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Data acquisition and simulation of natural phenomena

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Science china(Information Sciences) 2011年第4期54卷 683-716页

作者： zhao qinping {2. key laboratory of virtual reality technology and systems,beihang university,beijing 100191,china 1. state key {2. of virtual reality technology and systems Beihang University Beijing 100191 China

virtual natural phenomena obtained through mathematical-physical modeling and simulation as well as graphics emulation can meet the user’s requirements for sensory experiences to a certain extent but they can hardly have the same accurate physical consistency as real natural *** technology for data acquisition and natural phenomena simulation can enable us to obtain multi-dimensional and multi-modal data directly from real natural phenomena and,based on these real data,to establish digital models highly consistent with real natural phenomena in appearance,physics,behavior or many other aspects,thus making a virtual natural phenomenon a direct mapping of real natural *** approach is conducive to resolving problems concerning the reliability and availability of virtual *** present the technology for acquiring and simulating dada of natural phenomena is still in its initial *** paper gives a review of the related ***,we briefly introduce the basic methods and techniques concerned,then,based on the difference between the basic elements of various natural phenomena,we discuss the current studies on such natural phenomena as light,water,fire,smoke,dynamic terrain,etc.,and finally,in connection with issues in the present research and possible future direction of development,we put forth a number of theoretical and technical problems,hoping they can be resolved in the near future.

关键词： natural phenomena data acquisition simulation data driven reliability

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 {2. 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 {2. 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

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 {2. key laboratory of virtual reality technology and systems, School of Computer Science and Engineering, beihang university, beijing 100191, china 1. state key {2. 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

A Sensor-Service Collaboration Approach for Target Tracking in Wireless Camera Networks

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china Communications 2017年第7期14卷 44-56页

作者： Shuai zhao le Yu state key {2. of Networking and Switching technology Beijing University of Posts and Telecommunications china Mobile Information Security Center

Mobile target tracking is a necessary function of some emerging application domains, such as virtual reality, smart home and intelligent healthcare. However, existing portable devices for target tracking are resource intensive and high-cost. Camera tracking is an effective location tracking way for those emerging applications which can reuse the existing ubiquitous video monitoring system. This paper proposes a dynamic community-based camera collaboration(D3C) framework for target location and tracking. The contributions of D3C mainly include that(1) nonlinear perspective projection model is selected as the camera sensing model and sequential Monte Carlo is employed to predict the target location;(2. a dynamic collaboration scheme is proposed, it is based on the local community-detection theory deriving from social network analysis. The performance of proposed approach is validated by both synthetic datasets and real-world application. The experiment results show that D3C meets the versatility, real-time and fault tolerance requirements of target tracking applications.

关键词： service collaboration camera tracking community detection sequential monte carlo

Color liquid crystal grating based color holographic 3D display system with large viewing angle

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light(Science & Applications) 2024年第1期13卷 103-112页

作者： Di Wang Yi-long li Fan Chu Nan-Nan li zhao-Song li Sin-Doo lee zhong-Quan Nie Chao liu Qiong-Hua Wang School of Instrumentation and Optoelectronic Engineering Beihang UniversityBeijing 100191China state key {2. of virtual reality technology and systems Beihang UniversityBeijing 100191China Display technology Research Center Seoul National UniversityGwanak-ro 1Gwanak-guSeoul 08826Republic of Korea key lab of Advanced Transducers and Intelligent Control System Ministry of EducationTaiyuan University of TechnologyTaiyuan 030024China

Holographic 3D display is highly desirable for numerous applications ranging from medical treatments to military ***,it is challenging to simultaneously achieve large viewing angle and high-fidelity color reconstruction due to the intractable constraints of existing ***,we conceptually propose and experimentally demonstrate a simple and feasible pathway of using a well-designed color liquid crystal grating to overcome the inevitable chromatic aberration and enlarge the holographic viewing angle,thus enabling large-viewing-angle and color holographic 3D *** use of color liquid crystal grating allows performing secondary diffraction modulation on red,green and blue reproduced images simultaneously and extending the viewing angle in the holographic 3D display *** principle,a chromatic aberration-free hologram generation mechanism in combination with the color liquid crystal grating is proposed to pave the way for on such a superior holographic 3D *** proposed system shows a color viewing angle of~50.12.,which is about 7 times that of the traditional system with a single spatial light *** work presents a paradigm for achieving desirable holographic 3D display,and is expected to provide a new way for the wide application of holographic display.

关键词： holographic angle crystal

Self-adjustable hyper-graphs for video pose estimation based on spatial-temporal subspace construction

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Science china(Information Sciences) 2022年第3期65卷 260-262页

作者： Jizhou MA Shuai lI Hong QIN Aimin HAO qinping {2. state key {2. of virtual reality technology and systems Beihang University Department of Computer Science Stony Brook University

Dear editor,In recent years many supervised video pose estimation methods have achieved growing successes based on well-labeled training datasets. Nonetheless, when facing roughly-labeled training data, it still remains challenging to intrinsically encode the video contents’ spatial-temporal coherency for robust video pose *** researches aimed to directly improve and refine the existing confidence maps by combining the spatial-temporal structure models [1, 2.. li et al.

