虚拟现实环境下颅底肿瘤术前计划的制定

目的探讨虚拟现实(virtual reality,VR)技术在颅底肿瘤术前计划制定中的作用。方法36例拟采用手术治疗的颅底肿瘤患者,分别采集磁共振成像(MRI)、磁共振动脉成像(MRA)、磁共振静脉成像(MRV),计算机体层摄影(CT)等多种医学影像数据,输入Dextroscope术前计划系统,在VR环境中进行重建、融合、提取、染色,标记等处理还原为一个空间立体的三维物像。再利用工具进行观察,测量、手术模拟等操作,从而在术前充分获得肿瘤,脑组织,颅底骨质以及神经血管全面而直接的信息,制定周密的手术计划,并与真正手术中情况进行对照比较。结果36例病例均成功地实现了三维立体虚似现实影像的重建,术前计划中对于肿瘤及其颅底解剖结构特征的判定与术中实际情况吻合。结论Dextroscope系统的虚拟现实技术能快速、直观、全面地整合颅底肿瘤多种医学影像数据,以提供肿瘤及其颅底解剖结构的综合信息,在手术前为制定和优化手术方案提供帮助,有可能有助于提高了手术的安全性与病灶的全切除率。

基于虚似现实的三维场景建模的可视化实现

本文从虚拟现实的角度 ,运用OpenGL技术以三维图形建模予以探讨 ,给出了类的设计 ,并应用该理论实现了三维虚拟场景的可视化。

虚拟现实技术在煤矿安全工程中的应用

虚拟现实技术与安全工程相结合,有效地提高了施工过程中的安全性。所以,虚拟现实技术与安全工程相结合是至关重要的。本文在介绍虚拟现实技术概念的同时,对虚拟现实技术在煤矿安全工程中的应用现状进行分析。

虚拟实体对象建模语言SCPL

本文给出一种新的虚拟实体对象建模语言ＳＣＰＬ．这种语言以基于控制论的行为模型ＳＣＰ为中心组织虚拟实体对象的建模，具有实现连续和更复杂行为的能力，适用领域较广．ＳＣＰＬ将行为的控制封装于对象内部，同时行为又可在虚拟实体对象类外部单独定义，可重用性好．ＳＣＰＬ还以自然的方式支持把具有行为的虚拟实体对象作为子对象．应用情况表明，该语言程序具有程序简洁明了，执行效率较高的优点，有效克服了已有建模语言在行为建模。

核动力装置用阀门的虚拟维修训练

介绍了虚似现实系统的技术特点 ,并结合核动力装置用阀门的特殊性 。

基于模糊神经网络的手势识别

本文通过对人手结构和手关节运动的分析 ,建立了手模型及其相应的数据结构 .由数据手套的数据接口获取各指节的曲伸角度 ,建立手势标准样本库 ,并提出了采用模糊神经网络进行手势识别 ,用手势标准样本加以训练 ,使其具备识别手势的功能 .试验结果表明 。

Design of research platform on telerobot system based on virtual reality technology

A design strategy for a research platform of a telepresence telerobot system based on virtual reality technology is put forward. The design frame of the system is described, and its important core techniques are described. An octrees data structure is utilized to build kinematic and dynamic modeling of the virtual simulation environment, Delphi+OpenGL+3DS MAX are adopted to carry through the virtual modeling and visible simulation exploitation of the slave-robot and its environment. Photo-correction is adopted to correct positioning deviation of the virtual geometric model and modeling errors. The cost of software and hardware equipment for the research platform realized is low. The master/slave robot (manipulator) system and all software in the system were designed and manufactured by our research group. The performance of the system has reached the level required for research. An indispensable experiment base is provided for the research of a telepresence telerobot system based on virtual reality technology.

AN ALGORITHM OF DISTANCE CALCULATION BETWEEN A BOUNDING SPHERE AND A BOUNDING CSG PRIMITIVE

A simple method for calculating distance between a solid sphere and a constructive solid geometry (CSG) so lid primitive (including block, cone, cylinder, sphere, wedge and torus) is derived to support the collision detection algorithm. By decomposing the whole space into relative positions and geometric features of the sphere and the primitive considered, closed form distance formula are got. These calculations are very useful in the real time collision detection in which primitives are used as bounding volumes of complex objects.

