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2015 IEEE International Conference on computer and Communications(ICCC 2015)

作者： Huanian Zhan Yue Qi State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and Engineering Beihang University

this paper presents a retrieval method for the image of Chinese characters calligraphy. The precision and recall rate are main indicators to measure the quality of image retrieval algorithm. Starting from the two aspects, there are two parts in the process of image retrieve which is proposed in this paper. In this paper, carry out the retrieve with the Hu invariant moment matching algorithm, which is fast and efficient, but little of the accuracy. Then, execute trice retrieval with shape context algorithm taking the advantages of high level of accuracy and good robustness based on the result set of the first retrieval. Experiments show that the method referred in this paper is accurate and efficient.

关键词： calligraphy image retrieval moment invariants shape context matching

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Graphic and haptic simulation for transvaginal cholecystectomy training in NOTES

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Journal of Biomedical Informatics 2016年 60卷 410-421页

作者： Pan, Jun J. Ahn, Woojin Dargar, Saurabh Halic, Tansel Li, Bai C. Sankaranarayanan, Ganesh Roberts, Kurt Schwaitzberg, Steven De, Suvranu State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing China Center for Modeling Simulation and Imaging in Medicine Rensselaer Polytechnic Institute Troy United States Computer Science Department University of Central Arkansas Conway United States Gastrointestinal Surgery Yale School of Medicine Yale University New Heaven United States Department of Surgery Cambridge Health Alliance Harvard Medical School Boston United States

Background: Natural Orifice Transluminal Endoscopic Surgery (NOTES) provides an emerging surgical technique which usually needs a long learning curve for surgeons. virtual reality (VR) medical simulators with vision and haptic feedback can usually offer an efficient and cost-effective alternative without risk to the traditional training approaches. Under this motivation, we developed the first virtual reality simulator for transvaginal cholecystectomy in NOTES (VTEST™). Methods: This VR-based surgical simulator aims to simulate the hybrid NOTES of cholecystectomy. We use a 6DOF haptic device and a tracking sensor to construct the core hardware component of simulator. For software, an innovative approach based on the inner-spheres is presented to deform the organs in real time. To handle the frequent collision between soft tissue and surgical instruments, an adaptive collision detection method based on GPU is designed and implemented. To give a realistic visual performance of gallbladder fat tissue removal by cautery hook, a multi-layer hexahedral model is presented to simulate the electric dissection of fat tissue. Results: From the experimental results, trainees can operate in real time with high degree of stability and fidelity. A preliminary study was also performed to evaluate the realism and the usefulness of this hybrid NOTES simulator. Conclusions: This prototyped simulation system has been verified by surgeons through a pilot study. Some items of its visual performance and the utility were rated fairly high by the participants during testing. It exhibits the potential to improve the surgical skills of trainee and effectively shorten their learning curve. © 2016 Elsevier Inc.

关键词： virtual reality

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Transformation of Chinese Calligraphy Style Based on Feature Matrix Editing

Transformation of Chinese Calligraphy Style Based on Feature...

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International Conference on computer Science and Network technology

作者： Shi-Lei Zhang Zhao-Kai Xie Yue Qi State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and Engineering Beihang University Beijing China

Strokes of Chinese characters are extracted from a picture of calligraphy work by image processing methods. By analyzing the stroke's centerline location, width, constriction velocity and curvature, a feature matr... 详细信息

ISBN: (纸本)9781467381741

关键词： calligraphy style feature editing image processing Image processing Stroke editing image processing method matrices Chinese philosophy Chinese Chinese Chinese art Chinese script images

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Mining friendships through spatial-temporal features in mobile social networks

Mining friendships through spatial-temporal features in mobi...

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IEEE International Conference on Performance, Computing and Communications (IPCCC)

作者： Jianwei Niu Danning Wang Jie Lu State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and Engineering Beihang University Beijing China

With the rapid popularization of smartphones and tablets, there are thousands of applications based on mobile social networks. The big data from these networks provide a huge potential to shed light on the mobility patterns of users. These big data enable a deeper understanding of users' preferences and behaviors and will help us mine users' friendship in both physical and digital worlds. In this paper, we firstly divide user mobility patterns into different categories to portray the characteristics of user encounter more precisely. Then, with combining proximity data from bluetooth devices and location data from cellular towers, we introduce a set of spatial-temporal features, including the encounter entropy, which measures the probability of encounters between different mobile users. Using these spatial-temporal features, we provide a novel model to infer user friendship by analyzing the social context of users and their encounters. To address the class imbalance problem in the dataset and improve the prediction accuracy of friendship, we employ the sampling method and evaluate our model with three different classifiers. The experimental results show that our encounter entropy feature has a striking effect to infer user friendship, and our model based on these spatial-temporal features can achieve pretty good accuracy in predicting friendship over real human mobility traces without privacy-sensitive information disclosure.