关键词： Video Pose Estimation Self-adjustable Hyper-graph Spatial-temporal Subspace Exploration Maximum Matching Subspace Operator Action Pattern

Designing planar cubic B-spline curves with monotonic curvature for curve interpolation

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Computational Visual Media 2020年第3期6卷 349-354页

作者： Aizeng Wang Chuan He Fei Hou Zhanchuan Cai Gang zhao School of Mechanical Engineering&Automation Beihang UniversityBeijing 100191China state key {2. of virtual reality technology&systems Beihang UniversityBeijing 100191China state key {2. of Computer Science Institute of SoftwareChinese Academy of SciencesBeijing 100190China university of Chinese Academy of Sciences Beijing 100049China Faculty of Information technology Macao University of Science and TechnologyMacao 999078China

Monotonic curvature plays an important role in industrial design and styling of curves with aesthetic shapes,e.g.,in automobile and aircraft design[1].Used in conventional parametric CAD/CAM systems,general B-splines are not adequate for aesthetic *** for the straight line and circle,monotonic curvature distribution,associated with pleasing shape,is very difficult to achieve.

关键词： curvature monotonic curves

Orthodontic simulation system with force feedback for training complete bracket placement procedures

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virtual reality & Intelligent Hardware 2021年第4期3卷 261-273页

作者： Fan YE luwei lIU Bin YAN Xiaohan zhao Aimin HAO state key {2. of virtual reality technology and systems Beihang UniversityBeijing 100083China Jiangsu key laboratory of Oral Diseases Nanjing Medical UniversityNanjing 210029China Department of Orthodontics School of StomatologyNanjing Medical UniversityNanjing 210029China

Background A virtual system that simulates the complete process of orthodontic bracket placement can be used for pre-clinical skill training to help students gain confidence by performing the required tasks on a virtual *** The hardware for the virtual simulation system is built using two force feedback devices to support bi-manual force feedback operation.A 3D mouse is used to adjust the position of the virtual patient.A multi-threaded computational methodology is adopted to satisfy the requirements of the frame *** computation threads mainly consist of the haptic thread running at a frequency of>1000Hz and the graphic thread at>*** graphic thread allows the graphics engine to effectively display the visual effects of biofilm removal and acid erosion through texture *** the haptic thread,the physics engine adopts the hierarchy octree collision-detection algorithm to simulate the multi-point and multi-region interaction between the tools and the virtual *** high efficiency guarantees that the time cost can be controlled within 1 *** physics engine also performs collision detection between the tools and particles,making it possible to simulate paint and removal of *** surface-contact constraints are defined in the system;this ensures that the bracket will not divorce from or embed into the tooth during the adjustment of the ***,the simulated adjustment is more realistic and *** A virtual system to simulate the complete process of orthodontic bracket bonding was *** addition to bracket bonding and adjustment,the system simulates the necessary auxiliary steps such as smearing,acid etching,and ***,the system supports personalized case *** The system provides a new method for students to practice orthodontic skills.

关键词： Orthodontic treatment Complete procedures Force feedback Simulation system

Visual object tracking- classical and contemporary approaches

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Frontiers of Computer Science 2016年第1期10卷 167-188页

作者： Ahmad AlI Abdul JAlIl Jianwei NIU Xiaoke zhao Saima RATHORE Javed AHMED Muhammad AKSAM IFTIKHAR Department of Computer and Information Sciences Pakistan Institute of Engineering & Applied Sciences Islamabad 44000 Pakistan state key {2. of virtual reality technology and systems School of Computer Science and Engineering Beihang University Beijing 100191 China Department of Electrical (Telecom) Engineering NUST Military College of Signals Islamabad 44000 Pakistan COMSATS Institute of Information technology Lahore 54000 Pakistan

Visual object tracking （VOT） is an important sub- field of computer vision. It has widespread application do- mains, and has been considered as an important part of surveillance and security system. VOA facilitates finding the position of target in image coordinates of video frames. While doing this, VOA also faces many challenges such as noise, clutter, occlusion, rapid change in object appearances, highly maneuvered （complex） object motion, illumination changes. In recent years, VOT has made significant progress due to availability of low-cost high-quality video cameras as well as fast computational resources, and many modern techniques have been proposed to handle the challenges faced by VOT. This article introduces the readers to 1） VOT and its applica- tions in other domains, 2. different issues which arise in it, 3） various classical as well as contemporary approaches for object tracking, 4） evaluation methodologies for VOT, and 5） online resources, i.e., annotated datasets and source code available for various tracking techniques.

关键词： visual object tracking computer vision imageprocessing point tracking kernel tracking silhouette track-ing