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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

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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A NOVEL INTER CODING FRAMEWORK FOR H.264/AVC ON DSP PLATFORM

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A NOVEL INTER CODING FRAMEWORK FOR H.264/AVC ON DSP PLATFORM

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

2009 IEEE International Conference on Network Infrastructure and Digital Content（IC-NIDC 2009）

作者： Mingjing Ai Yumeng Li qinping zhao state key laboratory of virtual reality technology and systems beihang university beijing china 100191

A novel inter coding framework for H.264/AVC is proposed to reduce the computational complexity of H.264 encoder on DSP *** this paper,inter coding for one P slice is separated into five consecutive loops: Motion Estimation Loop,Transform ＆ Quantization Loop,Entropy Coding Loop,Deblocking Loop and Interpolation *** the macroblocks （MBs） within one P slice are processed together in each *** further explore memory hierarchy of DSP platforms,MB-group based algorithms are introduced in each loop to reduce frequent data transfers between external memory and internal ***,the proposed method is implemented on TMS320DM6446 platform and experimental results show that,for the video sequences with CIF （Common Intermediate Format） format,the optimized H.264 encoder can achieve the encoding speed of 24 frames per second,which fully meet the real-time requirements of the applications.

关键词： H.264/AVC inter coding DSP platform

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

作者： Shuai zhao Le Yu state key laboratory 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

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Parsing Objects at a Finer Granularity: A Survey

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Machine Intelligence Research 2024年第3期21卷 431-451页

作者： Yifan zhao Jia Li Yonghong Tian School of Computer Science Peking UniversityBeijing100871China state key laboratory of virtual reality technology and systems School of Computer Science and EngineeringBeihang UniversityBeijing100191China

Fine-grained visual parsing, including fine-grained part segmentation and fine-grained object recognition, has attracted considerable critical attention due to its importance in many real-world applications, e.g., agriculture, remote sensing, and space technologies. Predominant research efforts tackle these fine-grained sub-tasks following different paradigms, while the inherent relations between these tasks are neglected. Moreover, given most of the research remains fragmented, we conduct an in-depth study of the advanced work from a new perspective of learning the part relationship. In this perspective, we first consolidate recent research and benchmark syntheses with new taxonomies. Based on this consolidation, we revisit the universal challenges in fine-grained part segmentation and recognition tasks and propose new solutions by part relationship learning for these important challenges. Furthermore, we conclude several promising lines of research in fine-grained visual parsing for future research.

关键词： Finer granularity visual parsing part segmentation fine-grained object recognition part relationship

A survey on virtual reality

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Science in china(Series F) 2009年第3期52卷 348-400页

作者： zhao qinping state key laboratory of virtual reality technology and System Beihang University Beijing 100083 China

virtual reality （VR） is a scientific method and technology created during the exploration of the nature by human beings to understand, simulate, and better adapt and use the nature. Based on the analysis on the whole process of VR, this paper presents different categories of VR problems and a type of theoretical expression, and abstracts three kinds of scientific and technical problems in VR field. On the basis of foresaid content, this paper also studies current major research objectives, research results and development trend of VR in the aspects of VR modeling method, VR representation technology, human-machine interaction and devices, VR development suites and supporting infrastructure, as well as VR applications. Finally, several theoretical and technical problems that need to be further studied and solved are addressed.

关键词： virtual reality modeling rendering human-machine interaction development suite

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3D shape co-segmentation via sparse and low rank representations

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Science china(Information Sciences) 2018年第5期61卷 285-287页

作者： Liyuan YIN Kan GUO Bin ZHOU qinping zhao state key laboratory of virtual reality technology and systems School of Computer Science and EngineeringBeihang University

As a traditional and fundamental research area in computer graphics,3D shape segmentation has provided large support to many other 3D processing technologies.3D shape co-segmentation,which together with model sets,co-segments multiple 3D shape parts among the same category,has been attracting significant attention to fully utilize the common features of model sets.

关键词： NSE shape co-segmentation via sparse and low rank representations PSB

Haptics-equiped interactive PCI simulation for patient-specific surgery training and rehearsing

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Science china(Information Sciences) 2016年第10期59卷 233-238页

作者： Shuai LI Qing XIA Aimin HAO Hong QIN qinping zhao state key laboratory of virtual reality technology and systems Beihang University Department of Computer Science Stony Brook University

Despite the long history of medical simulations, suffering from the patient-specific heterogeneous heart physiological structure and complex intravascular procedures, it is still challenging for patient-specific percutaneous coronary intervention(PCI) surgery simulation. In this paper, we advocate a haptics-equiped interactive prototype system towards PCI surgeons training and patient-specific surgery rehearsing, which can afford trainees the opportunity to approximately experience the entire PCI procedures and customized emergency cases that might occur in common clinical settings. The full simulation covers tissue deformation, catheter and wire simulation, X-ray simulation, haptic feedback, and 3D realistic rendering, which in all give rise to the integrated physical, visual, haptic, and procedural realism. Our system can accommodate various comprehensive operations involved in PCI-related procedures, including feeding wires, releasing stents, injecting contrast medium, simulating X-ray, bleeding, etc. Moreover, our system framework is fully built upon CUDA, and thus can achieve real-time performance even on a common desktop. The high-fidelity, real-time efficiency and stableness of our system show great potentials for its practical applications in clinical training fields.

关键词： percutaneous coronary intervention(PCI) PCI surgery simulation patient-specific surgery rehearsing physically-based modeling haptics