VR technology is a comprehensive science and technology that includes many disciplines in the field of computer technology, and has been applied in many fields in reality.
Virtual reality technology; Virtual reality technology
1. The concept of virtual reality technology
VR technology is a virtual reality technology, which enables people in reality to experience the same things and things as the real world in the virtual information world created by computers. It has the basic characteristics of multi-perception, immersion, interaction and conception. This virtual technology combines computer graphics and image technology, realistic simulation technology, multimedia technology and many other scientific technologies. It can simulate human visual, auditory, tactile and other sensory functions. By allowing people to communicate in real time through language and actions in the virtual world created by computers, it can be said that the development prospect of this technology is very broad.
2. Introduction of the characteristics of virtual reality technology.
(1) Multi-perceptual features refer to the perceptual systems such as vision, force, touch, movement, taste and smell. From the perspective of the development of human ideal virtual reality technology, it is hoped that all the senses in reality can be completely simulated. However, due to the limitations of current technology mastery and sensing technology, only the above-mentioned sensing systems such as vision, force, touch, movement, taste and smell can be simulated.
2 immersion, also known as immersion or presence, existence, etc. , especially the real experience that people exist in the virtual world in the first person. Of course, the current technology has not reached the optimal level.
③ Interactivity means that people can feel the interactive information between people and objects by grabbing and using some objects, just like in reality.
(4) Conception, that is, in the virtual world, what you want to do is presented in the virtual world. What effect can you achieve by doing this and what effect can you achieve by doing that? You can even conceive things that can't exist in the real world in the virtual world.
3. Application scope of virtual reality technology
VR technology has gone through decades from its birth to now, and its application scope is getting wider and wider, such as medicine, which can provide simulated surgery for doctors and greatly improve the success rate of surgery in reality, as well as military, science and technology, commerce, architecture, entertainment, life and so on.
4. Related technologies involved in 4.VR technology.
① Stereo visual reality technology: People get the most information through vision among all human senses, so stereoscopic display technology plays an indispensable role in virtual reality technology.
② Environment construction technology: In the virtual world, the component environment is an important part. To create a regional environment, we must first create an environment or building module, and then carry out real-time description and three-dimensional display on this basis, thus forming a virtual regional environment.
(3) Realistic real-time rendering technology: To achieve the same things as the real world in the virtual world, it is not enough to rely solely on stereoscopic display technology. Virtual world should have a sense of realism and real-time. Simply put, it is the technology to realize the weight, quality, color, relative position and occlusion relationship of an object.
④ Realization technology of virtual world sound: Although vision is one of the important ways to obtain information in virtual world, there are many sensory systems that can obtain surrounding information besides vision. For example, hearing, this technology is to realize sound in the virtual world, so that people can not only see but also hear in the virtual world.
5. Hardware equipment involved in 5.VR technology
① input device
Hardware input devices related to virtual reality technology can be divided into two categories: first, interactive devices based on nature are used for information input in virtual worlds; The other is a three-dimensional positioning and tracking device, which is mainly used to determine the position of the input device in the virtual world and transmit it to the virtual world.
There are many forms of natural interaction between virtual world and people, such as data gloves, data clothes, 3d controllers, 3D scanners and so on.
Data glove is a multi-modal virtual reality platform. Through software programming, it can grab, move and rotate objects in the virtual scene, and can also be used as a tool to control scene roaming. The appearance of data glove provides a new interactive means for virtual reality system. At present, the product can detect the bending of fingers and accurately locate the position of hands in three-dimensional space by using magnetic positioning sensors. This data glove, which integrates finger bending test and spatial positioning test, is called? Real gloves? It can provide users with a very real and natural three-dimensional interactive means.
Data suit is an input device designed for VR system, which is used to identify the whole body movement. This data set can measure about 50 different joints of human body, including knees, arms, trunk and feet. Through photoelectric conversion, the computer recognizes the motion information of human body. Through the boom display and data gloves, interactive data is put on a virtual reality coat.
② output equipment
In order to reflect the feeling of immersion in the virtual world, people must realize a variety of senses in the real world, such as vision, hearing, touch, strength, smell, taste and so on, but the current virtual technology only realizes vision, hearing and touch.
3 VR constitutes a device.
The composition of the virtual reality world, the main equipment is the computer itself, all the scenes in the virtual world are caused by models, and these models are made by computers. The general computer is divided into four parts: one is a high-profile personal computer, which is specially used for ordinary graphics to configure the accelerator card and is realized as a desktop function in VR technology; Second, the high-performance graphics workstation is a high-profile graphics processing computer; Third: highly parallel system computer; Fourthly, the distributed virtual realization of four categories, such as computers.
