Augmented Reality (AR) is a growing area in virtual reality research. The basic idea of augmented reality is to superimpose graphics, audio and other sense enhancements over a real-world environment in real-time.
Augmented reality (AR) refers to computer displays that add virtual information to a user's sensory perceptions. An augmented reality system generates a composite view for the user. It is a combination of the real scene viewed by the user and a virtual scene generated by the computer that augments the scene with additional information. Augmented reality research explores the application of computer-generated imagery in live-video streams as a way to expand the real-world. A typical example of augmented reality is a video of a car whose part names are displayed with graphical labels, overlaid onto the image in correct positions (as if hovering in mid-air). Advanced research includes use of head-mounted displays and virtual retinal displays for visualization purposes, and construction of controlled environments containing any number of sensors and actuators.
Although augmented reality may seem like the stuff of science fiction, researchers have been building prototype systems for more than three decades. In early 1990s that the term "augmented reality" was coined by scientists at Boeing who were developing an experimental AR system to help workers assemble wiring harnesses. The past decade has seen a flowering of AR research as hardware costs have fallen enough to make the necessary lab equipment affordable. Augmented reality is still in an early stage of research and development at various universities and high-tech companies.
Eventually, possibly by the end of this decade, we will see the first mass-marketed augmented-reality system, which one researcher calls "the Walkman of the 21st century." What augmented reality attempts to do is not only superimpose graphics over a real environment in real-time, but also change those graphics to accommodate a user's head- and eye- movements, so that the graphics always fit the perspective. The three components needed to make an augmented-reality system work:
The goal of augmented-reality developers is to incorporate these three components into one unit, housed in a belt-worn device that wirelessly relays information to a display that resembles an ordinary pair of eyeglasses .Virtual Reality: A computer generated, interactive, three-dimensional environment in which a person is immersed." -Jaron Lanier
What is meant by Augmented reality?
We believe that one of the most powerful uses of virtual worlds will not be to replace the real world, but rather to augment the user's view of the real world with additional information. This idea, introduced by Ivan Sutherland's pioneering work on head-mounted displays, is often referred to as augmented reality. It is necessary to make a useful distinction between the concept of real and the concept of virtual. The operational definitions that we adopt here are:
<1>Real objects are any objects that have an actual objective existence.
<2>Virtual objects are objects that exist in essence or effect, but not formally or actually.
Augmented Reality (AR) is essentially the fusion of real and virtual reality, where graphic objects are blended into real footage in real time. AR creates the illusion that virtual, computer-generated objects exist in the real world. Fundamentally, Augmented Reality is about augmentation of human perception: supplying information not ordinarily detectable by human senses. The augmented reality presented to the user enhances that person's performance in and perception of the world. AR experience is an experience of REALITY enhanced with VIRTUAL elements.
An augmented reality system generates a composite view for the user. It is a combination of the real scene viewed by the user and a virtual scene generated by the computer that augments the scene with additional information. Augmented reality (AR) is a term for a live direct or indirect view of a physical real-world environment whose elements are merged with-, or augmented by virtual computer-generated imagery - creating a mixed reality. The augmentation is conventionally in real-time and in semantic context with environmental elements, like for example sports scores on TV during a match.
For example, graphics and text overlaid on the surrounding world could explain how to operate, maintain, or repair equipment, without requiring that the user refer to a separate paper or electronic manual. Similarly, participants in a business meeting could interact with a dynamic shared financial or organizational model represented in 3D and selectively supplemented with each user's personal (and private) annotations. Generating such material by hand, however, will require a tremendous amount of expertise and effort, far greater than that currently needed to design ``hand-crafted'' hypermedia and multimedia presentations.
The ultimate goal is to create a system such that the user can not tell the difference between the real world and the virtual augmentation of it. To the user of this ultimate system it would appear that he is looking at a single real scene.
Picture yourself walking or driving down the street. With augmented-reality displays, which will eventually look much like a normal pair of glasses, informative graphics will appear in your field of view, and audio will coincide with whatever you see. These enhancements will be refreshed continually to reflect the movements of your head.
Augmented RealityVSVirtual Reality
Basically the difference between augmented reality and virtual reality can be described as follows:-
VIRTUAL REALITY: Replaces reality
AUGMENTED REALITY: Enhances reality
In Virtual Reality the basic idea is to immerse a user inside an imaginary, computer-generated "virtual world ".In its different technologies a common result is: the user is cut off from any view of the real world outside. Eg:- What will you feel!!! If you find your self near TAJ MAHAL though you are actually at some other place which is far away from TAJ MAHAL!!! Is this possible???!!! Yes. But how??? Of course by “VIRTUAL REALITY”.
