An Introduction into the What's and How's of Virtual Reality
Virtual Reality (VR) was just a dream a few short years ago. Now integrating sound, vision and feel it is allowing us to design, repair and be entertained in a way that used to be science fiction. Virtual Reality is developing fast and we want to see the latest developments. By most, Virtual Reality or VR has been thought to be purely immersive reality, which is expensive simulation like the ones used for flight simulation and high priced gaming simulations. But in reality VR is all around us and many might not even know it. VR comes in all shapes and sizes. Your computer and you video games are tools to view VR. Yes even those simple games you play are a form of VR. The internet alone is one of the biggest sources of VR, full of VR malls (online malls, like ebay), 3D animations, even the pictures you see on the internet are all forms of VR.
Today, 'Virtual Reality' is used in a variety of ways and often in a confusing and misleading manner. Originally, the term referred to 'Immersive Virtual Reality.' In immersive VR, the user becomes fully immersed in an artificial, three-dimensional world that is completely generated by a computer. By means of special VR equipment which sre explained in detail below. But there is also non-immersive VR like VRML which will also be presented later on in this review. Listed below with descriptions are the equipment for viewing immersed reality.
The head-mounted display (HMD) was the first device providing its wearer with an immersive experience. Evans and Sutherland demonstrated a head-mounted stereo display already in 1965. In 1989 the EyePhone from VPL Research was the first commercially available HMD.
A typical HMD houses two miniature display screens and an optical system that channels the images from the screens to the eyes, thereby, presenting a stereo view of a virtual world. A motion tracker continuously measures the position and orientation of the user's head and allows the image-generating computer to adjust the scene representation to the current view. As a result, the viewer can look around and walk through the surrounding virtual environment. To overcome the often uncomfortable intrusiveness of a head-mounted display, alternative concepts like BOOM and
CAVE, for immersive viewing of virtual environments were developed.
The BOOM (Binocular Omni-Orientation Monitor) from Fakespace is a head-coupled stereoscopic display device. Screens and optical system are housed in a box that is attached to a multi-link arm. The user looks into the box through two holes, sees the virtual world, and can guide the box to any position within the operational volume of the device. Head tracking is accomplished via sensors in the links of the arm that holds the box.
The CAVE (Cave Automatic Virtual Environment) was developed at the University of Illinois at Chicago and provides the illusion of immersion by projecting stereo images on the walls and floor of a room-sized cube. Several persons wearing lightweight stereo glasses can enter and walk freely inside the CAVE. A head tracking system continuously adjust the stereo projection to the current position of the leading viewer.
A variety of input devices like data gloves, joysticks, and hand-held wands allow the user to navigate through a virtual environment and to interact with virtual objects. Directional sound, tactile and force feedback devices, voice recognition and other technologies are being employed to enrich the immersive experience and to create more "sensualized" interfaces.
The unique characteristics of immersive virtual reality can be summarized as follows:
Head-referenced viewing provides a natural interface for the navigation in three-dimensional space and allows for
· Look-around, walk-around, and fly-through capabilities in virtual environments.
· Stereoscopic viewing enhances the perception of depth and the sense of space.
· The virtual world is presented in full scale and relates properly to the human size.
· Realistic interactions with virtual objects via data glove and similar devices allow for manipulation, operation, and control of virtual worlds.
The convincing illusion of being fully immersed in an artificial world can be enhanced by auditory, haptic, and other non-visual technologies. Networked applications allow for shared virtual environments, as presented below.
In the example illustrated below, three networked users at different locations (anywhere in the world) meet in the same virtual world by using a BOOM device, a CAVE system, and a Head-Mounted Display, respectively. All users see the same virtual environment from their respective points of view. Each user is presented as a virtual human (avatar) to the other participants. The users can see each other, communicated with each other, and interact with the virtual world as a team.
Today, the term 'Virtual Reality' is also used for applications that are not fully immersive. The boundaries are becoming blurred, but all variations of VR will be important in the future. This includes mouse-controlled navigation through a three-dimensional environment on a graphics monitor, stereo viewing from the monitor via stereo glasses, stereo projection systems, and others. Apple's QuickTime VR, for example, uses photographs for the modeling of three-dimensional worlds and provides pseudo look-around and walk-trough capabilities on a graphics monitor.
Most exciting is the ongoing development of VRML (Virtual Reality Modeling Language) on the World Wide Web. In addition to HTML, that has become a standard authoring tool for the creation of home pages, VRML provides three-dimensional worlds with integrated hyperlinks on the Web. Home pages become home spaces. The viewing of VRML models via a VRML plug-in for Web browsers is usually done on a graphics monitor under mouse-control and, therefore, not fully immersive. However, the syntax and data structure of VRML provide an excellent tool for the modeling of three-dimensional worlds that are functional and interactive and that can, ultimately, be transferred into fully immersive viewing systems. The current version VRML 2.0 has become an international ISO/IEC standard under the name VRML97.
Today besides completely immersing someone into an artificial world, other VR-related technologies combine virtual and real environments. Motion trackers are employed to monitor the movements of dancers or athletes for subsequent studies in immersive VR. The technologies of 'Augmented Reality' allow for the viewing of real environments with superimposed virtual objects. Telepresence systems like telemedicine, telerobotics, immerse a viewer in a real world that is captured by video cameras at a distant location and allow for the remote manipulation of real objects via robot arms and manipulators.
As the technologies of virtual reality evolve, the applications of VR become literally unlimited. It is assumed that VR will reshape the interface between people and information technology by offering new ways for the communication of information, the visualization of processes, and the creative expression of ideas.
A virtual environment can represent any three-dimensional world that is either real or abstract. This includes real systems like buildings, landscapes, underwater shipwrecks, spacecrafts, archaeological excavation sites, human anatomy, sculptures, crime scene reconstructions, solar systems, and so on. Of special interest is the visual and sensual representation of abstract systems like magnetic fields, turbulent flow structures, molecular models, mathematical systems, auditorium acoustics, stock market behavior, population densities, information flows, and any other conceivable system including artistic and creative work of abstract nature. These virtual worlds can be animated, interactive, shared, and can expose behavior and functionality.
Useful applications of VR include training in a variety of areas (military, medical, equipment operation, etc.), education, design evaluation (virtual prototyping), architectural walk-through, human factors and ergonomic studies, simulation of assembly sequences and maintenance tasks, assistance for the handicapped, study and treatment of phobias like fear of height, entertainment, and much more.