Virtual reality technology The main content I OverviewII VR hardware and interaction devicesIII Virtual Reality and GIS networkIV Virtual reality technology develops V virtual environment modeling and tools VI development example: Virtual Campus Xianlin Campus of Nanjing Normal UniversityVII Prospects and ProblemsAppendix: ReferencesI Outline Virtual reality is the development of computer technology is highly crystalline and is reflected in the various fields in the application process, including not only graphics, image processing, pattern recognition, network technology, parallel processing technology, artificial intelligence and other high-performance computing technology, but also involves mathematics , physics, communications, and even related to meteorology, geography, aesthetics, psychology and sociology.I-I What is virtual realityVirtual reality or virtual environment is generated by a computer having spot feeling environment, it is a new interactive system.Virtual reality technology is essentially a highly realistic simulation of human vision in real life. Hearing. Action and other acts of interactive technology.Traditional information processing environment has been a people adapt computer, while todays goal or idea is to gradually make computer adaptation and people called for the adoption of sight, hearing, touch, smell, and body, gesture or password, to participate in the information environmental treated to thereby obtain an immersive experience. This information processing system is no longer based on the one-dimensional digital space, but on a multidimensional information space. Virtual reality technology is a key technology to support this multi-dimensional information space.I-II Virtual Reality FeatursImmersionInteraction ImaginationImmersion vAn artificial computer generated virtual environment, this virtual environment is a three-dimensional digital models constructed by computer graphics, programmed into a computer to produce realistic virtual environment, allowing users to generate an immersive virtual environment visually the feeling, which is a sense of virtual reality technology immersion (Immersion) or spot a sense of participationInteractionModel and the traditional three-dimensional animation and virtual reality are usually generated by CAD systems is not the same, it is not a static world, but an open, interactive,virtual reality environment can influence by controlling and monitoring devices or users Effects, which is the second feature VR, i.e. interaction (Interaction).ImaginationVirtual reality is not just a demonstration of media, but also a design tool. It reflects the visual form designer ideas, such as when the front cover of a modern building, the first thing you do is for the buildings structure, beautiful idea to do detailed, in order to make quantitative, you need to many design drawings, of course, these drawings only insiders understand, virtual reality can put this idea into a visible virtual objects and environments, so that in the past only with traditional sand table design patterns upgrade to digital-per-view income that is perfection, greatly improving the quality and efficiency of the design and planning. This is the third category of VR has features that imagination (Imagination).I-III Virtual Reality classificaionDesktop Virtual RealityImmersive virtual realityAugmented Reality of Virtual RealityDistributed Virtual RealityI- IV The difference between virtual reality and three-dimensional animation Virtual Reality Three-dimensional animation A combination of digital virtual environment model based on real data from strict compliance with the standards and requirements of the project design, a scientific simulation systems. ? Manipulator experience the virtual three-dimensional space, immersive.Of scenes painted directly by the animators made according to the material or imagined together, and real environments and data have a big gap, belonging to demonstrate class works of art. ? Presupposed observation path can not be changed. The operator can feel the movement to bring real-time scene changes, walking scene, and personally arranged the scene, with two-way interactive features. Only one-way presentations as movie scene change, making the screen requires prior generation, time-consuming, laborious and costly. Virtual RealityThree-dimensional animationSupports stereoscopic display and 3D stereo, three-dimensional reality.Does not supportNo time limit, can show a true and detailed, and you can export files in virtual reality animated video based on the same data can be used for the production of multi-mode body and publicity, cost-effective.Animation by the time limit, can not be detailed display, low price. In real-time three-dimensional environment, adjustment support