检索结果-内蒙古大学图书馆

A geometry-bias-based photon map reconstruction and illumination estimation

International Journal of Advancements in Computing technology 2012年第17期4卷 560-570页

作者： Cai, Peng Kong, Dehui Yin, Baocai Zhang, Yong Beijing Key Laboratory of Multimedia and Intelligent Software Technology College Of Computer Science and Technology Beijing University Of Technology Beijing China

Photon mapping can efficiently render high-quality photorealistic images with full global illumination. It stores many photons in photon map for improving estimated qualities of complex illumination, which leads to high memory overhead and long computation time. The usual methods of illumination estimation of photon map are easy to produce illumination error due to geometry bias. We give two effective solutions for these existing problems. On the one hand, this paper presents a geometry-bias-based reconstruction of photon map. Based on the number of photons and the curvature variation of surface in every non-empty grid, we take a fraction of photons in grids to reconstruct global photon map. The method has low computation cost and keeps view-independence of photon map. Compared with the non-reconstructed photon map with the same number of photons, the reconstructed photon map has far better effect of illumination estimation, and can effectively reduce all kinds of geometrically incurred illumination errors. On the other, we propose a geometry-bias-based illumination estimation of photon map. Based on true area of illumination estimation, which is intersection area between bounding sphere of photons estimating illumination and almost coplanar triangle meshes including these photons, the estimated illumination effect can be largely improved by reduction of geometry bias of illumination estimation.

关键词： Photons

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Spatially adaptive threshold for image denoisng based on nonsubsampled contourlet transform

Spatially adaptive threshold for image denoisng based on non...

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2012 3rd IEEE International Conference on Network Infrastructure and Digital Content, IC-NIDC 2012

作者： Sun, Xiangda Du, Junping Zhou, Yipeng Beijing Key Laboratory of Intelligent Telecommunications Software and Multimedia School of Computer Science Beijing University of Posts and Telecommunications Beijing 100876 China School of Computer and Information Engineering Beijing Technology and Business University Beijing 102401 China

ISBN: (纸本)9781467322027

In recent years, the threshold for removing noise based on wavelet transform has been very widely used because of its effectiveness and simplicity. Thus, there has been threshold based on a variety of frequency-domain transform. During the process of denoising, due to the differentiation of transform coefficients generated by noise and edge information, a good threshold for denoising can make a significant impact on the image quality. In currently existing threshold, spatially adaptive threshold based on Context-Modeling is proposed because of having considered neighboring coefficients so that it can adjust to coefficient characteristics. In this paper the improved spatially adaptive threshold method is applied to the nonsubsampled contourlet transform. Experimental results show that the method yields superior image quality and higher PSNR. © 2012 IEEE.

关键词： Image quality

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Passive diagnosis for WSNs using data traces

Passive diagnosis for WSNs using data traces

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8th IEEE International Conference on Distributed Computing in Sensor Systems, DCOSS 2012

作者： Nie, Jiangwu Ma, Huadong Mo, Lufeng Beijing Key Laboratory of Intelligent Telecommunications Software and Multimedia Beijing University of Posts and Telecommunications China College of Information Engineering Zhejiang A and F University China

ISBN: (纸本)9780769547077

Diagnosis for wireless sensor networks is difficult,due to the limited resources and the ad hoc manner of *** existing approaches mainly focus on collecting diagnosismetrics, which bring heavy communication overhead to thenetwork. We present a new model called DSD for networkdiagnosis which deduce the root causes for failures using thesensing data traces. We discover that the characteristics of thesensing data reflect the network status in some way, accordingto considerable experiments in the GreenOrbs project. We minethe relationships between the sensing data and the failures in thesensor networks, and record them in a failure knowledge *** this diagnosis mechanism, we deduce the root causeof the failures without adding any additional network ***, the failure knowledge library can be used to improvethe efficiency of diagnosis. We analyze the three months sensingdata from the GreenOrbs project, and experimental results showthat the proposed scheme can improve the diagnosis performancewith low energy cost. © 2012 IEEE.