关键词： Poles and towers Bluetooth Social network services Entropy Smart phones Mobile communication

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Lighting virtual objects in a single image via coarse scene understanding

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Science China(Information Sciences) 2014年第9期57卷 58-71页

作者： CHEN XiaoWu JIN Xin WANG Ke State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and EngineeringBeihang University

Achieving convincing visual consistency between virtual objects and a real scene mainly relies on the lighting effects of virtual-real composition *** problem becomes more challenging in lighting virtual objects in a single real ***,scene understanding from a single image has made great *** estimated geometry,semantic labels and intrinsic components provide mostly coarse information,and are not accurate enough to re-render the whole ***,carefully integrating the estimated coarse information can lead to an estimate of the illumination parameters of the real *** present a novel method that uses the coarse information estimated by current scene understanding technology to estimate the parameters of a ray-based illumination model to light virtual objects in a real *** key idea is to estimate the illumination via a sparse set of small 3D surfaces using normal and semantic *** coarse shading image obtained by intrinsic image decomposition is considered as the irradiance of the selected small *** virtual objects are illuminated by the estimated illumination *** results show that our method can convincingly light virtual objects in a single real image,without any pre-recorded 3D geometry,reflectance,illumination acquisition equipment or imaging information of the image.

关键词： illumination estimation lighting virtual object single image scene understanding photo editing

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Structure guided texture inpainting through multi-scale patches and global optimization for image completion

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Science China(Information Sciences) 2014年第1期57卷 25-40页

作者： CHEN XiaoWu ZHOU Bin GUO Yu XU Fang ZHAO QinPing State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and Engineering Beihang University

Automatic image completion can provide convenient editing of consumer *** image completion methods find the best patch locally and then copy it to the hole region for texture *** the best patch is fixed in size,it is hard to adapt these methods efciently either to various patterns or to content ***,salient image structures can be estimated and propagated to guide the texture inpainting process for more plausible *** paper presents a novel image completion method using structure guided texture *** do not require any interactions to achieve automatic two-stage image *** the structure completion stage,the salient structures around the hole region are detected,and then the missing structure curves are completed with Euler *** textures along the structure curves are completed through belief *** the texture inpainting stage,we propose multi-scale patches and global optimization to inpaint the remaining texture in the hole regions guided by the completed ***,with defined patch sizes,the hole region is divided into lattice patches,making it possible for multiple patch sizes to render multiscale descriptions of this image.A multi-scale graph is then built for the hole region and formulated as a posterior probability ***,using a simulated annealing based Markov chain Monte Carlo method,an inference algorithm is designed to find a global optimization solution for the posterior probability *** experiments show that our method can automatically complete the hole region and preserve plausible structure shapes of existing ones in various *** texture inpainting results are more convincing with guidance from the completed structures,and our method can guarantee and accelerate convergence of the global optimization.

关键词： image completion texture inpainting structure propagation global optimization

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VINCE: Exploiting visible light sensing for smartphone-based NFC systems

VINCE: Exploiting visible light sensing for smartphone-based...

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IEEE Annual Joint Conference: INFOCOM, IEEE computer and Communications Societies

作者： Jianwei Niu Fei Gu Ruogu Zhou Guoliang Xing Wei Xiang State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing China Department of Computer Science and Engineering Michigan State University

This paper presents VINCE - a novel visible light sensing design for smartphone-based Near Field Communication (NFC) systems. VINCE encodes information as different brightness levels of smartphone screens, while receivers capture the light signal via light sensors. In contrast to RF technologies, the direction and distance of such a Visible Light Communication (VLC) link can be easily controlled, preserving communication privacy and security. As a result, VINCE can be used in a wide range of NFC applications such as contactless payments and device pairing. We experimentally profile the impact of screen brightness levels and refresh rates of smartphones, and then use the results to guide the design of light intensity encoding scheme of VINCE. We adopt several signal processing techniques and empirically derive a model to deal with the significant variation of received light intensity caused by noises and low screen refresh rates. To improve the communication reliability, VINCE adopts a feedback-based retransmission scheme, and dynamically adjusts the number of encoding brightness levels based on the current light channel condition. We also derive an analytical model that characterizes the relation among the distance, SNR (Signal to Noise Ratio), and BER (Bit Error Rate) of VINCE. Our design and theoretical model are validated via extensive evaluations using a hardware implementation of VINCE on Android smartphones and the Arduino platform.