programs, assessment, management, information inquiry and other functions, suitable for larger complex project planning, design, bidding, approval, management and other needs, but also has a more realistic and intuitive multimedia presentation capabilities.Only suitable for simple presentation capabilities.I-V Virtual reality technology used in the real worldMany game makers, in order to make the game more realistic character movements, often will use the motion capture system.Virtual reality technology use in the film.Example: MatrixDisplay of goods (such as home, appliances, etc.)II VR hardware and interaction devicesA typical system consists of virtual reality space data acquisition system, the human data capture systems, three-dimensional display device, as well as three-dimensional control equipment and a computer system. Spatial data acquisition system, human data capture system in a virtual environment to establish space model; 3D display device, a three-dimensional control equipment belong to the same three-dimensional interactive equipment, design and manufacture of 3D interactive device superior performance is the key to virtual reality technology.SpatialDataAcquisitionSystemHumandatacapturesystemComputerSystemsSupergraphicsworkstationsThree-dimensionalcontrolequipment3DdisplaydeviceCollectionAlternatelySpatial Data Acquisition SystemSpatial data acquisition system to obtain timely spatial data through satellite remote sensing, aerial remote sensing and global positioning systems, and establishing an accurate and reliable virtual reality space environment. Remote sensing is an advantage of the inherent characteristics of electromagnetic radiation reflected from an object and through implementation of electromagnetic waves, there are technical environmental conditions and object recognition object.Human data capture systemHuman data capture device that can record the body of practical data and actions, including the body movements, facial expressions, physiological index, smell and voice.Interactive 3D EquipmentCommon 3D display device and stereoscopic helmet mounted display glasses.Helmet mounted display with three-dimensional drawing techniques to produce two spaced apart perspective, and directly displayed to the user corresponds to the left and the right eye on two monitors. The new helmet-mounted displays are accompanied by magnetic position sensor, can measure the direction of the users line of sight, so the scene can change as the users line of sight and make the appropriate changes.Interactive 3D EquipmentA common feature of the three-dimensional space control device is capable of controlling at least six degrees of freedom (Degree of Freedom), corresponding to the three-dimensional object describing the width, height, depth, pitch (pitch) angle, rotation (yaw) angle and yaw (roll) angle. Common three-dimensional control device has data gloves, track ball, three-dimensional probe, three-dimensional and three-dimensional mouse control lever and the like.The emergence of the data glove, virtual reality system provides a new interactive tool that can provide users with a very real and natural three-dimensional interactive tools.High-performance computer systemsHigh-performance computer system processing technology includes data conversion and data preprocessing technologies; real-time, realistic graphics image generation and display technology; multidimensional information data fusion, data compression, and generate the database; multiple sound synthesis and sound space technology; including command recognition, voice recognition, and detect gestures and facial expressions of information, including a pattern recognition; distributed and parallel computing, and high-speed, large-scale remote network technology.III Virtual reality and networks, GISVirtual reality technology now combines the latest research results in various disciplines, including the results of computer science, communication network technology, geographic information systems, remote sensing science and other areas. The main contents of this section:Virtual GISNetwork Virtual GISDistributed GISGeographical synergyIII-I Virtual GISDevelopment of computer science and human-computer interface technology in graphics, especially the promotion of virtual reality technology for GIS provides a new analysis geoscience data and technology platform to explore issues, and promote the GIS technology with virtual reality technology and visualization fusion technology, expanding the multi-dimensional GIS, three-dimensional GIS in particular connotation study provides new spatial data analysis models and new GIS application mode. Current international call this virtual reality technology and scientific visualization technology designed multidimensional GIS system called