01-04-2010, 12:25 AM
ABSTRACT
Augmented reality (AR) refers to computer displays that add virtual information to a user's sensory perceptions. Most AR research focuses on "see-through" devices, usually worn on the head that overlay graphics and text on the user's view of his or her surroundings. AR systems track the position and orientation of the user's head so that the overlaid material can be aligned with the user's view of the world.
Consider what AR could make routinely possible. A repairperson viewing a broken piece of equipment could see instructions highlighting the parts that need to be inspected. A surgeon could get the equivalent of x-ray vision by observing live ultrasound scans of internal organs that are overlaid on the patient's body. Soldiers could see the positions of enemy snipers who had been spotted by unmanned reconnaissance planes.
Getting the right information at the right time and the right place is key in all these applications. Personal digital assistants such as the Palm and the Pocket PC can provide timely information using wireless networking and Global Positioning System (GPS) receivers that constantly track the handheld devices. But what makes augmented reality different is how the information is presented: not on a separate display but integrated with the user's perceptions. In augmented reality, the user's view of the world and the computer interface literally become one.
1.INTRODUCTION
INTRODUCTION
Video games have been entertaining us for nearly 30 years. Computer graphics have become much more sophisticated since then, and soon, game graphics will seem all too real. In the next decade, researchers plan to pull graphics out of your television screen or computer display and integrate them into real-world environments. This new technology, called augmented reality, will further blur the line between what's real and what's computer-generated by enhancing what we see, hear, feel and smell. The basic idea of augmented reality is to superimpose graphics, audio and other sense enhancements over a real-world environment in real-time. 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.
Walk down the street, look at the world. This is reality. Now repeat, but wearing an odd-looking, bulky pair of glasses that place into your line of vision selective, relevant bits of data about the world or informative graphics and produce sound which will coincide with whatever you see.. This is augmented reality. An AR system, can superimpose computer generated text, graghics,3-D animation, sound, or any other digitised data on the real world. The augmented reality systems employ a see-through head-worn display that overlays graphics and sound on a person's naturally occurring sight and hearing. By tracking users and objects in space, these systems provide users with visual information that is tied to the physical environment. It 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.
Augmented-reality displays will overlay
computer-generated graphics onto the real world.
On the spectrum between virtual reality, which creates immersible, computer-generated environments, and the real world, augmented reality is closer to the real world. Augmented reality adds graphics, sounds, hap tics and smell to the natural world as it exists. You can expect video games to drive the development of augmented reality, but this technology will have countless applications. Everyone from tourists to military troops will benefit from the ability to place computer-generated graphics in their field of vision.
Augmented reality will truly change the way we view the world. 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. In this article, we will take a look at this future technology, its components and how it will be used.
2. COMPARISON WITH VIRTUAL REALITY
COMPARISON WITH VIRTUAL REALITY
Augmented reality is very much close to virtual reality. Virtual reality is a technology that encompasses a broad spectrum of ideas. The term was defined as "a computer generated, interactive, three-dimensional environment in which a person is immersed." Virtual reality creates immersible, computer generated environments which replaces real world .Here the head mounted displays block out all the external world from the viewer and present a view that is under the complete control of the computer.
A very visible difference between the 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. There must be a mechanism to combine the real and virtual that is not present in other virtual reality work. Developing the technology for merging the real and virtual image streams is an active research topic
Augmented reality is closer to the real world. Augmented reality adds graphics, sounds, hap tics and smell to the natural world, as it exists. Thus it augments the real world scene in such a way that the user can maintain a sense of presence in that world. That is, the user can interact with the real world , and at the same time can see, both the real and virtual world co-existing. For the same reason it has a large number of applications in the day to day life as compared to virtual reality.
The computer generated virtual objects must be accurately registered with the real world in all dimensions. Errors in this registration will prevent the user from seeing the real and virtual images as fused. The correct registration must also be maintained while the user moves about within the real environment. Discrepancies or changes in the apparent registration will range from distracting which makes working with the augmented view more difficult, to physically disturbing for the user making the system completely unusable. An immersive virtual reality system must maintain registration so that changes in the rendered scene match with the perceptions of the user. Any errors here are conflicts between the visual system and the kinesthetic or proprioceptive systems.
Milgram (Milgram and Kishino 1994; Milgram, Takemura et al. 1994) describes a taxonomy that identifies how augmented reality and virtual reality work are related. He defines the Reality-Virtuality continuum shown as Figure 2.
Figure 2 - 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 virtuality is a term created by Milgram to identify systems which are mostly synthetic with some real world imagery added such as texture mapping video onto virtual objects. This is a distinction that will fade as the technology improves and the virtual elements in the scene become less distinguishable from the real ones.
3. EARLY DEVELOPMENT
EARLY DEVELOPMENT
The first AR system was developed in the 1960s by computer graphics pioneer Ivan Sutherland and his students at Harvard University and the University of Utah. In the 1970s and 1980s a small number of researchers studied augmented reality at institutions such as the U.S. Air Force's Armstrong Laboratory, the NASA Ames Research Center and the University of North Carolina at Chapel Hill. It wasn't until the 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. Scientists have gathered at yearly AR conferences since 1998. 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."
4.COMPONENTS OF AUGMENTED
REALITY SYSTEM
COMPONENTS OF AUGMENTED REALITY SYSTEM
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. Here are the three components needed to make an augmented-reality system work :
¢ Head mounted displays
¢ Tracking and orientation system
¢ Mobile computing power
Photo courtesy Columbia University Computer Graphics and User Interfaces Lab
Early prototype of a mobile augmented-reality system
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. Let's take a look at each of the components of this system.
