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TACS: A transparent application bandwidth management system

TACS: A transparent application bandwidth management system

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IEEE 9th International Conference on computer and Information technology, CIT 2009

作者： Chen, Xianqin Long, Xiang Gao, Xiaopeng Ma, Junjie State Key Lab. of Virtual Reality Technology and System School of Computer Science and Technology Beijing University of Aeronautics and Astronautics Beijing 100191 China

ISBN: (纸本)9780769538365

With the rapid advance of computer and network technology, more and more applications are deployed in the customer-side network. These applications require different quality of service (QoS), but have to share a few bandwidth limited internet connections. Owing to the IP network's best-effort delivery mechanism, the QoS requirements are hard to be satisfied. There have been plenty of QoS solutions in research and industry areas, however, few of them are easy to understand or to deploy. Therefore, we provide a solution, based on a simple and clear model, has the ability of transparently deployed at the inner side of customer's gateway device and controlled in the application-oriented way. We also introduce a straightforward QoS policy definition language to allow user to create QoS rules for various applications. We conduct the evaluation of our proto type system running upon mid-end industrial personal computer under both the lab.testbed and the practical network. In the lab.test, our system achieves 200Mbps throughput, in the practical field test, our system successfully manages a 100Mbps internet link for over 3000 active users. © 2009 IEEE.

关键词： Quality of service

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Motion choreographing based on kinetic energy with accelerometer signal

Motion choreographing based on kinetic energy with accelerom...

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2010 International Conference on Multimedia technology, ICMT 2010

作者： Liu, Yubo Liang, Xiaohui He, Zhiying State Key Lab. of Virtual Reality Technology School of Computer Science Beihang University Beijing China

ISBN: (纸本)9781424478743

Motion choreographing is extremely important nowadays. To provide an intuitive control interface and improve the end-user's experience, low-cost accelerometer, which serving as creating and choreographing character animation based on the performers' movements, attracts more and more researchers. This paper proposes a new feature vector using kinetic energy, which can be calculated from acceleration directly. Our method gives the feature vector more accurate physical significance and improves the recognition rate. Furthermore, post-processing for signal refinement can also benefit from it. We build a prototype of motion recognition system to verify our method. Experiments show that the proposed method leads to a higher recognition rate comparing to typical methods on a database of 48 pre-trained signal data with 8 different categories. ©2010 IEEE.

关键词： Kinetic energy

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A multi-metric QoS routing method for ad hoc network

A multi-metric QoS routing method for ad hoc network

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4th International Conference on Mobile Ad-hoc and Sensor Networks, MSN 2008

作者： Wei, Wu Cao, Jing State Key Lab. of Virtual Reality Technology and Systems School of Computer Science Beihang University Beijing China

ISBN: (纸本)9780769534572

A multi-metric QoS Routing Protocol (MQOLSR) is proposed in this paper, which providing different QoS for different applications flow in an ad hoc network. The protocol, which integrates QoS measurement and packet forwarding, expands the topology discovery and routing computing mechanism of the OLSR protocol. It can provide different routing and forwarding service according to different application flow. The experimental results show that the MQOLSR protocol improves the network performance. Compared to the traditional OLSR protocol, the proposed routing protocol increases network throughput by 31.8% and reduces delay jitter when transmitting IPTV, while its routing overhead and routing discovery time are within an acceptable range. © 2008 IEEE.

关键词： Internet protocols

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Clothed and naked human shapes estimation from a single image

Clothed and naked human shapes estimation from a single imag...

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1st International Conference on Computational Visual Media, CVM 2012

作者： Guo, Yu Chen, Xiaowu Zhou, Bin Zhao, Qinping State Key Lab. of Virtual Reality Technology and Systems School of Computer Science and Engineering Beihang University Beijing China

ISBN: (纸本)9783642342622

This paper presents a novel method to simultaneously estimate the clothed and naked 3D shapes of a person. The method needs only a single photograph of a person wearing clothing. Firstly, we learn a deformable model of human clothed body shapes from a database. Then, given an input image, the deformable model is initialized with a few user-specified 2D joints and contours of the person. And the correspondence between 3D shape and 2D contours is established automatically. Finally, we optimize the parameters of the deformable model in an iterative way, and then obtain the clothed and naked 3D shapes of the person simultaneously. The experimental results on real images demonstrate the effectiveness of our method. © 2012 Springer-Verlag.

关键词： Iterative methods

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GPU accelerating for rapid multi-core cache simulation

GPU accelerating for rapid multi-core cache simulation

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25th IEEE International Parallel and Distributed Processing Symposium, Workshops and Phd Forum, IPDPSW 2011

作者： Han, Wan Xiang, Long Gao, Xiaopeng Yi, Li State Key Laboratory of Virtual Reality Technology and System School of Computer Science and Engineering Beihang University Beijing China

ISBN: (纸本)9780769543857

To find the best memory system for emerging workloads, traces are obtained during application's execution, then caches with different configurations are simulated using these traces. Since program traces can be several gigabytes, simulation of cache performance is a time consuming process. Compute unified device architecture (CUDA) is a software development platform which enables programmers to accelerate the general-purpose applications on the graphics processing unit (GPU). This paper presents a real time multi-core cache simulator, which was built based on the Pin tool to get the memory reference;and fast method for multi-core cache simulation using the CUDA-enabled GPU. The proposed method is accelerated by the following techniques: execution parallelism exploration;memory latency hiding;a novel trace compression methodology. We describe how these techniques can be incorporated into CUDA code. Experimental results show that the hybrid parallel method of time-partitioning combines with set-partitioning presented here is 11.10× speedup compared to the CPU serial simulation algorithm. The present simulator can characterize cache performance of single-threaded or multi-threaded workloads at the speeds of 6-15 MIPS. It can simulates 6 cache configurations within one single pass at this speeds compared to CMP$im, which can only simulate one cache configuration each simulation pass at the speeds of 4-10 MIPS. © 2011 IEEE.

关键词： Graphics processing unit

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Using GPU to accelerate a pin-based multi-level cache simulator 10

Using GPU to accelerate a pin-based multi-level cache simula...

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Proceedings of the 2010 Spring Simulation Multiconference

作者： Han, Wan Gao, Xiaopeng Long, Xiang Chen, Xianqin State Key Laboratory of Virtual Reality Technology and System School of Computer Science and Engineering Beihang University Beijing China

ISBN: (纸本)9781450300698

Trace-driven simulation methodology is the most widely used method to evaluate the design of future computer memory architecture. Since this methodology demands large amounts of storage and computer time, there is a growing need for simulation methodologies to determine the memory system requirements of emerging workloads in a reasonable amount of time. Several techniques have been proposed to reduce the space that store memory reference and improve the performance of sequential trace-driven simulation. This paper presents the use of binary instrumentation as the memory reference generator and parallel simulation technique that based on the generic graphics processing unit (GPU). One way to achieve fast parallel simulation is to simulate the independent sets of a cache concurrently on different compute resource, but results show that this method is not efficient because of a high correlation of the activity between different sets. To put parallelism to effective use, we show that a multi-configuration simulation in single pass method gains 2.44x performance improvement compared to traditional sequential algorithm. © 2010 SCS.

关键词： Graphics processing unit

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