What Are the Different Types of Virtual Reality Systems?

Virtual Reality System (VR for short; also translated as spiritual realm, fantasy reality) is a high-tech in the field of graphic images that has appeared in recent years. It is also called spiritual realm technology or artificial environment. Virtual reality is the use of computer simulation to generate a three-dimensional space virtual world, which provides users with simulations of senses such as sight, hearing, and touch. It allows users to observe the three-dimensional space in a timely and unrestricted manner. thing. In addition, the virtual reality system is also called a virtual reality platform (Virtual Reality Platform, VR-Platform or VRP for short).

Virtual reality system

Virtual Reality System

VR is a comprehensive integration technology that involves

Generally speaking, a complete virtual reality system consists of a virtual environment, a virtual environment processor

These allow the operator to truly enter, interact with, and interact with a computer-generated interactive three-dimensional virtual environment. Through the interaction between participants and the simulation environment, and with the help of people's perception and cognition of the things they are in contact with, they help inspire participants' thinking and obtain a full range of spatial and logical information contained in the environment. The immersive immersion and the fun of human-computer interaction are the essential characteristics of virtual reality. The realistic conception of the space-time environment (that is, the process of inspiring thinking and obtaining information) is the ultimate goal of virtual reality.

Virtual reality is a combination of multiple technologies, including real-time 3D computer graphics technology, wide-angle (wide field of view) stereo display technology, tracking technology for the viewer's head, eyes, and hands, and tactile / force feedback, stereo, network transmission, voice Input and output technology, etc. Each of these technologies is explained below.

First, real-time three-dimensional computer graphics technology

Comparatively speaking, it is not too difficult to generate graphic images using computer models. If we have a sufficiently accurate model and enough time, we can generate accurate images of various objects under different lighting conditions, but the key here is real-time. For example, in a flight simulation system, image refresh is very important, and at the same time, the image quality is also very high. Coupled with a very complicated virtual environment, the problem becomes quite difficult.

Second, wide-angle (wide field of view) stereo display

When people look at the world around them, because the positions of their two eyes are different, the images they get are slightly different. These images are fused in their brains to form an overall picture of the surrounding world. This picture includes information about distance . Of course, the distance information can also be obtained by other methods, such as the distance of the focal length of the eye, the comparison of the object size, and so on.

In VR systems, binocular stereo vision plays a big role. Different images seen by the user's two eyes are generated separately and displayed on different displays. Some systems use a single display, but after the user wears special glasses, one eye can only see odd-numbered frames and the other eye can only see even-numbered frames. The difference between odd and even frames is parallax. A three-dimensional effect is created.

User (head, eye) tracking: In an artificial environment, each object has a position and attitude relative to the coordinate system of the system, and so does the user. The scene the user sees is determined by the user's position and head (eye) direction.

Virtual reality hood for tracking head movement: In traditional computer graphics technology, the field of view is changed by using the mouse or keyboard. The user's visual system and motion perception system are separated, and head tracking is used to change the image. Perspective, the user's visual system and motion perception system can be linked, and feel more realistic. Another advantage is that users can not only understand the environment through binocular stereo vision, but also observe the environment through the movement of the head.

Keyboard and mouse are currently the most commonly used tools in user-computer interaction, but they are not suitable for three-dimensional space. Because there are six degrees of freedom in three-dimensional space, it is difficult to find a more intuitive way to map the plane motion of the mouse into an arbitrary motion in three-dimensional space. There are already some devices that can provide six degrees of freedom, such as the 3Space digitizer and SpaceBall. Other devices with better performance are data gloves and data clothing.

Three, stereo

One can judge the direction of the sound source very well. In the horizontal direction, we rely on the phase difference and intensity difference of the sound to determine the direction of the sound, because the time or distance of the sound reaching the two ears is different. The common stereo effect is achieved by hearing different sounds recorded at different positions in the left and right ears, so there will be a sense of direction. In real life, when you turn your head, the direction of the sound you hear changes. In a VR system, the direction of the sound is independent of the movement of the user's head.