Virtual GIS system Virtual GIS (VGIS).III-II Network Virtual GIS presentationCombined with the current direction of the virtual network is a GIS development. Combined with network technology, network virtual GIS not only for people to analyze spatial data and spatial problem solving network provided by the technology platform, through immersive virtual reality model for people to interact through virtual geospatial offers the possibility, thereby for the study of virtual geographical environment provides an ideal platform.Network Virtual GIS architecture1.A GIS is a virtual network-based GIS, virtual reality system with the GIS Client-linking provides a simple spatial analysis or to analyze the results of GIS into virtual reality system to support virtual reality system data format, for virtual reality systems to observe;2. Another virtual GIS is based on a distributed virtual reality system, extend the ability to support spatial data types in a virtual reality system, providing simple spatial analysis.The overall structure of WEB virtual GISIII-III GIS system architectures role in the network virtual 3.3 CORBACORBA is one of the mainstream computing platform for distributed objects, CORBA platform to become widely accepted by the computer industry, and is fully open to the distributed network platform. CORBA is a distributed object-based design having scalability, security, load balancing and fault tolerance, real-time, special performance requirements for the design of distributed systems provide a rational platform. CORBA-based network platform to design virtual GIS, by reusing the CORBA network structure and basic network services greatly simplify virtual difficulty GIS network architecture design based on virtual GIS CORBA allows the network to use more flexible network architecture.CORBA-based naming service network VGIS system image concept map- NetworkVirtualGISclientApplicationServerNameManagementApplicationserver1Applicationserver2ApplicationservernAnalysisServerNameManagementSpatialAnalysisServices1SpatialAnalysisServices2SpatialanalysisservicesnIII- IV VGE and geographic synergiesVirtual Geographic Environments, is an avatar-based multi-user distributed intelligent three-dimensional virtual environment, a digital geo-spatial phenomena and laws of a particular geographical environment with multi-channel-aware expression, calculation and simulation, integrated management of the Earth can be used for multi-dimensional information and multimedia integrated publishing, interactive / innovative blend of style earth science research, and other distributed collaborative planning, design and decision-making.User avatarIn the virtual geographic environments, both user avatar can communicate face to face in the same virtual location. The incarnation as an expression of real users, and its source can contain visual, auditory and even taste a variety of information sources, etc., so that the user has a sense of immersion can be immersive feel itself is a virtual geographic environments part. Seeing and hearing other information sources may be co-workers to communicate what the real attitudes and emotions, is an important part of communication between co-workers in virtual geographic environments, and analysis of geographic data in planning and decision-making also plays a very important effect.AC ModeFor virtual geographic environment is not only a real geographical background, but also to provide a reliable platform for the exchange of information co-workers are. To this end, we need more research on how to improve communication modes between people and enhance various exchanges avatar in virtual geographic environments between.Currently, in accordance with the timeliness of the exchange of classified-o Non-real-time communication: e-mail and bulletin boardo Instant communication: interactive, real-time, including the traditional two-dimensional scenes, three-dimensional scene, streaming media technology and integration mode.IV The main development of virtual reality technologyVRMLXMLX3DJava3DVRMLXML地理实体地理实体X3DX3DJAVA3DInthevirtualrealitytechnology,VRML/GeoVRML,XML,X3D,GMLandJava3Dtechnologystrengthscomplementeachother,theuseofgraphicalmodelingcapabilitiesVRML,XMLinternationalization,structured,modularfeaturesandpowerfulJavanetworkprogramminglanguage,togetherformapowerfulvirtualrealityenvironments.IV-I VRMLIn 1994, the first session of the International Internet Conference in Geneva, Switzerland, proposed to create a three-dimensional network interface to facilitate network transmission VRML.In 1995, VRML1.0 version launched.In 1996, based on the 1.0 version of the major improvements introduced in version 2.0, which adds interactive scenarios, multimedia support, collision detection.In 1997, after an assessment standards