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Image-based modeling of inhomogeneous single-scattering participating media

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Science China(Information Sciences) 2010年第6期53卷 1141-1150页

作者： HU Yong 1 , QI Yue 1 & TONg Xin 2 1 state key laboratory of virtual reality technology and systems, beihang university, beijing 100191, China 2 Microsoft Research Asia, beijing 100080, China 1. state key laboratory of virtual reality technology and systems Beihang University Beijing 100191 China2. Microsoft Research Asia Beijing 100080 China

We propose a method to reconstruct inhomogeneous single-scattering participating media, which could preserve fine high-frequency details of density *** data and the ratio of absorption coefficient to scattering coefficient are used to describe the spatial-varying density distribution and optical properties of certain participating media, and a function between the above parameters and captured pixel values is *** the problem of how to find solutions to these parameters is formulated into a nonlinear numerical optimization *** order to reduce large time overheads and numerical instability brought by simultaneously solving large numbers of voxels, we propose an initialization algorithm for enabling the assigned density values to satisfy the regularity of brightness distribution in captured images approximately as well as a progressive refinement algorithm for multi-resolution volumetric ***, we propose a parallel multi-voxel gradient computation algorithm of utilizing hardware acceleration to reduce time overheads in gradient computation for large numbers of *** results indicate that our method is well suited for reconstructing thin smoke, retaining high-frequency details from images captured from multiple viewpoints.

关键词： single-scattering participating media smoke modeling volumetric modeling image based modeling

Video motion stitching using trajectory and position similarities

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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

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

Simultaneous structure and geometry detail completion based on interactive user sketches

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Science China(Information Sciences) 2012年第5期55卷 1123-1137页

作者： YANg Shen 1,QI Yue 1 & QIN Hong 2 1 state key laboratory of virtual reality technology and systems,beihang university,beijing 100191,China 2 Department of Computer Science,state university of New York at Stony Brook,Stony Brook,New York 11794-4400,USA 1. state key laboratory of virtual reality technology and systems Beihang University Beijing 100191 China2. Department of Computer Science State University of New York at Stony Brook Stony Brook New York 11794-4400 USA

We articulate a novel approach to geometric model completion via interactive sketches in this ***,the initial incomplete model (with holes) is decomposed into a base model and a high-frequency component,which represents global rough shape and geometric details,*** then repair the base model via smooth hole-filling,and compute the geometry detail image using high frequency *** novel element of our approach is that we allow users to interactively sketch a few structural curves that span across hole regions,with a goal to repair both local geometric details and global *** the help of local parameterization,we convert detailed geometry into gradient-domain images which can propagate along user-specified *** integrating recovered gradient-domain images and base shape,we can generate a complete model that faithfully recovers both global structure and local *** salient contribution of this paper is the unified approach for user interaction,global structure,and geometry details towards high-fidelity model *** demonstrate our new approach using a number of examples that exhibit salient global structure as well as local geometry details.

关键词： model repair geometric modeling interactive sketch 3D graphics

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

Algorithm of simulation time synchronization over large-scale nodes

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Science in China(Series F) 2008年第9期51卷 1239-1255页

作者： ZHAO QinPing1,2,ZHOU Zhong1,2 & Lü Fang1,2 1 state key laboratory of virtual reality technology and systems,beihang university,beijing 100083,China 2 School of Computer Science and Engineering,beihang university,beijing 100083,China state key laboratory of virtual reality technology and systems Beihang University Beijing 100083 China School of Computer Science and Engineering Beihang University Beijing 100083 China

In distributed simulation, there is no uniform physical clock. And delay cannot be estimated because of jitter. So simulation time synchronization is essential for the event consistency among nodes. This paper investigates time synchronization algorithms over large-scale distributed nodes, analyzes LBTS （lower bound time stamp） computation model described in IEEE HLA standard, and then presents a grouped LBTS model. In fact, there is a default premise for existing algorithms that controi packets must be delivered via reliable transportation. Although, a theorem of time synchronization message＇s reliability is proposed, which proves that only those control messages that constrain time advance need reliability. It breaks out the default premise for reliability. Then multicast is introduced into the transmis- sion of control messages, and algorithm MCTS （multi-node coordination time synchronization） is proposed based on multicast. MCTS not only promotes the time advance efficiency, but also reduces the occupied network bandwidth. Experiment results demonstrate that the algorithm is better than others in both time advance speed and occupied network bandwidth. Its time advance speed is about 50 times per second when there are 1000 nodes, approximately equal to that of similar systems when there are 100 nodes.