Much less attention has been paid to the field of Augmented Reality, although its potential is at least as great as that of Virtual Reality. In Augmented Reality, the user can see the real world around him, with computer graphics superimposed or composited with the real world. Instead of replacing the real world, we supplement it. Ideally, it would seem to the user that the real and virtual objects coexisted. Virtual reality is a technology that encompasses a broad spectrum of ideas. It defines an umbrella under which many researchers and companies express their work.."A computer generated, interactive, three-dimensional environment in which a person is immersed." There are three key points in the definition.
<1> this virtual environment is a computer generated three-dimensional scene which requires high performance computer graphics to provide an adequate level of realism.
<2> the virtual world is interactive. A user requires real-time response from the system to be able to interact with it in an effective manner.
<3> the user is immersed in this virtual environment.
One of the identifying marks of a virtual reality system is the head mounted display worn by users. These displays block out all the external world and present to the viewer a view that is under the complete control of the computer. The user is completely immersed in an artificial world and becomes divorced from the real environment. For this immersion to appear realistic, the virtual reality system must accurately sense how the user is moving and determine what effect that will have on the scene being rendered in the head mounted display.
A very visible difference between these two types of systems is the immersiveness of the system. Virtual reality strives for a totally immersive environment. The visual, and in some systems aural and proprioceptive, senses are under control of the system. In contrast, an augmented reality system is augmenting the real world scene necessitating that the user maintains a sense of presence in that world. The virtual images are merged with the real view to create the augmented display. Mixed reality (MR) (encompassing both augmented reality and augmented virtuality) refers to the merging of real and virtual worlds to produce new environments and visualizations where physical and digital objects co-exist and interact in real time, A mix of reality, augmented reality, augmented virtuality and virtual reality.
Miligram's Reality-Virtuality Continuum
Miligram describes a taxonomy that identifies how augmented reality and virtual reality work are related. He defines the Reality-Virtuality continuum shown as Figure 1.
Figure 1 - Milgram's Reality-Virtuality Continuum
The real world and a totally virtual environment are at the two ends of this continuum with the middle region called Mixed Reality. Augmented reality lies near the real world end of the line with the predominate perception being the real world augmented by computer generated data. Augmented reality does not simply mean the superimposition of a graphic object over a real world scene. This is technically an easy task. One difficulty in augmenting reality, as defined here, is the need t006F maintain accurate registration of the virtual objects with the real world image.
As illustrated in Figure, Mixed Reality refers to the class of all displays in which there is some combination a real environment and Virtual Reality. Within this context, the meaning of the term Augmented Reality, depicted on the left half of the continuum, becomes quite clear: AR displays are those in which the image is of a primarily real environment, which is enhanced, or augmented, with computer-generated imagery. Using a see-through head-mounted display, for example, it is possible to make ghost-like images of anything we desire appear before the viewer in a fairly-well specified location in space. These images can display information, or can serve as interactive tools for measuring or controlling the environment.
A taxonomy for mixing real and virtual worlds .The first question to be answered in setting up the taxonomy is why the continuum presented in Fig.1 is not sufficient for our purposes as is, since it clearly defines the concept of AR displays and distinguishes these from the general class of AV displays, within the general framework of Mixed Reality. From the preceding section, however, it should be clear that, even though the RV continuum spans the space of MR options, its one dimensionality is too simple to highlight the various factors which distinguish one AR/AV system from another.
What is needed, rather, is to create a taxonomy with which the principal environment, or substrate, of different AR/AV systems can be depicted in terms of a (minimal) multidimensional hyperspace. Three (but not the only three) important properties of this hyperspace are evident from the discussion in this paper:
Reality; that is, some environments are primarily virtual, in the sense that they have been created artificially, by computer, while others are primarily real.
Immersion; that is, virtual and real environments can each be displayed without the need for the observer to be completely immersed within them.
Directness; that is, whether primary world objects are viewed directly or by means of some electronic synthesis process.
COMPONENTS OF A. R. SYSTEM
Head Mounted Displays
Monitor Based Displays
Tracking and Orientation
Mobile Computing Power
1. Head-mounted Displays:-
Just as monitors allow us to see text and graphics generated by computers, head-mounted displays (HMDs) will enable us to view graphics and text created by augmented-reality systems. So far, there haven't been many HMDs created specifically with augmented reality in mind. Most of the displays, which resemble some type of skiing goggles, were originally created for virtual reality.
There are two basic types of HMDS:
The "see-through" designation comes from the need for the user to be able to see the real world view that is immediately in front of him even when wearing the HMD. The standard HMD used in virtual reality work gives the user complete visual isolation from the surrounding environment. Since the display is visually isolating the system must use video cameras that are aligned with the display to obtain the view of the real world.