organizations, VRML2.0 become the international standard, and renamed the VRML97.VRML simple examplesphere.wrl#VRML V2.0 utf8Shape # Define node contains two properties appearance Appearance # Appearance properties material Material #material， emissiveColor 1 0 0 # Reflective material geometry Sphere # Geometric properties radius 1IV-II XML XML full name in English is Extensible Markup Language, the Chinese translation for extensible markup language. It is an exchange standard by the W3C (World Wide Web Consortium) the promotion of structured information, and has been widely used. VRML adopt XML as the encoding of the main reasons is because with the international nature of XML, structured format and modular objects and other advantages. Has been clearly established by the implementation of the XML specification, X3D XML-syntax is easy to be implemented without the need for a huge reverse engineering (reverse engineering).XML and GISWhat role does XML play in GIS applications? We can use XML to define a query, in fact the traditional GIS query is no different, for example, can say, according to a user-specified area flooded analysis, and returns the result, the response message may be based on the results of the analysis in XML format the following graphic. The difference lies in the traditional way, geographical data and requests unified XML queries included in a separate XML document, a response message also XML documents.XML support for custom tags, provides a powerful extension mechanism, which inevitably many unique mark appears GIS industry.XML与GISOpenGIS Consortium (OGC) launched a timely GIS XML tag set GML (Geography Markup Language), an XML application in GIS provides a good way of standardization, the industry has been supported by many companies.The use of XML, we can achieve many GIS tasks -vBrowse and generate images, such as SVG, VML and X3D formats;vData conversion can be performed, such as XSLT, Schema can be configured, such as DTD, XML Schema and the like; You can query data, such as Xpointer and XQL, etc., it can also be run on different platforms, such as PDA.IV-III X3D X3D full name is Extensible3D (X3D early name is called VRML-NG, VRML Next Generation). It is a scalable next-generation 3D graphics standard, and extended VRML97 features. The origin of the name is the integration of X3D XML (Extensible Markup Language) and VRML (Virtual Reality Modeling Language).X3D is VRML successor. VRML (Virtual Reality Modeling Language - Virtual Reality Modeling Language) is the original network 3D graphics ISO standard (ISO / IEC 14772).X3D goal1. Include VRML97 features. (X3D content can still use the techniques browse VRML)2. XML integration. (You can use XML to show VRML97 features)3. componentization. (Encapsulated by the magnitude of the core (core) technology, it can easily add new features)4. expandability. (Using the component to add new nodes and execute code in line with the core technology)5. Use the Java platform to ensure universalIV-IV JAVA3DDue to space modeling VRML, GML, X3D and other languages loader design deficiencies, there is an urgent need for a high-level programming language to replace the original scripting capabilities. Java network and platform independence as well as its strong support for the three-dimensional graphics, so he occupied an important position in the future development of the market in the three-dimensional.Java3D has put forward a new scheme, as the model-based technology platform and input devices depending on the model. It not only provides high-level constructor construction and operation of the 3D geometric objects, and use these constructors can also build any complexity the virtual scene, these virtual scene large cosmic objects, small microscopic particles.V Virtual Environment Modeling Methods and ToolsThe basic principle is to create a virtual environment modeling three-dimensional modeling software and real objects in three-dimensional space, like a three-dimensional model, and then get the properties and texture data to model real object rendering, simulation models made after the data conversion, and finally driver software into 3D real-time three-dimensional dynamic simulation demo.Environmental ModelingEnvironmental modeling processAUTOCAD and 3DSMAX combine three-dimensional dynamic simulationMultigen Creator and Vega three-dimensional simulationV-I Environmental Modeling Euclidean-geometry Fractal-geometry Physically Based Modeling Image Based Rendering Hybrid Modeling Technology: Physically Based Rendering and Image Based Rendering, is the future direction of the virtual environment modeling.V-II Environmental modeling process 现实世界数据和纹理采集三维建模仿真渲染数据输出实时驱动景观仿真V-III AUTOCAD and 3DSMAX combine three-dimensional landscape dynamics simulationAutoCAD and 3DSMAX