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22nd Pacific Conference on Computer Graphics and Applications, PG 2014

作者： Gu, Minjie Hu, Shanfeng Wang, Xiaochuan Liang, Xiaohui Shen, Xukun Qin, Aihong State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing China Zhejiang Institute of Media and Communications Hangzhou China

ISBN: (纸本)9783905674736

Current compression methods compress depth images by incorporating 2D features, which leads to a loss of the detail of the original 3D object in the recovered depth image. The main idea of this paper is to augment 2D features with 3D geometric information to preserve important regions of the depth image. Mesh saliency is used to represent the important regions of the 3D objects, and discontinuity edges are extracted to indicate the important regions of the depth image. We use mesh saliency to guide the adaptive random sampling to generate a random pixel sample of the depth image and then, combine this sample with the depth discontinuity edge to build the sparse depth representation. During the depth reconstruction, the depth image is recovered by using an up- and down-sampling schema with Gaussian bilateral filtering. The effectiveness of the proposed method is validated through 3D image warping applications. The visual and quantitative results show a significant improvement of the synthetic image quality compared with state-of-the-art depth compression methods. © The Eurographics Association 2014.

关键词： Image enhancement

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Dynamic modeling and control simulation of a modified delta manipulator

Dynamic modeling and control simulation of a modified delta ...

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2015 IEEE International Conference on Information and Automation, ICIA 2015 - In conjunction with 2015 IEEE International Conference on Automation and Logistics

作者： Hao, Jianlong Xie, Xiaoliang Bian, Guibin Feng, Zhenqiu Gao, Zhanjie Hou, Zengguang Yu, Hongnian Vladareanu, Luige State Key Laboratory of Management and Control for Complex Systems Institute of Automation Chinese Academy of Sciences Beijing100190 China Faculty of Science and Technology Bournemouth University Poole DorsetBH12 5BB United Kingdom Robotics and Mechatronics Department Institute of Solid Mechanics Romanian Academy 15 C-tin Mille Street Bucharest 1 Romania

ISBN: (纸本)9781467391047

The delta parallel mechanism has proven to be a very successful parallel robot design and a number of variants have been proposed in the literature. Taking advantage of its simple construction and the intrinsic features such as high stiffness and accuracy, delta robots play an important role both in the fields of industrial robots and academical fields. In this paper, dynamic modeling and control simulation of a cable-driven modified delta manipulator for haptic interface are discussed. For the parallel mechanism is highly coupled and nonlinear, the dynamic model is of great importance for model-based controller to achieve a satisfactory performance. Based on the principle of virtual work, the dynamic equations of this manipulator are established. The proportional-derivative (PD) computed torque control scheme is proposed for trajectory tracking. With the help of the virtual prototype builded in ADAMS software and used in MATLAB software, the co-simulation is accomplished and the results validate the performance of the controller proposed in this paper. © 2015 IEEE.

关键词： Manipulators

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Depth of field rendering via adaptive recursive filtering 14

Depth of field rendering via adaptive recursive filtering

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SIGGRAPH Asia 2014 Technical Briefs, SA 2014

作者： Xu, Shibiao Mei, Xing Dong, Weiming Sun, Xun Shen, Xukun Zhang, Xiaopeng NLPR Institute of Automation Chinese Academy of Sciences Beijing China State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing China Baidu Institute of Deep Learning Beijing China

ISBN: (纸本)9781450328951

We present a new post-processing method for rendering high-quality depth-of-field effects in real time. Our method is based on a recursive filtering process, which adaptively smooths the image frame with local depth and circle of confusion information. Unlike previous post-filtering approaches that rely on various convolution kernels, the behavior of our filter is controlled by a weighting function defined between two neighboring pixels. By properly designing this weighting function, our method produces spatially-varying smoothed results, correctly handles the boundaries between in-focus and out-of-focus objects, and avoids rendering artifacts such as intensity leakage and blurring discontinuity. Additionally, our method works on the full frame without resorting to image pyramids. Our algorithms runs efficiently on graphics hardware. We demonstrate the effectiveness of the proposed method with several complex scenes.

关键词： Information filtering

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An HLA/RTI Architecture Based on Periodic and Aperiodic Tasks Scheduling for Real-time Improvement

An HLA/RTI Architecture Based on Periodic and Aperiodic Task...