Fourth, tactile and force feedback

In a VR system, users can see a virtual cup. You can manage to grab it, but your hands don't really feel like touching the cup, and may pass through the "surface" of the virtual cup, which is impossible in real life. A common device to solve this problem is to install some vibrating contacts on the inner layer of the glove to simulate tactile sensation.

Five, voice input and output

In VR systems, voice input and output are also important. This requires that the virtual environment can understand human language and interact with people in real time. It is quite difficult for a computer to recognize human speech, because speech signals and natural language signals have their "multilaterality" and complexity. For example, there is no obvious pause between words in continuous speech. The pronunciation of the same word and the same word is affected by the words before and after. Physiological and environmental effects vary.

There are currently two problems with using human natural language as computer input. The first problem is efficiency. To facilitate computer understanding, the input speech may be quite verbose. The second is the question of correctness. The way a computer understands speech is contrast matching, without human intelligence.

Key Features of Virtual Reality Technology and Its System

In essence, virtual reality is an advanced computer user interface.It provides users with a variety of intuitive and natural real-time perceptual and interactive means such as viewing, listening, and touching to maximize the user's operation. Reduce the burden on users and improve the efficiency of the entire system. Therefore, virtual reality technology has the following four important characteristics.

(1) Multi-perception

The so-called multi-perception is that guidance includes not only visual perception, but also hearing, force, touch, and motion perception, and even taste perception and olfactory perception.

(2) Existence

Also known as telepresence, it refers to the degree of realism that the user feels as a protagonist in the simulated environment. The ideal simulation environment should be such that it is difficult for users to distinguish between true and false.

(Three) interactivity

It refers to the degree to which the user can manipulate the objects in the simulated environment and the natural degree of feedback (including real-time) from the environment. We use our 8 sense organs to experience the real environment in a virtual environment.

(IV) Autonomy

It refers to the degree to which objects in the virtual environment operate according to the laws of physics. The key technologies of the virtual reality system are mainly composed of five aspects: dynamic environment modeling technology, real-time 3D graphics generation technology, stereo display and sensor technology, application system development tools and system integration technology. The purpose of the dynamic environment modeling technology is to obtain three-dimensional data of the actual environment according to the needs of the application, and use the obtained three-dimensional data to establish the corresponding virtual environment model. The key to 3D graphics generation technology is how to achieve "real-time" generation. Stereoscopic display and sensor technology are the keys to implementing interactive capabilities in virtual reality.

Application of virtual reality technology

The application of virtual reality technology is extremely extensive. In 1993, Helsel and Doherty made statistics on 805 virtual reality research projects that have been carried out worldwide. The results show that the applications in entertainment, education and art occupy the mainstream, followed by the military. And aviation, medicine, business, in addition to visual computing, manufacturing and other aspects also have a considerable proportion. The following briefly introduces some of its applications.

(1) There are roughly two types of medical virtual reality applications. The first is the virtual human body, that is, the digital human body. Such a human body model doctor can more easily understand the structure and function of the human body. The other is a virtual surgery system that can be used to guide the operation.

(2) The rich sensory capabilities of entertainment, art, and education and the 3D display environment make virtual reality technology an ideal video game tool. Because the reality of VR is not too high in terms of entertainment, in recent years virtual reality technology has developed most rapidly in this respect. For example, Chicago (Chicago) opened the world's first large-scale virtual reality entertainment system that can be used by multiple people. Its theme is about a future war in 3025; the British developed a virtual reality game system called "Virtuality", The system won the annual virtual reality product award;

(3) Military and aerospace industry simulation and training has always been an important subject in the military and aerospace industry, which provides a broad application prospect for virtual reality technology. Using virtual reality technology to simulate the process of war has become the most advanced way to study war and train commanders. War laboratories can also play a huge role in testing predetermined plans for actual combat. Before the Gulf War began in 1991, the U.S. military entered various natural environments in the Gulf region and various data of the Iraqi army into the computer, and simulated various combat plans before finalizing the initial combat plan. Later developments in actual combat and simulation results were fairly consistent.