software are two kinds of software in engineering field.AutoCAD software in the construction, editing a two-dimensional graphics features, easy to use, and open, there are LISP Auto programming language support and many other advantages.3DSMAX software has great advantages in 3D modeling, animation and rendering.VR data format conversionIn 3ds Max VR authoring system model, combined with the requirement of VR system, see whether to use such as LOD (level of detail) model, if need to use Max comes with a LOD plug-in directly generate the objects LOD model. Finally, according to the environment of the VR system editor will the model output for editing environment that can be received by file type, such as vrml97 or DXF format file.在AUTOCAD 中进行精确的二维建模，生成*.dwg 文件。在3DS MAX 中制作成效果图和动画输出。处理和制作各种纹理贴图，并在3DS MAX 中作立体渲染。导入3DS MAX 中建立三维立体模型。V-IV Multigen Creator and Vega dynamic simulation of three-dimensional landscapeThe Multigen Creator Software, developed by MultiGen - paradigm, an American company, it has for real-time application optimization of open flight data format, powerful polygon modeling, vector modeling, large area terrain and generate accurate function, and a variety of professional options and plugins, can generate real-time three-dimensional (RT3D) database, and optimization, and closely combined with the subsequent real-time simulation software in the visual simulation, simulation training, urban simulation, interactive games and engineering applications, the scientific visualization real-time simulation field has a world leading position. AUTOCAD 和3DS MAX 结合进行三维建模，生成*.3ds文件。维建模，生成*.dwg 文件。导入Multigen Paradigm CREATOR 中对三维立体模型进行纹理贴图和渲染，并输出为OPENFLIGHT 文件（*.flt）。把OpenFlitht 文件导入Multigen Paradigm VEGA 中对三维立体模型进行实时动态驱动，实现漫游和动画输出功能。More professional modeling tools and professional modules Bundle Terrain (large area accurate 3D terrain function integration, need Pro Creator module);Road Tools（ Standard road generation tool，and Base Creator、Creator Pro Could bind）。Paradigm-Vega Efficient tools for building advanced real-time simulationVEGA is a leading software environment for the development of real-time visual and auditory simulation, virtual reality and general video applications. Vega including lynx graphical environments, a set can provide the full software control and maximum flexibility and complete application programming interface and a series of related database and AudioWorks2 real-time multichannel audio system. Vega and the optional module can run in Windows NT operating system and SGI IRIX operating system, and supports a variety of database loader Flight Open format and APIs Flight Open is the most popular standard file format in the field of visual simulation for Multigen development. Open flight using geometric hierarchy and node attributes to describe the three-dimensional objects, allows the user to operate directly on the hierarchical structure and node and guarantee from the large database to precise control of objects of a single vertex.Logic hierarchical structure and level of detail, the interception of the group, rendering priority, separation surface and other functions, the image generator know when and how to draw the 3D scene, greatly improves the performance of the real-time system. Flight APIs Open (C language development environment), you can expand the existing functionality and algorithms, develop user-defined database entitiesMultigen Creator/VegaSimulation Applications虚拟洛杉矶虚拟深圳中心区VI examples of the development of the virtual campus: Xianlin Campus of Nanjing Normal University Virtual campus is in the environment of computer, virtual reproduction of the new campus landscape, through the helmet, 3D devices such as a mouse, people can enter the virtual campus roaming, the beauty of the taste of the campus. In this way let more people a clear understanding of the new campus,for the regions development planning and t ransport, tourism and other aspects have more clear goals.Hardware and software environmentHardware equipment: two SGI octane workstation, Intergraph NT workstation, a 550 P III IBM microcomputer, helmet, joystick, 3D mouse, eyewear, Intergraph and high-precision scanner, recorder, tape machine (4mm), external 50g hard disk;Support: Digital Photogrammetry software VirtuoZo 3.1; GIS software -Arcinfo7.1, Arcview3.1, IMAGIS, VR software -MultiGen, Vega; image processing software Photoshop 5.0; 3D modeling software -AutoCad 3D Max, software.Step 1: data preparation phase (1) the original data, including Nanjing Normal University Xianlin Campus of large scale aerial (photo images scale 1:2500); camera calibration parameter file, ground control point in the document.