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ABSTRACT
Abstract Virtual Reality (VR), sometimes called Virtual Environments (VE) has drawn much attention in the last few years. Extensive media coverage causes this interest to grow rapidly. Very few people, however, really know what VR is, what its basic principles and its open problems are. In this paper a historical overview of virtual reality is presented, basic terminology and classes of VR systems are listed, followed by applications of this technology in science, work, and entertainment areas. An insightful study of typical VR systems is done. All components of VR application and interrelations between them are thoroughly examined: input devices, output devices and software. Additionally human factors and their implication on the design issues of VE are discussed. Finally, the future of VR is considered in two aspects: technological and social. New research directions, technological frontiers and potential applications are pointed out. The possible positive and negative influence of VR on life of average people is speculated.
CHAPTER 1 INTRODUCTION
1.1 HISTORY
Nowadays computer graphics is used in many domains of our life. At the end of the 20th century it is difficult to imagine an architect, engineer, or interior designer working without a graphics workstation. In the last years the stormy development of microprocessor technology brings faster and faster computers to the market. These machines are equipped with better and faster graphics boards and their prices fall down rapidly. It becomes possible even for an average user, to move into the world of computer graphics. This fascination with a new reality often starts with computer games and lasts forever. It allows to see the surrounding world in other dimension and to experience things that are not accessible in real life or even not yet created. Moreover, the world of three-dimensional graphics has neither borders nor constraints and can be created and manipulated by ourselves as we wish – we can enhance it by a fourth dimension: the dimension of our imagination…
But not enough: people always want more. They want to step into this world and interact with it
- instead of just watching a picture on the monitor. This technology which becomes overwhelmingly popular and fashionable in current decade is called Virtual Reality (VR). The very first idea of it was presented by Ivan Sutherland in 1965: “make that (virtual) world in the window look real, sound real, feel real, and respond realistically to the viewer’s actions” [Suth65]. It has been a long time since then, a lot of research has been done and status quo: “the Sutherland’s challenge of the Promised Land has not been reached yet but we are at least in sight of it” [Broo95].
Let us have a short glimpse at the last three decades of research in virtual reality and its highlights [Bala93a, Cruz93a, Giga93a, Holl95]:
- Sensorama – in years 1960-1962 Morton Heilig created a multi-sensory simulator. A prerecorded film in color and stereo, was augmented by binaural sound, scent, wind and vibration experiences. This was the first approach to create a virtual reality system and it had all the features of such an environment, but it was not interactive.(Fig.1)
simulator. The fighter pilot wore a HMD that augmented the out-thewindow view by the graphics describing targeting or optimal flight path information.
- VIVED – Virtual Visual Environment Display – constructed at the NASA Ames in 1984 with off-the-shelf technology a stereoscopic monochrome HMD.
- VPL – the VPL company manufactures the popular DataGlove (1985) and the Eyephone HMD (1988) – the first commercially available VR devices.
- BOOM – commercialized in 1989 by the Fake Space Labs. BOOM is a small box containing two CRT monitors that can be viewed through the eye holes. The user can grab the box, keep it by the eyes and move through the virtual world, as the mechanical arm measures the position and orientation of the box.
- UNC Walkthrough project – in the second half of 1980s at the University of North Carolina an architectural walkthrough application was developed. Several VR devices were constructed to improve the quality of this system like: HMDs, optical trackers and the Pixel-Plane graphics engine.
- Virtual Wind Tunnel – developed in early 1990s at the NASA Ames application that allowed the observation and investigation of flow-fields with the help of BOOM and Data Glove.
- CAVE – presented in 1992 CAVE (CAVE Automatic Virtual Environment) is a virtual reality and scientific visualization system. Instead of using a HMD it projects stereoscopic images on the walls of room (user must wear LCD shutter glasses). This approach assures superior quality and resolution of viewed images, and wider field of view in comparison to HMD based systems.