(4) Commercial virtual reality technology is often used for marketing. For example, when bidding for a construction project, the design scheme is expressed with virtual reality technology, which can bring the owner to visit the buildings of the future, such as the height of the door, the orientation of the window, the amount of light, and the interior decoration. It can also be used for tourist attractions and merchandising with many functions and various uses. Because using virtual reality technology to show the charm of such products is more attractive than using only text or pictures to promote.

(5) Scientific and technological development of virtual reality technology can shorten the development cycle and reduce costs. For example, at the beginning of 1998, Chrysler facilitated the use of virtual reality technology to make breakthroughs in the design of two new vehicles. For the first time, the designed new car was directly put into the production line from the computer screen, which means that the intermediate trial production was completely omitted. Thanks to the use of superior virtual reality technology, Chrysler avoided 1,500 design errors, saving 8 months of development time and $ 80 million in costs. Using virtual reality technology can also perform car crash tests, without having to use a real car to show the impact of the crash under different conditions.

Virtual reality technology has become the three major means for humans to explore the laws of the objective world together with theoretical analysis and scientific experiments. Using it to design new materials, you can understand in advance the effect of changing the composition on the properties of the material. Before the material is manufactured, you know how parts made from this material are damaged under different stress conditions.

The above only lists some application prospects of virtual reality technology. It is foreseeable that in the near future, virtual reality technology will affect or even change our concepts and habits, and will penetrate into people's daily work and life.

Further Prospects of Virtual Reality Technology

Virtual reality has come a long way from its infancy to its maturity today. Its research content involves many subject areas. We also recognize that technology in this field has great potential and broad application prospects.

Objectively speaking, the research content of virtual reality technology is only limited to the expansion of the computer's interface capabilities, and has just touched on the problem of human perception systems and the combination of muscle systems and computers. It has not even touched on "sensation information obtained by people in practice It is an important process of how to store and process in the human brain into the understanding of the objective world. " The barriers between people and information processing systems can be completely overcome only when the technical implementation of these problems is actually started to be involved. We look forward to the day when the virtual reality system becomes a powerful system for multi-dimensional information processing, a helper for people to think and create, and a powerful tool for deepening people's existing concepts and acquiring new ones.

We believe that with the rapid development of computer technology and network technology, computer 3D computing capabilities and network bandwidth have greatly increased, and the application of virtual reality in production and life will become increasingly widespread.

Virtual reality simulation

Physical blur

Physical blurring mainly includes key technologies such as basic model construction, spatial tracking, sound localization, visual tracking, and viewpoint sensing. These technologies make it possible to generate realistic virtual worlds, detect user operations in virtual environments, and obtain operational data.

(1) Basic model construction technology

The construction of the basic model is the basis of applying the computer technology to generate the virtual world. It reconstructs the real-world objects in the corresponding three-dimensional virtual world, and saves some physical properties according to the system requirements. The creation of the model of deep creative art is to first establish the geometric model of the object, determine its spatial position and geometric element attributes, and enhance the reality of the virtual environment through GIS data or remote sensing, and follow a certain movement and power in the virtual environment Learn the rules. When the geometric model and physical model are difficult to accurately describe some special objects or phenomena existing in the real world, some special model construction methods can be adopted according to specific needs.

(2) Space tracking technology

The spatial tracking of the virtual environment is mainly to determine the position and position of the user's head, hands, body or other manipulators in the three-dimensional virtual environment through space sensors on interactive devices such as helmet displays, data gloves, data glasses, and data clothes. direction. The tracking system generally consists of a transmitter, a receiver, and electronic components. There are several types of deep creative tracking systems: electromagnetic, mechanical, optical, and ultrasonic. Data gloves are commonly used human-machine interaction devices in VR systems. It can measure the position and shape of the hand to realize the virtual hand in the environment and its manipulation of virtual objects. Cyber Glove determines the position and orientation of hands and joints through the bending and twisting sensors on the fingers and the curvature and radian sensors on the palms.

(3) Sound tracking technology

Using the time difference, phase difference, sound pressure difference, etc. of the sound of different sound sources to reach a specific place to perform sound tracking of the virtual environment is an important part of Deep Creation to create physical blur for customers. Sound tracking generally includes several transmitters, receivers and control units. It can be connected to a helmet display, as well as other equipment such as data clothing, data gloves.