关键词： Wireless sensor networks

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Spread of behavior in unstructured peer-to-peer networks

Spread of behavior in unstructured peer-to-peer networks

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2012 International Conference on computer Science and Service System, CSSS 2012

作者： Ma, Wenming Zhang, Yujie Meng, Xiangwu Beijing Key Laboratory of Intelligent Telecommunications Software and Multimedia Beijing University of Posts and Telecommunications Beijing 100876 China School of Computer Beijing University of Posts and Telecommunications Beijing 100876 China

ISBN: (纸本)9780769547190

Many researchers think that networks with small world effect are always more effective for spread of behavior, but a fewer studies indicated that the behavior spread farther and faster in clustered-lattice networks than in other networks. In this paper, we analyzed the spread of behavior in unstructured peer-to-peer networks with three different topologies. The experimental results show that to get a good spread effect, each kind of network should satisfy several boundary conditions, and peer churn rate is not a key factor impacting on the speed of the spread of behavior. © 2012 IEEE.

关键词： Peer to peer networks

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A Geometry-Bias-Based Reconstruction of Global Photon Maps

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Procedia Engineering 2012年 29卷 824-831页

作者： Peng Cai Dehui Kong Baocai Yin Yong Zhang Beijing Key Laboratory of Multimedia and Intelligent Software Technology College Of Computer Science and Technology Beijing University Of Technology Beijing 100124 P.R. China

Photon mapping can efficiently render high-quality photorealistic images with full global illumination. It stores many photons in photon map for improving reconstruction qualities of complex illumination, which leads to high memory overhead and long reconstruction time. This paper presents a geometry-biasbased reconstruction of global photon maps. We divide the bounding box of photons into a number of grids. Based on the number of photons and the curvature variation of surface in every non-empty grid, we take a fraction of photons in grid to reconstruct global photon map, and ensure conservation of total energy of photons in grid before and after reconstruction. Our method has low computation cost and keeps view-independence of photon map. The experiments show that the differences of reconstructed illumination effects between two photon maps are very small even if the photon number of photon map before reconstruction is 20 times the one after reconstruction. Compared with the non-reconstructed photon map with the same number of photons, the reconstructed photon map has far better reconstructed illumination effect, and can effectively reduce illumination error due to all kinds of geometry biases.

关键词： global photon map reconstruction geometry bias

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Face Recognition Based on Sparsity Preserving Projections and Gabor Transform

Face Recognition Based on Sparsity Preserving Projections an...

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2012年管理与服务科学国际会议(MASS 2012)

作者： Xinwu Yang Xiaojun Xu Chunnian Liu Beijing Key Laboratory of Multimedia and Intelligent Software Technology College of Computer Science and Technology Beijing University of Technology

Sparsity preserving projections (SPP) rooted in compressive sensing has already been successfully applied in face recognition. But we can only get good recognition results on a large dataset by SPP. It is difficult to get similar high recognition rate on a small dataset. However, in many practical applications, we have to use SPP on small-scale datasets. In order to obtain a better recognition rate on a small number of samples, we proposed a new face recognition method integrating Gabor transform and SPP (GTSPP). In the new method, we firstly carry out Gabor transform on every face sample at a combination of different frequency and direction. Then we constitute a new dataset that consists directly of the coefficients of Gabor transform at each combination of frequency and direction. The new dataset is larger than the original dataset. Finally, SPP is used to recognize human identity on the new larger dataset. We conduct experiments on publicly available dataset (Yale and AR) to verify the feasibility and effectiveness of the proposed method and explain why it has a higher recognition rate than SPP.

关键词： Gabor transform sparsity preserving projections compressive sensing face recognition

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3D Face Regulation Based on Surface Deformation

3D Face Regulation Based on Surface Deformation

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International Conference on Wireless Communications, Networking and Mobile Computing (WiCom)

作者： Yun Ge Baicai Yin Yanfeng Sun Hengliang Tang Beijing Key Laboratory of Multimedia and Intelligent Software Technology College of Computer Science and Technology Beijing University of Technology Beijing China

3D face database is an important data platform for model training, algorithm design. Especially for these researches based on statistical learning method, the algorithm performance has a great dependency on training sample set. Subject to the constraint of data acquisition equipment the data structure of current 3D face samples are different. It is incontinent to use these samples without regulation. To solve this problem, this paper presents an regulating method for existing 3D databases based on surface deformation. The experiment results show that the proposed method has good performance on face regulation.