关键词： distributed simulation time synchronization multi-node coordination LBTS multicast

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NAND FLASH Based Three-tier Fault-tolerant Storage Strategy

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NAND FLASH Based Three-tier Fault-tolerant Storage Strategy

virtual reality Based Process Integrated Simulation Platform in Refinery:virtual Refinery and Its Application

2011 13th IEEE Joint International Computer Science and Information technology Conference(JICSIT 2011)

作者： Jian Song state key laboratory of virtual reality technology and systems beihang university beijing, 100191, China Bing He state key laboratory of virtual reality technology and systems beihang university beijing, 100191, China

This paper proposes a NAND FLASH based three- tier fault-tolerant storage strategy. Based on the hardware properties of NAND FLASH, the strategy is to add corresponding strategies according to different levels, to improve the fault tolerance capacity of NAND FLASH effectively, and to provide higher security for the stored data. Designed with experimental analysis under the condition of high demand for data security in this paper, it can be seen that the strategy can provide higher fault tolerance capacity.

关键词： NAND FLASH fault-tolerant storage strategy

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China Petroleum Processing & Petrochemical technology 2011年第3期13卷 74-84页

作者： Zhou Zewei Feng Yiping Rong gang Wu Yucheng (state key laboratory of Industrial Control technology,Institute of Cyber-systems and Control,Zhejiang university,Hangzhou 310027,China) Zhejiang Univ State Key Lab Ind Control Technol Inst Cyber Syst & Control Hangzhou 310027 Zhejiang Peoples R China

With the combination between system simulation and virtual reality,we have established an integrated virtual refinery simulation platform,and analyzed the overall design and principal *** paper introduces a simulation algorithm about a refinery based on virtual reality,and explains how the algorithm can be applied to the virtual refinery integrated simulation platform in *** virtual refinery simulation platform,which consists of a three-dimensional scene system,an integrated database system and a dynamic-static simulation system,has many applications,such as dynamic-static simulation of key process unit used as process control and oil tank blending simulation for *** the visualization and human-computer interaction for acquiring production and process data,this platform can provide effective supports on staff training related with monitoring,control and operation in *** refinery can also be web published through the internet and it is helpful for the distance training and education.

关键词： virtual refinery petrochemical enterprise process integrated simulation information representation intelligent manufacturing systems

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The impulse influence function for de-centralized control

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Science China Mathematics 2004年第z1期47卷 200-221页

作者： ZHONg Wanxiestate key laboratory of Structure Analysis for Industrial Equipment, Dalian university of technology, Dalian 116023, China key laboratory of Complex systems & Intelligence Science, Chinese Academy of Sciences, beijing 100080, China (email: wxzhong@***) 1. state key laboratory of Structure Analysis for Industrial Equipment Dalian University of Technology 116023 Dalian China2. Key Laboratory of Complex Systems & Intelligence Science Chinese Academy of Sciences 100080 Beijing China

Impulse influence matrix function is introduced based on that the de-centralized control analysis is analogous to the sub-structural analysis in structural mechanics. The static sub-structural analysis is analogous to the usual de-centralized control, whereas the dynamic sub-structural analysis corresponds to the de-centralized control theory. The reciprocal symmetry for the impulse influence matrix function is proved, and is solved by the precise integration method for time invariant system, giving the results up to computer precision. Based on the impulse influence functions of subsystems, the combination of subsystems can lead to a set of integral equations and be solved numerically. Numerical example demonstrates the effectiveness of the method.

关键词： de-centralized control, subsystem, impulse influence function, precise integration.

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