What is Virtual Reality?


Opinions are divided about the requirements a system must meet in order to qualify for the term "Virtual Reality System". The name tells us there should be a virtual reality. A reality that doesn't actually exist. But that is not enough; There are for example systems that use video cameras to give a user a sensation of being in a different location. In such cases, it is not presenting a reality that doesn't exist. It's just that the presented reality exists in a different location from the user.

A more general difinition therefore states that a VR-system presents the user a seeming reality. A reality that appears to exist to the user at that moment.

The most important aspects that play a role in VR are:

  • Are the presented images generated by a computer?

Systems exist where real images are presented in 3 dimensional viewing. The user gets the feeling of being present at the projected location. One application of this, in which interaction with the environment is possible, is remotely controlling robots in locations that are inaccessible or dangerous to humans One point of view is that such systems can't be classified as VR, because real images are used. Others state that the word 'virtual' stems from the term 'virtual image', which existed long before computers were invented. This term would apply to each image that appears to exist, including a mirror image. Others broaden the definition and find that everything that portrays an apparent reality can be classified as VR, including books and films.

  • Interaction

On this topic there is little disagreement; Most people would agree that interaction with the environment is an important criterion for a VR system. This means that books and films cannot be categorised as VR as they allow no interaction. Just as in true reality, the virtual system should respond immediately to actions from the user. The interaction may consist of navigation and/or of manipulation. 'Navigation' means that the user has the possibility to move in virtual surroundings. 'Manipulation' means that the user can influence objects in the virtual environment, for example by moving them.

  • Immersion

Immersion can be interpreted as the degree to which a user feels immersed in the virtual world. The greater the immersion, the more difficult it is for a user to distinguish the virtual world from the real world. Different definitions of VR attach different importance to this criterion. Some definitions say that immersion is an essential part of Virtual Reality, while others make a clear distinction between immersive and non-immersive Virtual Reality.

  • Stereoscopic display

This consideration is closely related to immersion. When using a stereoscopic display, the user is able to see the presented images in 3-D. This causes the images to seem more real, which means that there is a greater sense of immersion. Furthermore, a real 3-dimensional display (i.e. stereoscopic) leads to a better understanding of the presented data. In 3-D projection, people are much better able to estimate the proportions and positions of objects.

In summary, it can be stated that although the opinions about the exact definition of virtual reality diverge, elements such as interaction, immersion, and stereoscopic display play an important role. Also, the ability to generate the presented images with a computer, offers extensive possibilities. This page will therefore focus on virtual reality that features each of these four characteristics.

History of Virtual Reality

Virtual Reality is not something of the past few years. Since the 50's people have been toying with the idea of ​​an artificially created environment. In 1962 this idea was first put into practice using the Sensorama. This device was able to combine stereoscopic video images with movement, sound, smell and wind. In 1966 the successor of this device was completed. A user did not have to position himself in the unit, but the device was placed on the head of the user. The device made ​​use of two cathode ray tubes, it was the first head-mounted display (HMD). Due to the heavy weight of the cathode ray tubes at that time, the unit was attached to a mechanical arm, into which also various sensors were placed. By means of these sensors the orientation of the device could be determined. However, both devices made ​​use of pre-recorded video. With the advent of more powerful computers, it became possible to use computer generated images. In 1973 the first system was developed that could provide the HMD such images. This system was able to display simple scenes of about 200 to 400 polygons, with 20 frames per second. Around this time the U.S. government became very interested in the use of Virtual Reality for military applications and simulation applications. This resulted, inter alia, in a new version of the HMD in 1981. This model, developed by NASA, used LCD screens, making it portable by users without special construction. Around this time, Virtual Reality increasingly became the subject of science fiction novels and films, making the idea begin to live among the general public. Technical developments followed in quick succession so that the systems were able to generate more complex images. In the early 90s, several international conferences on Virtual Reality were held, which led to more attention for Virtual Reality within the scientific community. Virtual Reality systems have since then continued to develop, leading to a wide variety of devices and techniques.

Fields of application

The areas of application of Virtual Reality are very diverse. The number of applications has only increased in recent years. In the following paragraphs, a number of common applications are briefly discussed.


VR is widely used in the visualization of complex data and models. The added value of a three-dimensional view is that the models can be better understood that way. The picture on the left shows an impression of the appearance of a technical design (CAD) with a VR system. VR is also ideal for the visualization of abstract multidimensional datasets. Also, in chemistry, VR is frequently used for the presentation of complex molecular structures. The users can view these structures from all angles. In some applications these structures can be manipulated in a variety of ways.



VR offers people the opportunity to enter a non-existent location. This is particularly interesting in the field of architecture. With a VR system, people can walk around in a house that has not yet been built. This gives a much better impression of what one can expect than a scale model. VR is ideal for the presentation of a new building or even an entire neighborhood.


The computer games industry has experienced tremendous growth in recent years. Driven by rapid technological advances, computer games have become more realistic and more complex. VR provides a great addition to the game experience. Users can actually see the 3D images three-dimensionally. The game world is not located on a small screen in front of them, but all around them.


Virtual training is used in situations where actual training is expensive or offers too few options. A well-known example is a flight simulator. Pilots are trained without having to use a real airplane. They can practice actions and operations hands-on, without being in danger. This allows for a more effective training.


The number of medical applications of VR is rising sharply in recent years. VR can be used to train doctors. This enables them to practice certain interventions better than when using conventional training resources, such as dolls. VR can be a valuable addition during surgery. During surgery, a VR system can provide a doctor with important information, thanks to which he can perform the operation better.


Virtual Reality has everything to do with human senses. The purpose of a pure VR-system is to create a reality, where a user feels part of. VR is very interesting for artists because of this. It provides opportunities for the development of new, experimental forms of art.

Wouter Wognum (2008)