Application and Implementation of Quest3D Technology in Garden Landscape Design

The application of virtual reality technology has become more and more influential in garden design. Quest3D as a significant software to realize the virtual reality technology is utilized in this study to make a garden roaming demonstration system with the gardening design of a classical courtyard as an example. Besides, the advantages and disadvantages of applying Quest3D technology in garden landscape design are elaborated from the perspective of the selection of Quest3D technology, basic procedures for the selection and establishment of software and hardware.

A robot simulation system with virtual force display and feedback based on master manipulator

This paper describes a virtual environment, which can present dynamic force transformation during the control of objects. A 5-DOF haptic interface with the capability to generate kinesthetic effect is combined. In this system, the operator manipulates an object in a virtual environment by using the 5-DOF master arm. When contacting with the virtual object, the contact force can be calculated and shown in the graphic interface. The contact response and deformation of the virtual object, which are usually called haptic rendering, also can be performed. The study supplies an approach to improve the operator’s immersion and can be used in many tele-robot control fields.

VIRTUAL REALITY BASED THREE-DIMENSIONAL GUIDE WIRE PROPAGATION SIMULATION FOR ENDOVASCULAR INTERVENTION

The virtual reality based motion simulation of the guide wire and the catheter inside specific vascular structures can benefit a lot for the endovascular intervention. A fast and well-performed collision cancellation algorithm is proposed based on the geometric analysis and the angular propagation （AP）, and a 3-D real-time interactive system is developed for the motion simulation of the guide wire and the catheter inside the specific patient vascular. The guide wire or the catheter is modeled as the ＂multi-body＂ representation and properties are defined by its intrinsic characteristics. The motion of the guide wire or the catheter inside the vascular is guided by the collision detection and the collision cancellation algorithm. Finally, a relaxation procedure is used to achieve more realistic status. Experimental results show that the behavior of the guide wire or the catheter depends on the defined parameters. The real-time simulation can be achieved. The result shows that the simulation system is effective and promising.

实践形态的多样性

最广义的实践指人的活动与社会生活 ,实践的形态是多种多样的 ,应不断对实践形态的发展作新的概括。本文提出智力实践、信息实践、虚拟实践的新概念 ,以期引起学术界讨论。

Calibration Scheme Under Spherical Coordinates for Magnetic Tracker Used in VR System

A calibration scheme under spherical coordinates is described for a magnetic tracker used in VR (virtual reality) system. A look up table containing data of tracked values for certain positions in the working space, spe cified in spherical coordinates, is generated first, which is then used to calibrate the tracking results by a two dimensional interpolation. The scheme can effectively correct the static errors in the magnetic tracking system. The employment of spherical coordinates significantly reduces the calculation complexity in calibration.

Research on the Dynamic Simulation System of Maize Growth

Dynamic simulation system of maize growth is developed by the physiological and ecological model,morphological structure model,computer science and virtual reality technology,to improve the level of precise operation of maize production.The computer graphics algorithms,virtual reality technology,animation design and information integration technology are applied to maize production by this system.establishment of dynamic simulation system of maize growth is conducive to raise level of precise operation in maize production.The system also can assist the relevant production research and testing,to reduce cost and improve efficiency.

Radial Based Probabilistic Roadmap Motion Planning Method in Sparse Environment

A new dynamic path planning method in high dimensional workspace, radial based probabilistic roadmap motion (RBPRM) planning method, is presented. Different from general probabilistic roadmap motion planning methods, it uses straight lines as long as possible to construct a path graph, so the final path obtained from the graph is relatively shorter and straighter. Experimental results show the efficiency of the algorithm in finding shorter paths in sparse environment.

On 3D Geo-visualization of a Mine Surface Plant and Mine Roadway

Constructing the 3D virtual scene of a coal mine is the objective requirement for modernizing and processing information on coal mining production. It is also the key technology to establish a ＂digital mine＂. By exploring current worldwide research, software and hardware tools and application demands, combined with the case study site （the Dazhuang mine of Pingdingshan coal group）, an approach for 3D geo-visualization of a mine surface plant and mine roadway is deeply discussed. In this study, the rapid modeling method for a large range virtual scene based on Arc/Info and SiteBuilder3D is studied, and automatic generation of a 3D scene from a 2D scene is realized. Such an automatic method which can convert mine roadway systems from 2D to 3D is realized for the Dazhuang mine. Some relevant application questions are studied, including attribute query, coordinate query, distance measure, collision detection and the dynamic interaction between 2D and 3D virtual scenes in the virtual scene of a mine surface plant and mine roadway. A prototype system is designed and developed.