6. Discussion on the difficulties in virtual reality technology
With the continuous development of computers, the interaction between people and computers has been greatly improved. This technology has become the main means to establish VR technology. However, real-time reality has always been one of the major difficulties in the progress of VR technology. Theoretically, the virtual world with high fidelity and real-time roaming can be analyzed in real time, but at least in the current situation, it can not meet the theoretical requirements. This theory and technology need the support of powerful hardware configuration requirements, such as extremely fast graphics working computer and 3D graphics accelerator card. However, according to the current equipment, the fastest real-time graphics processing computer can not realize a very realistic virtual world of colleagues and real-time interaction. The fundamental reason is that when the interaction between people and the virtual world is introduced and a new dynamic model needs to be generated immediately, the real-time effect cannot be achieved, and the clarity of the graphics module has to be reduced to reduce the processing time, which directly leads to the reduction of the realism of the virtual world to a certain extent, which is the so-called scene complexity problem.
The generation of graphic module is an important bottleneck in virtual world. The important feature of the virtual world is the dynamic characteristics of the virtual world changing with the position and direction of people. Simply put, it is the scene of the graphic module that is generated immediately after you move the position and direction. There are two indicators to measure the effect and degree of user immersion in the virtual world. One is the dynamic characteristics mentioned above; The second is the delay characteristic of interaction. The frame number of natural dynamic graphics is 30, at least not less than 10, otherwise the whole picture will have a serious sense of discontinuity and movement. Interaction delay is another important indicator that affects users, such as the change of position and the control of direction when people fly on the plane. At this point, the system should immediately generate relative graphic images, and the time delay during this period should not be greater than 0. 1 sec, and at most should not be greater than 1/4 sec. Otherwise, in the long-term work, people will easily feel tired, irritable or sick, which will seriously affect them? Real? This feeling. The above two indicators are the speed of computer graphics processing. For dynamic module graphics generation, the graphics generation time of each frame is preferably between 30 and 50 milliseconds; For the delay of interaction, besides the interactive input and its processing time, the speed of graphic generation is also an important factor. The factors mentioned above are not only the factors of application technology, such as the complexity of virtual scene, the sense of reality required for the generation of graphics modules, etc., but also directly related to the hardware composition of graphics processing. 7. Research status of virtual reality technology in various countries
① Research status of virtual reality technology in the United States
The United States is the birthplace of virtual reality technology research, and the birth of virtual reality technology can be traced back to the 1940s. The virtual reality technology originally studied was only used by the US military for the simulation training of flight pilots and astronauts. However, with the sharp reduction of US military spending after the end of the Cold War, virtual reality technology has gradually turned to civilian use. At present, the basic research in this field in the United States mainly focuses on four aspects: perception, user interface, background software and hardware.
In 1980s, NASA and the U.S. Department of Defense organized a series of research on virtual reality technology, and achieved remarkable results. The national aeronautics and space administration Ames laboratory is dedicated to a project called. Virtual planet exploration? Experimental plan. Now, NASA has established a simulation training system for aviation and satellite maintenance, a simulation training system for space stations and a nationwide simulation education system. The computer major of the University of North Carolina is the earliest and most famous university to study virtual display technology. They mainly study molecular modeling, aviation driving, surgical simulation, architectural simulation and so on. George Mei Sen University has developed a real-time fluid simulation system in a dynamic virtual environment. Xerox's research center is mainly engaged in the research of establishing future office by using VRT in the field of simulated reality technology, and is committed to designing a window system based on simulated reality technology to make data access easier. Boeing's Boeing 777 transport plane adopts paperless design. The virtual environment is superimposed on the real environment by using the developed virtual reality system, and the virtual template is displayed on the workpiece being processed. Workers can control the size to be machined according to the template, thus simplifying the machining process.
Graphic image processing technology and sensor technology are the main technologies of the above VR project. At present, the dynamic of space and the real-time of time are the main concerns of this technology.
② Research status of virtual reality technology in Europe.
In Europe, Britain has developed some aspects of VR, especially in distributed parallel processing, auxiliary equipment (including tactile feedback) design and application research. It is in a leading position in Europe. British Bristol company found that the intersection of VR applications should focus on the overall integration technology, which is in a leading position in some fields of software and hardware. The telepresence research experiment of British company ARRL mainly includes virtual reality reconstruction. Their products also include architectural and scientific visualization computing.