- Augmented Reality (AR) – a technology that “presents a virtual world that enriches, rather than replaces the real world” [Brys92c]. This is achieved by means of see-through HMD that superimposes virtual three-dimensional objects on real ones. This technology was previously used to enrich fighter pilot’s view with additional flight information (VCASS). Thanks to its great potential – the enhancement of human vision – augmented reality became a focus of many research projects in early 1990.
1.2. WHAT IS VR? WHAT IS VR NOT?
At the beginning of 1990s the development in the field of virtual reality became much more stormy and the term Virtual Reality itself became extremely popular. We can hear about Virtual Reality nearly in all sort of media, people use this term very often and they misuse it in many cases too. The reason is that this new, promising and fascinating technology captures greater interest of people than e.g., computer graphics. The consequence of this state is that nowadays the border between 3D computer graphics and Virtual Reality becomes fuzzy. Therefore in the following sections some definitions of Virtual Reality and its basic principles are presented.
1.2.1. SOME BASIC DEFINATIONS AND TERMINOLOGY
Virtual Reality (VR) and Virtual Environments (VE) are used in computer community interchangeably. These terms are the most popular and most often used, but there are many other. Just to mention a few most important ones: Synthetic Experience, Virtual Worlds, Artificial Worlds or Artificial Reality. All these names mean the same:
- “Real-time interactive graphics with three-dimensional models, combined with a display technology that gives the user the immersion in the model world and direct manipulation.” [Fuch92]
- “The illusion of participation in a synthetic environment rather than external observation of such an environment. VR relies on a three-dimensional, stereoscopic head-tracker displays, hand/body tracking and binaural sound. VR is an immersive, multi-sensory experience.” [Giga93a]
- “Computer simulations that use 3D graphics and devices such as the DataGlove to allow the user to interact with the simulation.” [Jarg95]
- “Virtual reality refers to immersive, interactive, multi-sensory, viewer-centered, three- dimensional computer generated environments and the combination of technologies required to build these environments.” [Cruz93a]
abstracted from the banks of every computer in human system” [Gibs83]. Today the term Cyberspace is rather associated with entertainment systems and World Wide Web (Internet).
1.3 TYPES OF VIRTUAL REALITY
There are five main types of Virtual Reality classified on the basis of Display Technology. These are as follows:
- Adventure games, MUD/MOO
Textually described virtual worlds where the user perceives the virtual environment through mental images based on the words read (like reading a novel).
- Desktop 3D
Virtual environment graphically displayed on a desktop computer monitor.
- Projected
3D environment projected onto a screen. It enables a single user to demonstrate concepts to a group of people. A CAVE(tm), where several screens are used to surround the user with images, is the most advanced form of projected VR in use today.
- Semi-immersive
Most advanced flight, ship and vehicle simulators are semi-immersive. The cockpit, bridge, or driving seat is a physical model, whereas the view of the world outside is computer-generated (typically projected).
- Immersive
It is the 3D environment seen through a head-mounted display (HMD). In a completely immersive system the user feels part of the environment (experiences a feeling of 'presence'). The user has no visual contact with the physical world.
CHAPTER 2
CONCEPTS OF VIRTUAL REALITY
BASIC PRINCIPLE
Virtual Reality (VR) is a fully-immersive, absorbing, interactive experience of an alternate reality through the use of a computer structure in which a person perceives a synthetic environment by means of special human-computer interface equipment and interacts with simulated objects in that environment as if they were real.
VR represents computer interface technology that is designed to leverage our natural human capabilities. Today's familiar interfaces - the keyboard, mouse, monitor, and GUI - force us to adapt to working within tight, unnatural, two-dimensional constraints. VR changes that. VR technologies let you interact with real-time 3D graphics in a more intuitive, natural manner. This approach enhances your ability to understand, analyze, create and communicate.
A VR system lets you experience data directly. For example, today's advanced interfaces let you look and move around inside a virtual model or environment, drive through it, lift items, hear things, feel things, and in other ways experience graphical objects and scenes much as you might experience objects and places in the physical world.
Fig.3 Components of VR
As a result, VR serves as a problem-solving tool that lets us accomplish what was previously impossible. It's also a communications medium, and, ultimately, an artistic tool/medium.
