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1、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 Prospec
2、ts 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
3、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 generate
4、d 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 peo
5、ple 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 informatio
6、n 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 artif
7、icial 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
8、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
9、 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 fron
10、t 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 an
11、d 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 Virt
12、ual 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 environmen
13、t 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
14、 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 fe
15、atures. 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
16、 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
17、 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 presentat
18、ion 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
19、 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
20、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.SpatialDataAcqu
21、isitionSystemHumandatacapturesystemComputerSystemsSupergraphicsworkstationsThree-dimensionalcontrolequipment3DdisplaydeviceCollectionAlternatelySpatial Data Acquisition SystemSpatial data acquisition system to obtain timely spatial data through satellite remote sensing, aerial remote sensing and glo
22、bal 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 environm
23、ental 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 stereo
24、scopic 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 po
25、sition 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 (D
26、egree 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
27、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 inc
28、ludes 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,
29、 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 r
30、esults 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 GISDeve
31、lopment 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 visual
32、ization 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 mu
33、ltidimensional 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
34、 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
35、 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
36、 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 computin
37、g 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 re
38、quirements 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 th
39、e network to use more flexible network architecture.CORBA-based naming service network VGIS system image concept map- NetworkVirtualGISclientApplicationServerNameManagementApplicationserver1Applicationserver2ApplicationservernAnalysisServerNameManagementSpatialAnalysisServices1SpatialAnalysisService
40、s2SpatialanalysisservicesnIII- 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 expre
41、ssion, 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 avat
42、arIn 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 imm
43、ersion 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
44、 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 h
45、ow 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, re
46、al-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,GMLandJava3Dtechnolog
47、ystrengthscomplementeachother,theuseofgraphicalmodelingcapabilitiesVRML,XMLinternationalization,structured,modularfeaturesandpowerfulJavanetworkprogramminglanguage,togetherformapowerfulvirtualrealityenvironments.IV-I VRMLIn 1994, the first session of the International Internet Conference in Geneva,
48、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 detec
49、tion.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， emissiveColo
50、r 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 informa
51、tion, 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 im
52、plemented 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
53、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 supp
54、ort 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 b
55、een 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,
56、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 (E
57、xtensible 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 us
58、e 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 t
59、echnology)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
60、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 pr
61、ovides 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
62、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 driv
63、er 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-geome
64、try 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-
65、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.3DS
66、MAX 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 t
67、he 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
68、。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 terr
69、ain 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, i
70、nteractive 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
71、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
72、 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 co
73、mplete 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 Flig
74、ht 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 f
75、rom 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 perfor
76、mance 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
77、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 cl
78、ear 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 mou
79、se, 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 -Au
80、toCad 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 sc
81、ale 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 an
82、d 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
83、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
84、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)
85、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
86、 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) co
87、de, 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
88、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.Ad
89、justthesky,cloudsandotherenvironmentalparameters;canalsoaddthecarandothermobileobjectsinthescene.vThrough the parameter configuration, in the computer systemestablished on the simulation of real, Nanjing Normal University,NanjingXianlinCampussimulationvirtualenvironment.Atthistime,the use of helmet
90、(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 problem
91、sThemainexistingproblems:vSoftwarevHardwarevOtheraspectsSoftwarevRealizationofcomplexlogiccontrolvSimulationrealtimeinteractionvAlltheintelligentbehaviorofhumanbrainvTosimulatethecomplextemporalandspatialrelations,theproblemofthesynchronizationbetweentimeandspacevTheexpressionoffeelings,includingthe
92、humanhearing,thevisual,thetactile,thetasteandthesmellcomputerExpressvRealtimedatacollection-compression-Analysis-decompressionvThepositioningofinteractionbetweenvirtualenvironmentandvirtualenvironment.HardwarevDatastoragedevicerequirements,animationimagestoragerequiresagreaterstoragecapacityofthedev
93、icevImagedisplayequipmentvDataacquisitionandprocessingsystemvVirtualrealitytechnologyoperationequipmentOther 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
94、 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 interac
95、tivity 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 p
96、roblems 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
