Virtual reality technology is a computer simulation system that can create and experience a virtual world. It uses a computer to generate a simulation environment. It is a multi-source information fusion interactive system simulation of three-dimensional dynamic vision and physical behavior to immerse users in the system. Environment.
IntroductionVirtual reality technology is an important direction of simulation technology. The combination of simulation technology and computer graphics human-machine interface technology multimedia technology sensor technology network technology is a challenging cross-cutting discipline and research field. Virtual reality technology (VR) mainly includes simulation environment, perception, natural skills and sensing equipment. The simulation environment is a computer-generated, real-time, dynamic, three-dimensional, realistic image. Perception means that the ideal VR should have the perception that everyone has. In addition to the visual perception generated by computer graphics technology, there are also perceptions such as hearing, touch, force, and motion, and even olfactory and taste, also known as multi-perception. Natural skills refer to the rotation of the person's head, eyes, gestures, or other human behaviors. The computer processes the data that is appropriate to the actions of the participants, responds to the user's input in real time, and feeds back to the user's facial features. . A sensing device is a three-dimensional interactive device.
Development HistoryThe evolution of virtual reality technology can be divided into four stages. The simulation of voice-like dynamics is the first stage of implication of virtual reality. (1963) The virtual reality sprouted into the second stage (1963-1972). And the theory is initially formed into the third stage (1973-1989). The virtual reality theory is further improved and applied as the fourth stage (1990-2004).
featureMulti-perception
In addition to the visual perception of a general computer, there are also auditory perception, tactile perception, motion perception, and even taste, smell, and perception. The ideal virtual reality should have the perceptual function that everyone has.
Sense of virtual reality
Refers to the user's perception that the protagonist is present in the simulated environment. The ideal simulation environment should be such that it is difficult for users to distinguish between true and false.
Virtual reality interactivity
Refers to the user's degree of operability of objects within the simulated environment and the degree of natural feedback from the environment.
Virtual reality autonomy
Refers to the extent to which objects in a virtual environment act according to the laws of physical motion of the real world.
Key technology
Virtual reality is a combination of multiple technologies, including real-time 3D computer graphics technology, wide-angle (wide-view) stereo display technology, tracking technology for observers' heads, eyes and hands, as well as tactile/force feedback, stereo, network transmission, voice Input and output technology, etc. These techniques are described separately below.
Real-time 3D computer graphics
In contrast, using computer models to generate graphical images is not too difficult. If there are enough accurate models 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 flight simulation systems, image refreshing is important, and image quality requirements are high. Coupled with very complex virtual environments, the problem becomes quite difficult.
Virtual reality display
When people look at the world around them, because the positions of the two eyes are different, the images obtained are slightly different. These images are merged in the brain to form a whole picture about the surrounding world. This scene includes information about the distance. . 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 the like.
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 odd frames, the other eye can only see even frames, and the difference between odd and even frames is parallax. It produces a three-dimensional feeling.
Tracking of the user (head, eye): 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 that the user sees is determined by the location of the user and the direction of the head (eye).
Virtual reality headgear for tracking head movement: In traditional computer graphics technology, the change of field of view is realized by mouse or keyboard, the user's visual system and motion perception system are separated, and the head tracking is used to change the image. The perspective between the user's visual system and the motion perception system can be linked and feels more realistic. Another advantage is that the user can not only recognize the environment through binocular stereo vision, but also observe the environment through the movement of the head.
Keyboard and mouse are the most commonly used tools in user interaction with computers, but they are not suitable for 3D space. Because of the six degrees of freedom in three-dimensional space, it is difficult to find a more intuitive way to map the planar motion of the mouse into any motion in three dimensions. Now, there are already some devices that offer six degrees of freedom, such as the 3Space digitizer and the SpaceBall space ball. Other devices with superior performance are data gloves and data clothing.
Virtual reality sound
People can well determine the direction of the sound source. In the horizontal direction, we determine the direction of the sound by the difference in phase and intensity of the sound, because the time or distance at which the sound reaches the two ears is different. The common stereo effect is achieved by hearing the different sounds recorded at different locations on the left and right ears, so there is a sense of direction. In real life, when the head turns, the direction of the sound heard changes. However, in the current VR system, the direction of the sound is independent of the movement of the user's head.
Virtual reality sensory feedback
In a VR system, the user can see a virtual cup. You can try to catch it, but your hand doesn't really touch the cup and it's possible to cross the "surface" of the virtual cup, which is impossible in real life. A common device for solving this problem is to mount some vibrating contacts on the inner layer of the glove to simulate the sense of touch.
