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2011 International Conference on virtual reality and Visualization, ICVRV 2011

作者： Zhang, Fengquan Wu, Jiawen Shen, Xukun State Key Laboratory of Virtual Reality Technology and System Beihang University Beijing China

ISBN: (纸本)9780769546025

This paper presents an up-to-date survey on the application of Smoothed Particle Hydrodynamics (SPH) method in fluid simulation. As a pure Lagrangian method, it has a wide range of applications in computer graphics. We summarize it from key issues of kernel function, neighborhood search, boundary conditions, time integral to algorithm application in diverse fluids, including bubble, fluid-solid interaction, multiphase flow and mixed flow. We also discuss the hotspots area, including adaptive sampling, flow control, surface rendering and accelerating algorithm. In experiment section, we show four different animation scenes based on the survey algorithm in our platform. In the end, we point out the potential problems and prospects for future work. © 2011 IEEE.

关键词： Surveys

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Feasibility of a tele-rehabilitation system with corrective-force

Feasibility of a tele-rehabilitation system with corrective-...

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2011 International Conference on virtual reality and Visualization, ICVRV 2011

作者： Wang, Xibo Li, Jiting State Key Laboratory of Virtual Reality Technology and System Beihang University Beijing China

ISBN: (纸本)9780769546025

This paper proposes a tele-rehabilitation system based on virtual reality (VR) and haptic interaction technologies. The proposed system allows the therapist to remotely monitor the patient's rehabilitation exercise and provide force to correct the patient's movement if it is unexpected. The force is generated according to the force model defined at the server side. It is important for the therapist to know the magnitude of force applied on the patient as excessive force may harm the patient. Experiment results demonstrate that the proposed system is feasible and that the therapist can correct patient's movement effectively through providing force. © 2011 IEEE.

关键词： virtual reality

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3D Dental Model Segmentation with Geometrical Boundary Preserving

arXiv

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arXiv 2025年

作者： Xi, Shufan Liu, Zexian Chang, Junlin Wu, Hongyu Wang, Xiaogang Hao, Aimin State Key Laboratory of Virtual Reality Technology and Systems Beihang University China College of Computer and Information Science Southwest University China Peng Cheng Laboratory China

3D intraoral scan mesh is widely used in digital dentistry diagnosis, segmenting 3D intraoral scan mesh is a critical preliminary task. Numerous approaches have been devised for precise tooth segmentation. Currently, the deep learning-based methods are capable of the high accuracy segmentation of crown. However, the segmentation accuracy at the junction between the crown and the gum is still below average. Existing down-sampling methods are unable to effectively preserve the geometric details at the junction. To address these problems, we propose CrossTooth, a boundary-preserving segmentation method that combines 3D mesh selective downsampling to retain more vertices at the tooth-gingiva area, along with cross-modal discriminative boundary features extracted from multi-view rendered images, enhancing the geometric representation of the segmentation network. Using a point network as a backbone and incorporating image complementary features, CrossTooth significantly improves segmentation accuracy, as demonstrated by experiments on a public intraoral scan dataset. The source code is available at https://***/XiShuFan/CrossTooth_CVPR2025 Copyright © 2025, The Authors. All rights reserved.

关键词： Image segmentation

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Implementation and Verification of a virtual Testing system Based on ROS and Unity for Computer Vision Algorithms 12

Implementation and Verification of a Virtual Testing System ...

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12th International Congress on Image and Signal Processing, BioMedical Engineering and Informatics, CISP-BMEI 2019

作者： Zhang, Qian Zhao, Yongjia State Key Laboratory of Virtual Reality Technology and System Beihang University Beijing China

ISBN: (纸本)9781728148526

With the development of artificial intelligence technology, Computer vision algorithm is playing an increasingly important role. Computer vision algorithm testing is a vital link to ensure the safe and reliable operation of agents. However, the traditional testing methods based on real scenes provide single samples and are challenging to obtain ground truth, which makes it inefficient to test computer vision algorithms. To solve this problem, the testing method of computer vision algorithms using virtual scenes instead of real scenes has been applied. In this paper, Unity and robot operating system (ROS) are selected to build a virtual testing system named URCV for computer vision algorithms. The feasibility of the system and the influence of virtual scene elements on the testing of the monocular ORB-SLAM2 algorithm are verified, including the rendering path of Unity's RGB camera, texture accuracy, and illumination model. © 2019 IEEE.

关键词： Robot Operating system

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Current closed loop control for increasing virtual stiffness in haptic interaction

Current closed loop control for increasing virtual stiffness...

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2008 IEEE/ASME International Conference on Mechatronics and Embedded systems and Applications, MESA 2008

作者： Xiaowei, Dai Yuru, Zhang Yonggang, Cao Dangxiao, Wang State Key Laboratory of Virtual Reality Technology and System Beihang University Beijing China

ISBN: (纸本)9781424423682

virtual stiffness is a critical performance measure for haptic devices. This paper proposes a new controller to increase the virtual stiffness. The design of the controller is based on theoretical analysis of the system stability condition, which indicates that by adding a current closed loop the stability can be increased. We implemented the current closed loop controller with a first order filter and a PID control law. With properly selected parameters of the filter and the PID controller, it is possible to increase the maximum achievable virtual stiffness. Experimental results demonstrate the effectiveness of the proposed method. © 2008 IEEE.