关键词： Face Databases Iterative closest point algorithm Transforms Shape Educational institutions Solid modeling

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OF-NEDL: An OpenFlow networking experiment description language based on XML

OF-NEDL: An OpenFlow networking experiment description langu...

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2012 International Conference on Web Information Systems and Mining, WISM 2012

作者： Liang, Junxue Lin, Zhaowen Ma, Yan Research Institute of Network Technology Beijing University of Posts and Telecommunications 100876 Beijing China Beijing Key Laboratory of Intelligent Telecommunications Software and Multimedia Beijing University of Posts and Telecommunications 100876 Beijing China

ISBN: (纸本)9783642334689

OpenFlow is a promising future Internet enabling technology and has been widely used in the network research community to evaluate new network protocols, applications, and architectures. However, most of these research activities or experimentations are lack of a uniformed description so can be repeated by other researchers. In this paper, we investigate the general model of an OpenFlow networking experiment and propose a language, OF-NEDL, which aspires to bridge this gap by providing a simple, comprehensive and extensible language for describing OpenFlow networking experiment. OF-NEDL allows the researcher to write a script to control every aspect of an OpenFlow networking experiment, including the hierarchical network topology description, the OpenFlow network devices configuration, the experiment software deployment, the experiment process control, monitoring and output collection. Our preliminary usage scenario shows that it has the ability to describe simple but extensible networking experiment, and we expect to refine considerably its design to make it more practical in the future work. © Springer-Verlag Berlin Heidelberg 2012.

关键词： XML

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Realistic mesh compression based on geometry image

Realistic mesh compression based on geometry image

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Picture Coding Symposium, PCS

作者： Yunhui Shi Bo Wen Wenpeng Ding Na Qi Baocai Yin Beijing Key Laboratory of Multimedia and Intelligent Software Technology College of Computer Science and TechnologyBeijing University of Technology Beijing China

In order to show the realistic 3D mesh in geometry image-based 3D mesh compression, in addition to coding geometry image, normal-map image is usually required to code. But normal-map image are difficult to compress because it captures more details of the original mesh, and it has less spatial correlation between pixels than geometry image. This paper proposes a novel coding framework to solve this problem, we effectively predict the normal-map image based on the correlation between geometry image and normal-map image, and we also utilize the strong correlation among three components of normal-map image to improve the predicting accuracy. In this framework we only need to code geometry image and residual image which generated from normal-map image and its prediction. Experimental results show that comparing with the method which coding geometry image and normal-map image using JPEG2000 directly, our coding framework not only improves the coding efficiency of geometry images and normal-map images, but also enhances the realistic effect of 3D mesh significantly.

关键词： Geometry Image coding Three dimensional displays Image reconstruction Correlation Encoding Vectors

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Rule-based procedural modeling of buildings

Rule-based procedural modeling of buildings

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IEEE International Conference on computer Science and Automation Engineering (CSAE)

作者： Jiazhen Li Yong Zhang Dehui Kong Beijing Municipal Key Laboratory of Multimedia and Intelligent Software Technology College of Computer Science Beijing University of Technology Beijing China

The demand of virtual 3D models is growing rapidly with the development of city informatization and digitalization. Buildings are essential objects of virtual city. Over the years, researchers have made considerable progress towards developing efficient techniques for generating 3D buildings, however, procedural modeling is still a challenging task because of limitation of data sources and reality requirement restraints. To overcome this problem, this paper introduces a procedural method based on rule sets according to certain criterion available to common building all over the world. We describe the modeling processing based on two-dimension GIS data and digital image. The experiments showed that the presented approach is an automatic and effective method for modeling mass buildings.

关键词： Computational modeling Solid modeling Cities and towns Geometry Data models Floors

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