Virtual reality speech
In VR systems, the input and output of speech is also important. This requires the virtual environment to understand the 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 "multilateralism" and complexity. For example, there is no obvious pause between words and words in continuous speech. The pronunciation of the same word and the same word is affected by the words and words before and after. Not only different people say that the same word will be different, that is, the same person’s pronunciation will also be psychologically Physiological and environmental effects vary.
There are two problems with the use of human natural language as a computer input. The first is efficiency. To facilitate computer understanding, the input speech may be quite embarrassing. The second is the question of correctness. The way computers understand speech is to compare and match, and no one is intelligent.
Technical characteristics
VR art is a new and independent art category that comes with the advent of the "virtual reality era." In the article "Virtual Reality Art: The Metaphysical Ultimate Re-creation", the VR art has the following definition: The art form of artificial intelligence technology such as virtual reality (VR) and augmented reality (AR) is used as a media means. We call it virtual reality art, referred to as VR art. The main features of this art form are hypertextuality and interactivity. â€
"As a comprehensive manifestation of the frontier of modern science and technology, VR art is a new form of artistic language that visualizes and interacts with complex data through human-machine interface. The important thing that attracts artists is the close integration of artistic thinking and technological tools. And the new cognitive experience created by the deep penetration of the two. Compared with the new media art under the traditional window operation, the interactive and extended human-machine dialogue is the key to the unique advantages of VR art. It is said that VR art is an interactive art form based on new human-machine dialogue. Its greatest advantage lies in constructing the dialogue between the works and the participants, and revealing the process of meaning generation through dialogue.
Through the application of VR, AR and other technologies, the artist can use more natural human-computer interaction means to control the form of the work, to create a more immersive artistic environment and the dream that cannot be realized under the reality, and to give the creation process New meaning. For example, the interactive device system with VR nature can set the audience to cross the multi-sensory interaction channel and the process of crossing the device. The artist can use the smooth cooperation of software and hardware to promote communication and feedback between the participants and the works, and create good participation. And maneuverability; motion capture through the video interface, store the visitor's behavioral segments, based on the participants' awareness-enhancing, synchronized screening enhancements and re-imaged, processed images; through augmented reality, blending Reality and other forms, combining the digital world and the real world, the audience can control the projected text through their own actions, such as data gloves can provide force feedback, movable scenes, 360-degree rotating sphere space not only enhance the immersion of the work Sense, and can allow the audience to enter the interior of the work, manipulate it, observe its process, and even give the audience the opportunity to participate in re-creation. â€
Virtual reality technology application
Virtual reality medicine
The application of VR in medicine has very important practical significance. In the virtual environment, a virtual human body model can be established. With the help of trackballs, HMDs, and sensation gloves, students can easily understand the structure of various organs inside the human body, which is much more effective than the existing method of using textbooks. In the early 1990s, researchers such as Pieper and Satara built a virtual surgical trainer based on two SGI workstations for leg and abdominal surgery simulations. This virtual environment includes virtual operating tables and surgical lights, virtual surgical tools (such as scalpels, syringes, surgical forceps, etc.), virtual mannequins and organs. With HMD and sensation gloves, the user can perform surgery on a virtual mannequin. However, the system needs to be further improved. If you need to improve the realism of the environment, increase the network function, so that it can train multiple users at the same time, or work under the guidance of foreign experts. VR technology is of great significance in predicting the outcome of surgery and improving the condition of people with disabilities, as well as the development of new drugs.
In medical colleges, students can perform “corpse†anatomy and various surgical exercises in a virtual laboratory. With this technology, training costs are greatly reduced because they are not subject to restrictions on specimens and venues. Some virtual reality systems for medical training, internships and research have a very high degree of simulation, and their superiority and effect are immeasurable and incomparable. For example, a catheter-inserted artery simulator allows the student to repeatedly practice the insertion of the catheter into the artery; the eye surgery simulator creates a three-dimensional image based on the anterior eye structure of the human eye with real-time tactile feedback that the student uses. The whole process of mimicking the removal of the lens can be observed, and the blood vessels, the iris and scleral tissues of the anterior structure of the eye, and the transparency of the cornea can be observed. There are also anesthesia virtual reality systems, oral surgery simulators, and the like.
Surgeons can use the help of virtual reality technology to repeatedly simulate surgery on the display, move organs in the body, find the best surgical plan and improve proficiency. Virtual reality technology can play a very important role in remote remote surgery, planning of complex surgery, information guidance of surgical procedures, prediction of surgical outcomes and improvement of living conditions of disabled people, and even new drug development.
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