(2) meta database construction include: aerial scale denominator; Gao Hang; aerial camera focal length; aerial units; date of aerial photography; aerial; number of aerial images; Gauss Kruger projection with a number; zones; central meridian and standard parallels.Step 2: data preprocessing stageData collection: the aerial photograph is scanned and digitized into digital photogrammetry software. The VirtuoZo3.1 establish the Xianlin Campus of Nanjing Normal University Digital Elevation Model (DEM), obtain ortho images and measured the area of the building model data and roads, lakes and other attribute data.Data conversion: data acquisition phase of the data through data conversion, respectively, according to terrain data, cultural data and construction data and other way into the virtual reality modeling software MultiGen. After the completion of the conversion process, users of the successful implementation of the conversion between heterogeneous systems, measurement data through GIS conversion required to create a virtual digital city data formats, such as digital elevation model data (DED), digital culture data (DFD), architectural models FLT data, several texture according to TIFF or jpg format.Step 3 data modeling phase(1) terrain data processing: the digital elevation model data (DED) by selecting the appropriate algorithm to build the 3D surface model, according to corresponding to surface model and the latitude and longitude, posted on the ortho image map as the texture of a surface, the formation of Xianlin Campus true three-dimensional landform landscape view.(2) attribute data processing: Cultural DFD of digital data, such as roads, lakes, according to the different object attribute hierarchical input MultiGen, choice or re establishment of corresponding feature code FeatureID and surface material (SMC) code, giving the appropriate texture. Then select the appropriate projection method, according to the latitude and longitude coordinates projected onto the landscape, get more outstanding and real landscape.(3) building data processing: the building model data FLT is opened in the MultiGen, paste the real texture, and then superimposed to the landscape.Step 4 to create a virtual reality systemvUsetheresultsoftheabovedata,intothevisualsimulationsoftwareVega, configure the appropriate driver environment, set the displaymodeforthehelmetorthree-dimensionalglasses,theinputmodeforthemouseorjoystick.Adjustthesky,cloudsandotherenvironmentalparameters;canalsoaddthecarandothermobileobjectsinthescene.vThrough the parameter configuration, in the computer systemestablished on the simulation of real, Nanjing Normal University,NanjingXianlinCampussimulationvirtualenvironment.Atthistime,the use of helmet (or three-dimensional mirror), joystick (three-dimensional mouse), users can immerse in this virtual realityenvironment.vUsing the function and interface provided by Vega, the twodevelopmentiscarriedout,andtheinteractiveoperationinthevirtualenvironmentisrealized.VII development prospects and problemsThemainexistingproblems:vSoftwarevHardwarevOtheraspectsSoftwarevRealizationofcomplexlogiccontrolvSimulationrealtimeinteractionvAlltheintelligentbehaviorofhumanbrainvTosimulatethecomplextemporalandspatialrelations,theproblemofthesynchronizationbetweentimeandspacevTheexpressionoffeelings,includingthehumanhearing,thevisual,thetactile,thetasteandthesmellcomputerExpressvRealtimedatacollection-compression-Analysis-decompressionvThepositioningofinteractionbetweenvirtualenvironmentandvirtualenvironment.HardwarevDatastoragedevicerequirements,animationimagestoragerequiresagreaterstoragecapacityofthedevicevImagedisplayequipmentvDataacquisitionandprocessingsystemvVirtualrealitytechnologyoperationequipmentOther aspectsThe physiological and psychological problems caused by the combination of the actual situation are the last difficult points of establishing the harmonious man-machine environment. For example, a long unsolved phenomenon existing in the flight simulator in the past, the simulator of vertigo.Howtodealwiththedifferenceandconnectionbetweentherealworldandthevirtualworld.Future outlookAlthough there are still many problems to be solved and breakthrough. In order to improve the interactivity of the VR system, realistic and immersion sense in new sensing and perception mechanism, geometric and physical modeling method, high performance computing, especially in high speed image processing, and artificial intelligence, psychology, sociology, and other aspects have many challenging problems to be solved. However, the virtual reality is a new and high technology with unlimited energy and great potential application.ReferenceCourseware: Virtual Reality (VR) Ma YiThe dynamic simulation technology of urban 3D Landscape Based on GISDesign of virtual GIS based on XML and CORBAVirtual reality and related technology Research on the construction method of Virtual City Thank you