Visual fatigue relief zone in an extra-long tunnel using virtual reality with wearable EEG-based devices

Long-time driving and monotonous visual environment increase the safety risk of driving in an extra-long tunnel. Driving fatigue can be effectively relieved by setting the visual fatigue relief zone in the tunnel. However, the setting form of visual fatigue relief zone, such as its length and location, is difficult to be designed and quantified. By integrating virtual reality(VR) apparatus with wearable electroencephalogram(EEG)-based devices, a hybrid method was proposed in this study to assist analyzers to formulate the layout of visual fatigue relief zone in the extra-long tunnel.The virtual environment of this study was based on an 11.5 km extra-long tunnel located in Yunnan Province in China.The results indicated that the use of natural landscape decoration inside the tunnel could improve driving fatigue with the growth rate of attention of the driver increased by more than 20%. The accumulation of driving fatigue had a negative effect on the fatigue relief. The results demonstrated that the optimal location of the fatigue relief zone was at the place where driving fatigue had just occurred rather than at the place where a certain amount of driving fatigue had accumulated.

Study of virtual reality for mild cognitive impairment:A bibliometric analysis using CiteSpace

Objectives Non-invasive and low-cost virtual reality(VR)technology is important for early evaluation and intervention in mild cognitive impairment(MCI).This study aimed to demonstrate the current status of overseas and domestic research as well as the focus and frontier of VR technology among individuals with MCI through a bibliometric analysis.Methods Studies from the core collection of Web of Science™between 1995 and 2020 were used;furthermore,CiteSpace 5.7 R3 was utilized to analyse information on authors/cited authors,keywords,burst words,and cited references.Results In total,230 publications were identified.Most studies were published in the USA(45 publications)and Italy(41 publications),where Guiseppe Riva ranks first(14 publications),and Tarnanas I is the author with the highest centrality(0.44).The hot topics in VR applications in the MCI population are‘physical activity,’‘people,’‘single-blind,’‘disease,’‘walking,’‘technology,’‘working memory,’and‘risk’in recent years.The keyword‘mild cognitive impairment’has attracted extensive attention since 2012,showing the strongest citation outbreak(8.28).The clustering results of the literature show the research types and emerging trends,including‘exergame,’‘serious games,’‘spatial navigation,’‘activities of daily living,’‘exercise,’‘enriched environment’and‘wayfinding.‘Conclusions Cognitive assessment and nonpharmacological intervention research on patients with MCI have become the focus of dementia prevention in recent years.Virtual technology,combined with traditional methods such as exercise therapy,provides new ideas for innovative cognitive evaluation and cognitive intervention.

CAD-VR geometry and meta data synchronization for design review applications

In this paper we present the MEMPHIS middleware framework for the integration of CAD geometries and assemblies with derived Virtual Reality (VR) models and its specific meta data and attributes. The goal of this work is to connect real time VR applications, especially for the Design Review, with enterprise software storing and managing CAD models (Product Data Man- agement—PDM). The preparation of VR models requires expert knowledge, is time consuming, and includes selection of required CAD data, tessellation, healing of unwanted gaps, applying materials and textures, and special surface and light effects. During the Design Review process, decisions are made concerning the choice of materials and surface forms. While materials can be switched directly on the VR model, the modification of part geometries must be made on the CAD model. Our system synchronizes modi- fications of the original CAD geometries and of attributes that are relevant for the realistic rendering using the PLM Services standard. Thus, repeated work for the VR preparation can be avoided.

The Application of Virtual Reality Technology to Ear Microsurgery

The broad application of virtual reality (VR) to medicine has been of great value. The virtual surgery is one of technically difficult applications. With the expansion of the increasingly fine and complicated ear microsurgery, new methods are required to train the doctors. It is necessary and of practical significance to apply VR to the ear micro-operation, which is a functional operation with high precision and great difficulties. In this article, medical VR applications were reviewed. The application of VR to the ear microsurgery was discussed and the virtual ear microsurgery system was designed.