(4) Visual tracking and viewpoint sensing technology

The physical blur vision tracking technology uses the projection of the surrounding light or tracking light from the video camera to the XY plane array at different times and positions on the image projection plane to calculate the position and direction of the tracked object. The realization of visual tracking must consider the compromise between accuracy and operating range. The design of multiple transmitters and sensors can enhance the accuracy of visual tracking, but it makes the system complicated and expensive. Deep Creative's viewpoint sensing must be combined with display technology, using multiple positioning methods (eyecup positioning, helmet display, remote viewing technology and eye muscle-based sensing technology) to determine the user's line of sight at a certain moment. For example, integrating point-of-view detection and sensing technology into a helmet display system allows pilots to manipulate virtual switches or flight control in certain extraordinary periods by simply "gazing".

2. Materialization

The key technologies to ensure that users acquire sensory cognition such as vision, hearing, force, and touch in the virtual environment are the main research content of virtual reality.

(1) Visual perception

Most of the objects or phenomena with a certain shape in the virtual environment can make users have a strong visual perception through a variety of ways. CRT displays, large screen projections, multi-directional electronic walls, stereo glasses, and helmet displays (HMD) are common display devices in VR systems. Different helmet displays have different display technologies. Depending on how the optical image is provided, the helmet display device can be divided into a projection type and a direct view type. Stereoscopic display technology that can enhance the realism of the virtual environment can make users' left and right eyes see two plane images with parallax, and synthesize them in the brain to generate stereoscopic vision perception. Helmet displays and stereo glasses are two common stereo display devices. Deep Creation Technology is researching three-dimensional display technology based on laser holographic calculation and display technology that uses a laser beam to directly image on the retina.

(2) Auditory perception

Hearing is the second only way to perceive vision. The sound effects of the virtual environment can make up for the lack of visual effects and enhance the fidelity of the environment.

(3) Force and touch

One of the key factors that can make participants feel "immersive" is whether the user can feel the reaction force of the virtual object while manipulating the virtual object, thereby generating tactile and force perception. Because human force perception is very sensitive, general precision devices cannot meet the requirements at all, and it is quite difficult and expensive to develop high-precision force feedback devices, which is one of the problems people face. Without haptic feedback, it is easy for users to pass their hands through objects when they touch an object in the virtual world. An effective way to solve this problem is to add haptic feedback to the user's interactive device. Haptic feedback is mainly based on methods such as vision, barometric pressure, vibration touch, electronic touch, and neuromuscular simulation.

3. High-performance computing processing technology

Virtual reality is modern high-tech with computer technology as its core. High-performance computing and processing technology is the key to directly affecting system performance. High-performance computing processing technology with high computing speed, strong processing capacity, large storage capacity, and strong networking features is the main content of in-depth creative research.

4. Distributed Virtual Reality

The research goal of distributed virtual reality is to establish a distributed virtual environment where multiple users can participate in different places at the same time. Users in different geographical locations are as if entering a real world. They are not restricted by physical time and space. Communicate, study, discuss, train, entertain, and even collaborate on the same complex product design or perform the same difficult task. There are two camps for deep creative art distributed virtual reality research. One is distributed virtual reality on the Internet, such as remote virtual shopping based on the VRML standard. The other is in high-speed private networks invested by the military, such as the US military defense simulation Internet DSI using ATM technology.

At present, most of the means for realizing 3D virtual reality technology in China are secondary development using 3D graphics engines that are readily available abroad. More popular and relatively efficient 3D graphics engines are Vega, Vegaprim, Vtree, Virtools, Quest3D, etc. The Vega series of engines has too many design levels, which directly leads to the difficulty of the top-level system to directly and effectively play the characteristics of the hardware graphics device, and its operation becomes abnormally slow as the amount of data increases.

Application of simulation technology in the military and aerospace industry, urban planning and management, architectural design, real estate development, science and technology museums, museums, professional exhibition halls, product design and display, restoration and protection of ancient cultural heritage, simulation training equipment, games, entertainment And many other fields.