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2014中国制导、导航与控制学术会议

作者： Shutian Liu Shuling Dai State Key Laboratory of Virtual Reality Technology and Systems Beihang UniversityBeijing100191 China Flight Theory Department Naval Aviation InstituteHuludaoLiaoning125001 China State Key Laboratory of Virtual Reality Technology and SystemsBeihang UniversityBeijing100191 China

ISBN: (纸本)9781479946983

The work takes place in the context of the HLA (High Level Architecture) standard and its application for pursuit of real-time *** of precedence constraint of correlated tasks between federates,it is hard to provide predictable response for all tasks,and it is also difficult to ensure the real-time performance of all tasks,especially aperiodic *** the architecture we proposed D-EDF (Double Earliest Deadline First) strategy to schedule overall periodic and aperiodic tasks inside a federate from the point view of task scheduling *** policy not only discards some redundant data to ensure the periodic tasks completed effectively before their deadlines,but also schedules aperiodic ones running regularly to improve their real-time responding *** simulation results show that the policy can effectively handle the tasks with precedence constraints and consequently improve the real-time performance of RTI.

关键词： digital simulation scheduling software performance evaluation D-EDF strategy HLA architecture RTI architecture aperiodic tasks scheduling double earliest deadline first high level architecture Conferences Navigation

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Edge-preserving image decomposition based on saliency map

Edge-preserving image decomposition based on saliency map

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Congress on Image and Signal Processing, CISP

作者： Ce Feng Shuling Dai Yongjia Zhao Shutian Liu State Key Laboratory of Virtual Reality Technology and Systems Beihang University Beijing China Flight Theory Department Naval Aviation Institute Huludao China

ISBN: (纸本)9781479958368

A novel edge-preserving image decomposition based on saliency map is proposed to avoid halo phenomena in traditional image decompositions. Our method uses feature of saliency map that emphasizes salient edges in image to determine whether a region should be retained or processed, and then blur the image adaptively according to the local saliency average gradient. Experiments show that the proposed decomposition performs well in smoothing and enhancement. We compare our results with the guided filter and bilateral filter, and demonstrate a variety of applications including HDR and multi-scale enhancement.

关键词： Image edge detection Filtering algorithms Smoothing methods Filtering theory Noise Image decomposition Educational institutions

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Sparse Dictionary Learning for Edit Propagation of High-resolution Images

Sparse Dictionary Learning for Edit Propagation of High-reso...

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IEEE Conference on Computer Vision and Pattern Recognition

作者： Xiaowu Chen Dongqing Zou Jianwei Li Xiaochun Cao Qinping Zhao Hao Zhang State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and Engineering Beihang University Institute of Information Engineering Chinese Academy of Sciences Simon Fraser University

ISBN: (纸本)9781479951192

We introduce a method of sparse dictionary learning for edit propagation of high-resolution images or video. Previous approaches for edit propagation typically employ a global optimization over the whole set of image pixels, incurring a prohibitively high memory and time consumption for high-resolution images. Rather than propagating an edit pixel by pixel, we follow the principle of sparse representation to obtain a compact set of representative samples (or features) and perform edit propagation on the samples instead. The sparse set of samples provides an intrinsic basis for an input image, and the coding coefficients capture the linear relationship between all pixels and the samples. The representative set of samples is then optimized by a novel scheme which maximizes the KL-divergence between each sample pair to remove redundant samples. We show several applications of sparsity-based edit propagation including video recoloring, theme editing, and seamless cloning, operating on both color and texture features. We demonstrate that with a sample-to-pixel ratio in the order of 0.01%, signifying a significant reduction on memory consumption, our method still maintains a high-degree of visual fidelity.

关键词： Image color analysis Dictionaries Equations Mathematical model Cloning Encoding Optimization

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Transparency enhanced multirate wave variable control scheme with energy reusage

Transparency enhanced multirate wave variable control scheme...

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IEEE International Conference on robotics and Biomimetics

作者： Yong Liu Xulong Zhang Wusheng Chou The State Key Lab of Virtual Reality Technology and Systems of China Beihang University Beijing China The Robotic Research Institute Beihang University Beijing China

ISBN: (纸本)9781479973989

This paper presents a newly designed control scheme for haptic interaction with uniform sample rate virtual environment. In most practical application in haptic interaction, we lack the knowledge about the model of the sampling rate. Unfortunately, by using the conventional wave variable method, the impedance parameter should adjust accordingly to guarantee the passivity of the interaction. Considering the inconvenient of the wave variable method, a novel scheme, named multirate wave transformation with energy reusage, is introduced. The proposed control scheme re-harvests the energy leakage caused by sampling rate by an energy observer, and an energy reservoir is formed to accumulate the re-harvested energy. Then, an energy regulator reuses the energy to passify the haptic interaction. Furthermore, we also demonstrated by analysis that the proposed control scheme can achieve a better interactive transparency by comparison with the traditional wave variable method. Finally, the effectiveness and performance of the proposed control scheme are validated with a haptic rendering experimental platform.

