To create a virtual world, you need several technologies, each which have advanced separately. The basis of virtual reality is hardware, software, and electronics. These are the three computer- related technologies which are part of producing VR.
Audio, visual, and tactile are the three senses in the virtual environment which can be achieved by the use of input devices, such as gloves, tracking balls, bodysuits, or many other devices. VR experts are researching to find a way to also create the senses of taste and hot/cold in a virtual environment. When the user makes movements using the input devices, the computer then gives an output showing the user's interaction which is given to the user through glasses, head mounted display units, earphones and so on. These devices are under the category of electronics; each are emerging, so it's not just one technology or technique which is causing the development of VR.
All of the above techniques must be advanced enough to be able to converge with other techniques and be used meaningfully. They must be able to create a virtual environment which is thought to be real, allows interaction and responds quickly, and collects, perceives, and analyzes data. Computer generation of images is important to make a virtual environment seem real to the user. The speed of the machine is important because it has to be able to produce polygons, which make up mosaics to form the image. The computer must be quick enough to keep regenerating these polygons so that when the user interacts, and for instance, picks up an object, it's redrawn with polygons. Many computers have very good quality resolution, but they are not fast enough to keep up with the user's interaction, so latency occurs. Many computers are fast enough to be used for virtual reality, but their images are not as sharp as slow- moving ones.
The technique of using input devices must also be advanced to surround the user in sounds and images so that they forget they are in a virtual environment. Head mounted displays (HMD's) are the most complex of the devices. While working to develop an HMD, Ivan Sutherland had "no idea how much effort would be involved." HMD's originally used the cylindrical point of view. Here, the user can see the environment all around but cannot see a ceiling or a floor. But with advancements, VR experts have been able to create the spherical point of view. This is where a hemisphere or dome is used and the user can see all around except the floor. With more research, VR experts will hopefully create a point of view that is as close to reality as possible.