关键词： Brightness Receivers Sensors Encoding Decoding Signal to noise ratio

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Fast and compact dynamic data compression based on composite rigid body construction

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Science China(Information Sciences) 2014年第11期57卷 66-84页

作者： MA ZhiQiang WANG LiLi ZHANG BoNing KE Wei ZHAO QinPing State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and EngineeringBeihang University Macao Polytechnic Institute

3D dynamic datasets compression still poses two challenges. One is high time cost due to growing data and complex computation of compression algorithms. The other is low compression factor because of complex motions of dynamic scenes and unknown motion equations. In this paper, composite rigid body construction for fast and compact compression of 3D dynamic datasets is proposed to solve these two problems. It accelerates the compression with a fast rigid body decomposition based on disjoint union, and avoids serial searching, comparing and merging of the rigid body decomposition. To increase the compression factor,composite rigid body is introduced with consideration of motion consistency among rigid bodies at different time periods. The results of the experiments show that our algorithm compresses dynamic datasets quickly and achieves a high compression factor.

关键词： time-varying datasets dynamic datasets compression rigid body decomposition disjoint union composite rigid body construction

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CLMRS: Designing Cross-LAN Media Resources Sharing Based on DLNA

CLMRS: Designing Cross-LAN Media Resources Sharing Based on ...

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IEEE International Conference on Cyber Security and Cloud Computing (CSCloud)

作者： Fei Gu Jianwei Niu Zhenxue He Meikang Qiu Cuijiao Fu State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing China Department of Computer Scieqnce Pace University New York America

ISBN: (纸本)9781467393010

Digital Living Network Alliance (DLNA) puts forward an interoperable architecture of home network equipment to implement the simple and seamless interoperability between household appliances, mobile devices and computers, so as to enhance and enrich users' experience. Because DLNA is designed to implement the sharing of multimedia resources between devices in a family environment, it does not support cross-LAN accessing. Currently, the cross-network cooperative work between smart devices has become a hot issue. To overcome this problem, this paper presents CLMRS - a cross-LAN accessing solution of C/S architecture based on DLNA technology. CLMRS can be used to implement cross-network media resources sharing by designing DLNA gateway/router of applicaion-level. We use DLNA gateway as a agent of LAN which is designed to transpond communication messages and to redirect address. To achieve cross-LAN media resources sharing, CLMRS adapts DLNA router as a transfer server to transpond communication data and to manage users access right. We also optimize the transmission path of media Steam to reduce the pressure of DLNA router. In order to protect user privacy, CLMRS sets a family account to limit the access right and proposes an efficient and secure authentication mechanism with anonymity. Our design and theoretical model are validated via implementing an instance of DLNA cross-network communication. Experimental results show that the approach is practical and can protect user privacy effectively.

关键词： Logic gates Media Home automation IP networks virtual private networks Local area networks Servers

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WicLoc: An Indoor Localization System based on WiFi Fingerprints and Crowdsourcing

WicLoc: An Indoor Localization System based on WiFi Fingerpr...

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IEEE International Conference on Communications

作者： Jianwei Niu Bowei Wang Long Cheng Joel J. P. C. Rodrigues State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and Engineering Beihang University Instituto de Telecomunicacoes University of Beira Interior

ISBN: (纸本)9781467364300

WiFi fingerprint-based indoor localization techniques have been proposed and widely used in recent years. Most solutions need a site survey to collect fingerprints from interested locations to construct the fingerprint database. However, the site survey is labor-intensive and time-consuming. To overcome this shortcoming, we record user motions as well as WiFi signals without the active participation of the users to construct the fingerprint database, in place of the previous site survey. In this paper, we develop an indoor localization system called WicLoc, which is based on WiFi fingerprinting and crowdsourcing. We design a fingerprint model to form fingerprints of each location of interest after fingerprint collection. We propose a weighted KNN (K-Nearest Neighbor) algorithm to assign different weights to APs and achieve room-level localization. To obtain the absolute coordinate of users, we design a novel MDS (Multi-Dimensional Scaling) algorithm called MDS-C (Multi-Dimensional Scaling with Calibrations) to calculate coordinates of interested locations in the corridor and rooms, where anchor points are used to calibrate absolute coordinates of users. Experimental results show that our system can achieve a competitive localization accuracy compared with state-of-the-art WiFi fingerprint-based methods while avoiding the labor-intensive site survey.

关键词： Indoor localization WiFi Fingerprints Crowd-sourcing K-Nearest Neighbor Multi-Dimensional Scaling

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