The current VRML specification is VRML97, which is an ISO and IEC standard. VRML97 is essentially the same as VRML 2.0, which in turn is essentially the SGI "Moving Worlds" proposal. VRML 1.0 is pretty much obsolete at this point, although most VRML 2.0 browsers will automatically convert VRML 1.0 worlds.
It's entirely possible to create VRML worlds with nothing more than the VRML specification, a text editor, and a VRML-enabled browser (all of which are free), if you're a programmer with a good grasp of 3D computer graphics concepts. On the other hand, a VRML modeling program can take a lot of the pain out of the process, and make 3D world creation accessible to non- technical designers.
2.2. HEAD MOUNTED DISPLAY
2.2.1. INTRODUCTION
A Head Mounted Display is just what it sounds like -- a computer display you wear on your head. Most HMDs are mounted in a helmet or a set of goggles. Engineers designed head- mounted displays to ensure that no matter in what direction a user might look, a monitor would stay in front of his eyes. Most HMDs have a screen for each eye, which gives the user the sense that the images he's looking at have depth.
Fig.4 HMD
The monitors in an HMD are most often Liquid Crystal Displays (LCD), though you might come across older models that use Cathode Ray Tube (CRT) displays. LCD monitors are more
compact, lightweight, efficient and inexpensive than CRT displays. The two major advantages CRT displays have over LCDs are screen resolution and brightness. Unfortunately, CRT displays are usually bulky and heavy. Almost every HMD using them is either uncomfortable to wear or requires a suspension mechanism to help offset the weight. Suspension mechanisms limit a user's movement, which in turn can impact his sense of immersion.
2.2.2. WORKING PRINCIPLE
HMD is an acronym for Head Mounted Display, which is a set of goggles or a helmet with tiny monitors in front of each eye that generates images seen by the wearer as being three dimensional. A true HMD includes a device for tracking the users head movements and orientation. In other words, it tracks what direction the user is looking. Most HMDs will track yaw, roll, and pitch and some will even track the users head translations, a full six degrees of freedom (6 DOF).
Many HMDs also have 3D sound headsets as part of the unit. Unconstrained objects have six different directions or rotations they are able to move within including forward or backwards, up or down, and left or right; these are called translations. Objects can also rotate around the principal axes.
2.3. DATA GLOVES
2.3.1. INTRODUCTION
A glove equipped with sensors that sense the movements of the hand and interfaces those movements with a computer. Data gloves are commonly used in virtual reality environments where the user sees an image of the data glove and can manipulate the movements of the virtual environment using the glove. It uses trackers and some form of bending sensors on each finger.
sight so that the cameras can "see" the dots to be triangulated into 3D spatial positions. The triangulation consists of correlating given points on two images.
2.4. HEAD TRACKER
2.4.1. WORKING PRINCIPLE
Head tracking is a precision, six degree-of-freedom positional and angular head tracking device. The first three "degrees of freedom" are coordinate movements along the X, Y, and Z axes. A mouse is a 2-D peripheral, detecting movement along two of the three axes previously mentioned. Head tracker detects movement in all three, as well as rotation on those axes.
Fig.6 Head Tracker
Head tracker can detect the movement of your head and translate that to computer control, For example "looking up, down, left, right" emulates the cursor control of your desktop mouse. Moving your head "toward the monitor or away from the monitor" is also detected and can be programmed to be computer control functions. Moving your head "up", "down", "left", or "right" are also detected and can become computer control functions.
2.5. I SMELLER
2.5.1. Working Principle
DigiScents has indexed thousands of smells based on their chemical structure and their place on the scent spectrum. Each scent is then coded and digitized into a small file. The digital file is embedded in Web content or e-mail. A user requests or triggers the file by clicking a mouse or opening an e-mail. A small amount of the aroma is emitted by the device in the direct vicinity of the user.
Fig.7 Smeller
The iSmell can create thousands of everyday scents with a small cartridge that contains 128 primary odors. These primary odors are mixed together to generate other smells that closely replicate common natural and manmade odors. The scent cartridge, like a printer's toner cartridge, will have to be replaced periodically to maintain the scent accuracy.