关键词： system stability

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Hydraulic flow simulation on dynamical changing terrain

Hydraulic flow simulation on dynamical changing terrain

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2010 International Conference on Computational and Information Sciences, ICCIS2010

作者： Hao, Aimin Zhu, Shiwu Li, Shuai State Key Laboratory of Virtual Reality Technology and System Beihang University Beijing China

ISBN: (纸本)9780769542706

Water simulation and terrain change are both important aspects in computer graphics and useful in producing realistic interactive environment. We present a step to combine the two phenomena together. In our system terrain is carefully organized to make it can be modified easily. The water flow is calculated by the shallow water simulation, which is a 2D simplification of Navier-Stocks equations. When the terrain is changed by external force, the stream's original path may be broken or form new branches, meanwhile the water flows through the new path accordingly. We design the method skillfully to make it suits the GPU's multi-kernel architecture, so can take full advantage of the parallelism of current powerful graphics hardware. Our experiments demonstrate that the proposed method is suitable for real-time simulation of a variety of scenes including tracks on wetland, river diversion, adding obstacles into the water, etc. © 2010 IEEE.

关键词： Hydraulics

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Real-time approximate soft shadow rendering with bidirectional penumbra map

Real-time approximate soft shadow rendering with bidirection...

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International Conference on Educational and Information technology

作者： Wang, Lili Zhen, Jingchao Shen, Zhe State Key Laboratory of Virtual Reality Technology and System Beihang University Beijing China

ISBN: (纸本)9781424480340

The present traditional penumbra map method can only render the outer part of the penumbra, which breaks down when the umbra region significantly decreases because of the large light sources and the large distance between the occluder and the shadowed objects. This happens for very large area light source or as the occluder moves away from the objects it shadows. This paper proposes a real-time soft shadow rendering method based on bidirectional penumbra map generated in image space. It first extracts the edge of the shadow in the shadow map without rendering the whole scenes again. Then it extends the edges both inside and outside to obtain the inner and outer penumbra region, and calculate the change of lighting intensity along the two directions to generate the bidirectional penumbra map. Lastly, the final image is rendered with this penumbra map and the shadow map. This method solves the distortion problem of the traditional penumbra map method when the umbra region significantly decreases. It has only two rendering passes and approximates the soft shadow in image space, thus can be design to run entirely on GPU. The result of our experiments shows the efficiency of our approach. © 2010 IEEE.

关键词： Maps

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Extremum seeking control for UAV close formation flight via improved pigeon-inspired optimization

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Science China(Technological Sciences) 2024年第2期67卷 435-448页

作者： YUAN GuangSong DUAN HaiBin State Key Laboratory of Virtual Reality Technology and Systems School of Automation Science and Electrical EngineeringBeihang University(BUAA)Beijing 100083China

This paper proposes a comprehensive design scheme for the extremum seeking control(ESC)of the unmanned aerial vehicle(UAV)close formation *** proposed design scheme combines a Newton-Raphson method with an extended Kalman filter(EKF)to dynamically estimate the optimal position of the following UAV relative to the leading *** reflect the wake vortex effects reliably,the drag coefficient induced by the wake vortex is considered as a performance ***,the performance function is parameterized by the first-order and second-order terms of its Taylor series *** the excellent performance of nonlinear estimation,the EKF is used to estimate the gradient and the Hessian matrix of the parameterized performance *** output feedback of the proposed scheme is determined by iterative calculation of the Newton-Raphson *** with the traditional ESC and the classic ESC,the proposed design scheme avoids the slow continuous time integration of the *** allows a faster convergence of relative position ***,the proposed method can provide a smoother command during the seeking process as the second-order term of the performance function is taken into *** convergence analysis of the proposed design scheme is accomplished by showing that the output feedback is a supermartingale *** improve estimation performance of the EKF,a improved pigeon-inspired optimization(IPIO)is proposed to automatically tune the noise covariance *** Carlo simulations for a three-UAV close formation show that the proposed design scheme is robust to the initial position of the following UAV.

关键词： unmanned aerial vehicle close formation extremum seeking control Newton-Raphson method improved pigeon-inspired optimization

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A novel blind robust digital watermarking on 3D meshes

A novel blind robust digital watermarking on 3D meshes

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2nd International Workshop on Digital Media and its Application in Museum and Heritage

作者： Shu, Jun Qi, Yue Cai, Su Shen, XuKun State Key Laboratory of Virtual Reality Technology Beihang University China

ISBN: (纸本)9780769530659

A novel blind watermarking method on 3D meshes is proposed in this paper. PCA (Primary Component Analysis) is used for 3D meshes' preprocessing. Octree structure is obtained after octree partition of 3D meshes. Meaningful watermark is then embedded into SC (Single Child) nodes in bottom level of octree. This method is robust against translation, rotation, uniform scaling and vertex reordering attacks with a big embedding space. Higher nodes of octree are used to construct 'Zero-watermark', which can resist simplification, noise and remeshing attacks. This method can be used directly on point cloud as it does nothing with topology of meshes.

关键词： PICA octree-codec robust blind watermarking

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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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