Other developed countries in Europe, such as the Netherlands, Germany and Sweden, have also actively carried out the research and application of VR.
DIVE distributed virtual interactive environment in Sweden is a heterogeneous distributed system based on Unix, and multiple processes on different nodes can work in the same world.
The training and simulation system developed by TNO- PEL of TNO Institute in The Hague, the Netherlands, improves the existing simulation system by improving the man-machine interface, so that users can fully participate in the simulation environment.
Germany has achieved unexpected results in the application of VR. In the transformation of traditional industries, first, it is used for product design to reduce costs and avoid the risks of new product development; The second is product demonstration to attract customers to win orders; Third, it is used for training. Before the new production equipment is put into use, the virtual factory is used to improve the operation level of workers. ACM symposium-um Virtual Reality Software and Technology Conference held in France on June 27th-29th+10/October 27th, 2008 promoted the in-depth development of virtual reality technology as a whole.
③ Research status of virtual reality technology in Japan.
The development of virtual reality technology in Japan also plays an important role in the research of related fields in the world, and has made great achievements in establishing large-scale VR knowledge base and virtual reality games.
In the Precision and Intelligence Laboratory in tokyo institute of technology, we studied and established the humanized interface of 3D model, which is called SpmAR NEC Company. A virtual reality system is developed, which uses a substitute hand to process the three-dimensional human model in CAD. The processing of the model is connected with the operator's hand through the data glove; The Institute of Product Science of the Ministry of International Trade and Industry of Japan has developed a force feedback device using X and Y recorders. The research focus of the Advanced Scientific Research Center of Tokyo University is mainly on remote control. Their latest research project is to enable users to control the remote camera system and the master-slave system of the follow-up manipulator simulating human hands. The Guang Lai Research Office of the University of Tokyo focuses on the visualization of virtual reality. They are developing a virtual holographic system to overcome the limitations of current display and interactive technology; In 2004, a research team led by Professor Hiroshi Chihara of Nara Graduate School of Advanced Technology in Japan developed an olfactory simulator. As long as the fruit in the virtual space is put on the nose tip to smell, the device will emit the fragrance of the fruit at the nose tip, which is a breakthrough of virtual reality technology in the field of olfactory research.
④ Research status of virtual reality technology in China.
Compared with some developed countries, China still has a long way to go in the research of virtual reality technology. With the rapid development of computer graphics, computer system engineering and other technologies, virtual reality technology has received considerable attention and attracted the interest and attention of people from all walks of life in China. The research and application of VR, the establishment of virtual environment and virtual scene model, and the development of distributed VR system are all developing in depth and breadth. The Ministry of Science, Technology and Industry for National Defense of the State Science and Technology Commission has listed the research of virtual reality technology as a key research project, and many domestic research institutions and universities are also conducting research and application of virtual reality, and have achieved some good research results.
The Computer Department of Beihang University is also one of the earliest and most authoritative institutions to carry out VR research in China. Its virtual realization and visualization new technology laboratory integrates distributed virtual environment, which can provide real-time three-dimensional dynamic database, virtual reality demonstration environment, virtual reality system for pilot training, virtual reality application system development platform and so on. , and has made progress in the following aspects: focusing on the representation and processing of physical characteristics of objects in virtual environment; In the visual interface of virtual reality, some hardware is developed, and related algorithms and implementation methods are put forward.
Made by Tsinghua University National Optical Disc Engineering Research Center? Potala Palace? Using QuickTime technology, a panoramic VR system is realized. Zhejiang university CAD&; CG State Key Laboratory has developed a real-time roaming system for desktop virtual building environment. The computer department of Harbin Institute of Technology has successfully synthesized the specific face images in people's advanced behaviors, solved the technical problems of expression synthesis and lip motion synthesis, and is studying the synchronization of gestures, head movements, pronunciation and intonation when people speak.
8. Learning summary and experience
Virtual reality technology is a research project with great potential and one of the important technologies in the future. It depends on many technologies in the fields of theory, software and hardware. Of course, many of them have only realized the theory, and the hardware needs to be improved. However, it can be seen that virtual reality technology will be widely used in the future.
This paper introduces the concept, characteristics, application scope, related technologies, equipment involved, difficulties in technical realization and research status in various countries. Most importantly, through the study of this technical project, we learned more knowledge about computers and more knowledge about hardware devices between computers, which aroused our strong interest in virtual reality technology. In the future, we will continue to pay attention to the development of virtual reality technology, and if there is an opportunity, we will definitely contribute to this technology.
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