3.4. MOTION TRACKER
3.4.1. WORKING PRINCIPLE
- Mechanical:
Usually a mechanical arm attached to the tracked object.
Very accurate, short lag, but restrict movement.
- Electromagnetic:
Measures strength of magnetic fields in coils attached to objects.
3.1. INTRODUCTION
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.
Note that 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.
Fig.9 VR in Entertainment
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 (e.g., fear of height) • entertainment
Fig.10 Car learning stimulator
3.2. MEDICAL APPLICATIONS
In the past decade medical applications of virtual reality technology have been rapidly developing, and the technology has changed from a research curiosity to a commercially and clinically important area of medical informatics technology. Research and development activity is well summarized by the yearly "Medicine Meets Virtual Reality" meetings, and the commercialization of the technology is already at an advanced stage.
1.Diagnostics : Initially, algorithms for graphical rendering of anatomy have been used to provide support for three dimensional organ reconstructions from radiological cross sections. For the clinician this method of visualizations provided a more natural view of a patient's anatomy without losing the see through capability of the radiologist.
Fig.12 VR in Education
Systems based on virtual reality offer a unique opportunity for the training of professional surgical skills on a wide scale and in a repeatable manner, in a way similar to the routine training of pilots. Contrary to the preoperative planning systems, which require an extreme level of accurate registration and alignment of tissue (data fusion), medical and surgical education and training rely more on high fidelity visualization and realistic immersion into the virtual scene than on the precise data fusion of the applied models with the specific anatomy of a patient.
3.4. OTHER APPLICATION AREAS
Virtual reality offers promising solutions in many other areas of medical care, where the immersion into a virtual world can help the patient, the physician, and the developer of the technology. Several systems have been developed and tested for physical or mental rehabilitation and for supporting mental health therapy by exposing the patient to appropriate experience or illusion. Finally, virtual reality based technology plays a major role in telemedicine, ranging from remote diagnosis to complex teleinterventions.
Virtual reality based technology is a new but rapidly growing area in medicine, which will revolutionise health care in the foreseeable future. The impact of this technology is just beginning to be recognised owing to methodological, technical, and manufacturing breakthroughs in the past few years. It must, however, be emphasised that the technology is simply a tool and that the other critical areas of content development and physicianpatient relationship must be incorporated into the new systems.
3.5. COMMERCIAL APPLICATIONS
- Usage of Virtual Reality in medical field: Virtual reality based technology is a new but rapidly growing area in medicine, which will revolutionize health care in the foreseeable future. In the past decade medical applications of virtual reality technology had been rapidly developing, and the technology has changed from a research to a commercial. - Doctors getting trained in Virtual Hospitals: Education and training is one of the most promising application areas for virtual reality technologies. Medical students will be able to learn real world practical problem in VR world. For example Medical students can operate a patient who will be dieing due to a certain disease in a VR world and even medical students can get knowledge about emergencies an accident. - Image guided Diagnosis: Virtual Reality system will allow physicians to view data such as MRI(magnetic resonance imaging) scans during a surgery to aid in the proper positioning of medical instrumentation. - Aeronautical Training Programs: Virtual Reality is playing an important role in Aeronautics which is very helpful for Army, Air force, Navy etc. - Flight Stimulators: With the help of flight stimulators which are based on virtual reality we can train the pilots. - Virtual Reality Parachute Training: Virtual Reality Programs are also used in parachute training and it is only due this technology that life risk can be totally avoided. - Aircraft Designing Programs: Virtual Reality has done the job easy for the aircraft designers. They can easily check angle and the flow of air on the body of the aircraft. - World Tour: You can explore the every corner of the world with the help of virtual reality technology. Just imagine for a moment that you are sitting in your house located in Jaipur and you are enjoying visit to New York and if you do not like it then in less than a second approximately with a speed of light you can go to Dubai and if in Dubai there is a hot sunny day of June then you can enjoy snow fall just with a click of a button.