In addition, virtual reality technology has a wide range of applications in aerospace, communications, transportation, medical, education, art, sports, molecular chemistry, and scientific computing visualization. We can even boldly predict that in the near future, virtual reality technology will penetrate all disciplines and fields related to information systems.

Virtual reality technology and its development prospects

Virtual reality (VR) is one of the hotspots in the computer network world. It has very promising development prospects in many aspects of social life, and it is also the basis and basic technology for the concept of the digital earth.

Virtual reality is a three-dimensional environment simulated by a computer. It is a computer system that can create and experience a virtual world. The virtual environment is generated by a computer, and it acts on the user through human sight, hearing, and touch to make it a visual simulation of the immersive feeling. It is a comprehensive integrated technology involving computer, image processing and pattern recognition, speech and sound processing, artificial intelligence technology, sensing and measurement, simulation, microelectronics and other technologies. Users can enter this environment through a computer and can manipulate and interact with objects in the system. The real-time and interactive features in the three-dimensional environment are its main features.

Virtual reality is not real, nor is it, it is just a tool that can do interactive 3D graphical user interface on the desktop in real time. Just like window systems and mouse-driven user interfaces, virtual reality can make computers more efficient and transparent. According to the designer's idea, users can immerse themselves in the data space, isolate the user from the real environment for a certain period of time, and then invest in a virtual environment that can interact in real time, and control the data in it to make people have a presence Feeling.

The data interaction tool of the virtual reality interface is a developing technology. Its purpose is to make the information system meet human needs as much as possible. The human-computer interaction is more humanized, and users can interact with the data more directly. In addition to traditional monitors, keyboards, mice, and joysticks,

Instrumented gloves, Data Glove, and stereo polarized glasses are such products. Stereo vision products include head-mounted displays (HMD) and liquid crystal shutter glasses. According to reports, VR equipment in the research stage of the laboratory has immersive VR systems, adding interactive devices such as HMD, multiple large projection displays, and even adding touch, force, and contact feedback. Some people boldly predict that they will be full-body. The direction of data clothing.

The fields of application of virtual reality are very wide, mainly in engineering design, computer-aided design (CAD), data visualization, flight simulation, multimedia distance education, telemedicine, art creation, games, entertainment, etc.

With the advent of the Web, virtual reality technology has attracted widespread attention. People have high hopes for it, hoping to use this technology to enable people around the world to communicate in a three-dimensional environment. Multiple users can chat with text-based or sound technology, and building a true three-dimensional community on the Internet is no longer just a dream.

VRML is an object-oriented language. It is similar to the HTML language used by Web hyperlinks. It is also a text-based language. It can run on multiple platforms, but it can serve more virtual reality environments. It provides a description of the three-dimensional world and its basic objects, such as spheres, planes, cones, cylinders, cubes, etc., and links them to two-dimensional pages. It is a very simple high-level language. In addition to the latest VRML version 2.0, which provides the basic functions of VRML version 1.0, the most important feature is the addition of behavioral functions and a multi-user environment, making the three-dimensional world on the Web move. In addition, it will support animation, interactivity, integration with JAVAScript and JAVA, and sound. The emergence of VRML is due to the rapid development of contemporary network technology and virtual reality technology, which makes Web pages no longer limited to two-dimensional space. With VRML adding motion, animation simulation, sensors and sound, web site creators can make large-scale, interactive 3D applications.

The development prospect of virtual reality is very attractive, and the combination with the characteristics of network communication is what people dream of. In a sense, it will change the way people think, and even change people's views on the world, themselves, space and time. It is a developing new technology with far-reaching potential applications. Using it, we can build a real remote classroom in which we can study, discuss, and play with friends from all over the world, just like in real life. Using network computers and related three-dimensional equipment, our work, life, and entertainment will be more interesting. Because the digital earth brings us a gorgeous and colorful three-dimensional world!

Looking forward to the future is always exciting, and it will cause people to dream about dreams. The digital earth, like the dream, has the wings of science, which makes us feel that it is not out of reach, and even some of its prototypes have been applied to our real life.