Virtual Reality System (Virtual Reality System, referred to as VR; also translated as Lingjing, Huanzhen) is a high-tech in the field of graphics and images that has emerged in recent years, and is also known as Lingjing technology or artificial environment. Virtual reality is the use of computer simulation to generate a three-dimensional virtual world, providing users with the simulation of vision, hearing, touch and other senses, allowing users to observe the three-dimensional space in time and without restrictions thing. In addition, a virtual reality system is also called a virtual reality platform, namely (Virtual Reality Platform, VR-Platform or VRP for short).
VR is a comprehensive integrated technology, involving computer graphics, human-computer interaction technology, sensing technology, artificial intelligence and other fields. It uses computers to generate realistic three-dimensional visual, auditory, smell and other sensations, allowing people as participants to pass appropriate devices , Naturally experience and interact with the virtual world. When the user moves the position, the computer can immediately perform complex calculations to return accurate 3D world images to produce a sense of presence. This technology integrates the latest developments in computer graphics (CG) technology, computer simulation technology, artificial intelligence, sensor technology, display technology, network parallel processing, etc. It is a high-tech simulation system assisted by computer technology.
In a nutshell, virtual reality is a new way for people to visualize and interact with complex data through computers. Compared with traditional man-machine interfaces and popular window operations, virtual reality has a qualitative leap in technical thinking.
The "reality" in virtual reality generally refers to any thing or environment that exists in the world in a physical or functional sense. It can be actually achievable, or it can be practically difficult or impossible to achieve. . And "virtual" refers to the meaning of computer generated. Therefore, virtual reality refers to a special environment generated by a computer. People can "project" themselves into this environment by using various special devices, and operate and control the environment to achieve special purposes, that is, people are this environment. Dominate.
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 observer’s head, eyes and hands, as well as tactile/force feedback, stereo, network transmission, and voice Input and output technology, etc.:
1. Real-time 3D computer graphics technology
. In comparison, it is not too difficult to use computer models to generate graphics images. 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 the requirements for image quality are also very high. Coupled with a very complex virtual environment, the problem becomes quite difficult.
Second, the wide-angle (wide field of view) stereoscopic display When
people look at the surrounding world, the images obtained are slightly different due to the different positions of the two eyes. These images are merged in the brain to form an overall view of the surrounding world , This scene includes distance information. Of course, the distance information can also be obtained by other methods, such as the distance of the eye focal length, the comparison of the object size, and so on.
In the VR system, binocular stereo vision plays a big role. The 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 the odd-numbered frames, and the other eye can only see the even-numbered frames. The difference between odd and even frames is the parallax It has a three-dimensional effect.
In the interaction between the user and the computer, the keyboard and mouse are currently the most commonly used tools, but they are not suitable for three-dimensional space. Because there are six degrees of freedom in the three-dimensional space, it is difficult for us to find a more intuitive way to map the flat motion of the mouse to any motion in the three-dimensional space. There are already some devices that can provide six degrees of freedom, such as 3Space digitizer and SpaceBall space ball. Other devices with excellent performance are data gloves and data suits.
Three, stereo
People can determine the direction of the sound source well. In the horizontal direction, we rely on the phase difference and the intensity of the sound to determine the direction of the sound, because the time or distance of the sound to the two ears is different. Common stereo effects are achieved by hearing different sounds recorded in different positions in the left and right ears, so there is a sense of direction. In real life, when the head is turned, the direction of the sound heard will change. In a VR system, the direction of sound has nothing to do with the movement of the user's head.
Fourth, tactile and force feedback
In a VR system, the user can see a virtual cup. You can try to grab it, but your hand does not really touch the cup, and it 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 the sense of touch.
V. Voice input and output
In VR systems, voice input and output are also very important. This requires the virtual environment to understand people's 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 character is affected by the words and characters before and after it. Not only will different people say the same word differently, but the pronunciation of the same person will also be affected by psychological and psychological problems. Physiological and environmental influences vary.
There are currently two problems with using human natural language as computer input. The first is efficiency. In order to facilitate computer understanding, the input voice may be quite verbose. The second is the question of correctness. The computer's way to understand speech is to compare and match, and there is no human intelligence.
The characteristics of virtual reality technology and the key technology of the system
. Virtual reality is essentially an advanced computer user interface. It provides users with various intuitive and natural real-time perception and interaction methods such as sight, hearing, and touch. , To maximize the convenience of user operations, thereby reducing the burden on users and improving the efficiency of the entire system. Therefore, virtual reality technology has the following four important characteristics.
(1) Multi-sensitivity The
so-called multi-sensitivity means that guidance includes not only visual perception, but also hearing, force, touch and movement perception, and even taste perception and smell perception.
(2) Sense of Existence
Also known as the sense of presence, it refers to the real degree that users feel as the protagonist in the simulated environment. The ideal simulation environment should reach the level that makes it difficult for users to distinguish true from false.
(3) Interactivity
It refers to the user's degree of maneuverability of objects in the simulated environment and the natural degree of feedback from the environment (including real-time). We use our 8 sense organs to experience the real environment in a virtual environment.
(4) Autonomy
refers to the degree to which objects in the virtual environment act 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. Among them, the purpose of 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 a corresponding virtual environment model. The key to the generation technology of 3D graphics is how to achieve "real-time" generation. Stereoscopic display and sensor technology are the key to implementing interactive capabilities in virtual reality.