关键词： Haptic interfaces virtual environments Force Impedance Reservoirs Regulators Rendering (computer graphics)

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Dynamic characteristic analysis of whole machine tools based on Kriging model

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Journal of Central South University 2013年第11期20卷 3094-3102页

作者：高相胜张以都郜浩冬张洪伟 State Key Laboratory of Virtual Reality Technology and Systems (Beihang University) School of Mechanical Engineering and Automation Beihang University School of Mechanical Engineering Beijing Institute of Petrochemical Technology

In order to study the variation of machine tools’dynamic characteristics in the manufacturing space,a Kriging approximate model is *** element method(FEM)is employed on the platform of ANSYS to establish finite element(FE)model with the dynamic characteristic of combined interface for a milling machine,which is newly designed for producing aero engine blades by a certain enterprise group in *** stiffness and damping of combined interfaces are adjusted by using adaptive simulated annealing algorithm with the optimizing software of iSIGHT in the process of FE model update according to experimental modal analysis(EMA)*** Kriging approximate model is established according to the finite element analysis results utilizing orthogonal design samples by taking into account of the range of configuration *** the basis of the Kriging approximate model,the response surfaces between key response parameter and configuration parameters are *** results indicate that configuration parameters have great effects on dynamic characteristics of machine tools,and the Kriging approximate model is an effective and rapid method for estimating dynamic characteristics of machine tools in the manufacturing space.

关键词： machine tool dynamic characteristic interface configuration Kriging model

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A practical analytic model for the radiosity of translucent scenes 13

A practical analytic model for the radiosity of translucent ...

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17th ACM SIGGRAPH Symposium on Interactive 3D Graphics and Games, I3D 2013

作者： Sheng, Yu Shi, Yulong Wang, Lili Narasimhan, Srinivasa G. Robotics Institute Carnegie Mellon University United States State Key Laboratory of Virtual Reality Technology and Systems Beihang University China

ISBN: (纸本)9781450319560

Light propagation in scenes with translucent objects is hard to model efficiently for interactive applications. The inter-reflections between objects and their environments and the subsurface scattering through the materials intertwine to produce visual effects like color bleeding, light glows and soft shading. Monte-Carlo based approaches have demonstrated impressive results but are computationally expensive, and faster approaches model either only inter-reflections or only subsurface scattering. In this paper, we present a simple analytic model that combines diffuse inter-reflections and isotropic subsurface scattering. Our approach extends the classical work in radiosity by including a subsurface scattering matrix that operates in conjunction with the traditional form-factor matrix. This subsurface scattering matrix can be constructed using analytic, measurement-based or simulation-based models and can capture both homogeneous and heterogeneous translucencies. Using a fast iterative solution to radiosity, we demonstrate scene relighting and dynamically varying object translucencies at near interactive rates. © 2013 ACM.

关键词： Analytical models

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HLA based high-performance visualized simulation with MATLAB seamlessly embedded

HLA based high-performance visualized simulation with MATLAB...

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2013 4th International Conference on Material and Manufacturing technology, ICMMT 2013

作者： Zhang, Heng Yuan Xiong, Wei Fan, Peng Shan State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and Engineering Beihang University Beijing China The Academy of Equipment

ISBN: (纸本)9783037857526

In order to build multi-domain collaborative simulation systems, the method of making MATLAB programs join into HLA/RTI based distributed interaction simulation system needs to be studied. Aiming at giving full play to the advent-ages of MATLAB in visualization and engineering computing, improving the efficiency of collaborative simulation systems, this paper has proposed a method making MATLAB programs and SIMULINK modules seamlessly join into HLA/RTI based simulation system. The principles of the method are elaborated, and the designs of the related modules are introduced. The demonstrations and testing results show that the method could fully execute the visualized simula-tion functions of MATLAB, and has advantage in simulation efficiency over existing methods. © (2013) Trans Tech Publications, Switzerland.

关键词： MATLAB

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