VR (Virtual Reality, referred to as VR) 1. Definitions and Interpretation: Simply put, virtual reality is the use of computer simulation of realistic scenes, so that the participants get the same feeling and the reality. The most significant point is that it is generated by the computer. In summary, the use of computer simulation to generate a three-dimensional virtual world, providing the user to simulate visual, auditory, tactile and other sensory, allowing users as immersive general, can be in time and no limitation to observe things in three-dimension. VR is a comprehensive integrated technology involving computer graphics, human-computer interaction technology, sensor technology, artificial intelligence and other fields. It uses computer-generated realistic three-dimensional vision, hearing, smell and feeling, making a man as participant, through appropriate device, feel naturally in the virtual reality world experience and interaction. When the user moves position, the computer can perform complex operations immediately, and send accurate 3D images back to produce presence. The technology integrates computer graphics (CG) technology, computer simulation technology, artificial intelligence, sensor technology, display technology, the latest development of network technologies such as parallel processing etc, is a computer-aided generation of high-tech simulation system. 2.The basic characteristics of virtual reality 1) Multi-Sensory The so-called multi-sensing means in addition to the visual percepton of the general computer, there are auditory perception, haptic perception, tactile perception, motion perception, and even taste perception, olfactory perception etc. Ideal virtual reality technology should have all the sensing functions of people. In general, a complete virtual reality system by the virtual environment to high-performance computers as the core processor virtual environment to HMD as the core of the visual system, voice recognition, voice synthesis and sound localization at the core of the auditory system, azimuth tracking, data gloves and clothing as the main body of data bearing attitude tracking equipment, as well as taste, smell, touch and haptic feedback system functions such units. 2)Immersion Also known as telepresence, it refers to the user feel as the lead present in the simulated environment of the true extent. Ideal simulation environment should make it difficult for users to distinguish between true and false, allowing users to dedicate themselves to the three-dimensional virtual environment created on a computer, everything in the environment appears to be true, it sounds really, really moving, even smells, tastes, etc. All are feeling really feel like in the real world. 3) Interactivity It refers to the degree of user-operable objects within the simulation environment and the natural level (including real time) to get feedback from the environment. For example, users can just grab a hand to simulate the environment of virtual objects, then hand can feel holding something, and you can feel the weight of the object, the View object can be caught immediately with the movement of the hand . 4) Imagination Virtual reality technology has stressed should be broad imagination, broadening the scope of human cognition, not only can reproduce real environment, but also can take an objective idea that does not exist or is unlikely to occur in the environment. Since the first letter of a sense of immersion, interaction and imagination is "I", so these three characteristics is often referred to as 3I characteristics.