Virtual reality sets are a means through which human beings attempt to establish a sense of presence in either a virtual world or the real world at a different location. They differ from each other in the way the user interfaces with the technology. Window on world (Wow) systems, mixed reality systems, and immersion virtual reality sets are three broad categories of virtual reality sets. Video mapping and telepresence-based systems are also different types of virtual reality sets.
Wow systems are also known as desktop virtual reality, and they use monitors to display the virtual world. The screen is a window to the world, and designers try to make it as realistic as possible. Users may use specially designed input devices to interact with the virtual world that the computer monitor displays. Ivan Sutherland influenced this area of virtual reality greatly when he published a paper called "The Ultimate Display" in 1965. A variation on Wow puts in a virtual actor that the user controls in the two-dimensional world, called video mapping, and medical professionals use this approach in surgical simulation applications.
Another approach, called telepresence, attempts to link the user's senses with remote sensors on tools or robots. Remotely controlled drones, unmanned aerial vehicles, and robots are useful in a variety of fields. Search and rescue operations, deep sea exploration, and medical operations are a few of the places where humans use these devices to safely interact with the real world. Some systems also incorporate haptic technologies to allow the user to feel pressure and other sensations, which come in very useful in specific applications like remotely controlled robotic surgery.
Immersion systems are very interesting types of virtual reality sets, where the user is totally immersed within a virtual world. They range from head-mounted displays to cave installations and differ in how deeply they try to immerse the user. Head-mounted displays have tethered or free-ranging helmets or face masks that transmit audio and video signals. They allow the user to move around in the real world and can be very inexpensive.
Cave installations, on the other hand, try to create the feeling of the virtual world within an enclosed space. They use huge projected displays and allow real-world objects to be mixed with virtual reality objects. A single user or multiple users can be immersed in a cave installation, which has high-resolution graphics that cover the walls, ceiling, and floor. The holodeck featured in the television series Star Trek: The Next Generation is a very advanced example of the this type of immersion virtual reality set.
Augmented reality or mixed reality systems combine telepresence with virtual reality sets to give users a seamless experience of the computer-generated world. The telepresence inputs are merged with data generated by the computer, and this is utilized in a variety of applications. The viewpoint of Arnold Schwarzenegger's character in the movie The Terminator is a classic example. The image seen by the user is overlaid or augmented with data feeds from a computer on transparent displays. Pilots, for instance, may see maps and altitude information in their augmented reality helmets.