4.1 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. These forms one of the main components of an augmented reality system. They are used to merge the virtual world and real world in front of the user in such a way that he feels he is looking at a single real scene . They resemble some type of skiing goggles.
There are two basic types of HMDS:
¢ video see-through
¢ optical see-through
VIDEO SEE- THROUGH
Video see-through displays block out the wearer's surrounding environment, using small video cameras attached to the outside of the goggles to capture images. On the inside of the display, the video image is played in real-time and the graphics are superimposed on the video. One problem with the use of video cameras is that there is more lag, meaning that there is a delay in image-adjustment when the viewer moves his or her head.
OPTICAL SEE-THROUGH
Optical see-through displays is not fully realized yet. It is supposed to consist of a ordinary-looking pair of glasses that will have a light source on the side to project images on to the retina.
COMPARISON
There are advantages and disadvantages to each of these types of displays. With both of the displays that use a video camera to view the real world there is a forced delay of up to one frame time to perform the video merging operation. At standard frame rates that will be potentially a 33.33 millisecond delay in the view seen by the user. Since everything the user sees is under system control compensation for this delay could be made by correctly timing the other paths in the system. Or, alternatively, if other paths are slower then the video of the real scene could be delayed. With an optical see-through display the view of the real world is instantaneous so it is not possible to compensate for system delays in other areas. On the other hand, with monitor based and video see-through displays a video camera is viewing the real scene. An advantage of this is that the image generated by the camera is available to the system to provide tracking information.
The optical see-through display does not have this additional information. The only position information available with that display is what can be provided by position sensors on the head mounted display itself.
4.2 TRACKING AND ORIENTATION SYSTEMS
The biggest challenge facing developers of augmented reality is the need to know where the user is located in reference to his or her surroundings.
In order to combine real and virtual worlds seamlessly so that the virtual objects align well with the real ones, an AR system needs to know two things precisely:
1) where the user is located, and
2) where he is looking.
A tracking system has to recognize these movements and project the graphics related to the real-world environment the user is seeing at any given moment. Currently, both video see-through and optical see-through displays typically have lag in the overlaid material due to the tracking technologies currently available. For augmented reality to reach its full potential, it must be usable both outdoors and indoors.
There are ways to increase tracking accuracy
Small area tracking and orientation systems
Tracking is easier in small spaces than in large spaces. Researchers at the University of North Carolina-Chapel Hill have developed a very precise system that works within 500 square feet. The HiBall Tracking System is an optoelectronic tracking system made of two parts:
¢ six user-mounted, optical sensors
¢ infrared-light-emitting diodes (LEDs) embedded in special ceiling panels
Photo courtesy Tracking Project at UNC-Chapel Hill
The Hiball Tracking System uses an optical sensing device and LED-embedded ceiling tiles to track movements over a short range.
The system uses the known location of the LEDs, the known geometry of the user-mounted optical sensors and a special algorithm to compute and report the user's position and orientation. The system resolves linear motion of less than .2 millimetres, and angular motions less than .03 degrees. It has an update rate of more than 1500 Hz, and latency is kept at about one millisecond
Large area tracking and orientation systems
For instance, the military uses multiple GPS (Global Positioning System) signals. There is also differential GPS, which involves using an area that has already been surveyed. Then the system would use a GPS receiver with an antenna that's location is known very precisely to track your location within that area. This will allow users to know exactly how inaccurate their GPS receivers are, and can adjust an augmented-reality system accordingly. Differential GPS allows for sub meter accuracy. A more accurate system being developed, known as real-time kinematic GPS, can achieve centimetre-level accuracy.
In case of out door application where the movement of user will be comparatively larger, his location with respect to his environments is tracked with the help of GPS RECEIVERS which works in coordination with the GPS satellites and the direction of vision of the user is calculated down to few degrees by INERTIAL/MAGNETIC TRACKER.
Tracking using GPS
The Global Positioning System (GPS) is actually a constellation of 27 Earth-orbiting satellites (24 in operation and three extras in case one fails). The U.S. military developed and implemented this satellite network as a military navigation system, but soon opened it up to everybody else.
Each of these 3,000- to 4,000-pound solar-powered satellites circles the globe at about 12,000 miles (19,300 km), making two complete rotations every day. The orbits are arranged so that at any time, anywhere on Earth, there are at least four satellites "visible" in the sky.
A GPS receiver's job is to locate four or more of these satellites, figure out the distance to each, and use this information to deduce its own location. This operation is based on a simple mathematical principle called trilateration
Positioning by 3-D trilateration
If we know we are 10 miles from satellite A in the sky, we could be anywhere on the surface of a huge, imaginary sphere with a 10-mile radius. If we also know we are 15 miles from satellite B, we can overlap the first sphere with another, larger sphere. The spheres intersect in a perfect circle. If we know the distance to a third satellite, we get a third sphere, which intersects with this circle at two points.
The Earth itself can act as a fourth sphere -- only one of the two possible points will actually be on the surface of the planet, so you can eliminate the one in space. Receivers generally look to four or more satellites, however, to improve accuracy and provide precise altitude information.
Measuring Distance
A GPS receiver calculates the distance to GPS satellites by timing a signal's journey from satellite to receiver. As it turns out, this is a fairly elaborate process. At a particular time (let's say midnight), the satellite begins transmitting a long, digital pattern called a pseudo-random code. The receiver begins running the same digital pattern also exactly at midnight. When the satellite's signal reaches the receiver, its transmission of the pattern will lag a bit behind the receiver's playing of the pattern. The length of the delay is equal to the signal's travel time. The receiver multiplies this time by the speed of light to determine how far the signal travelled. Assuming the signal travelled in a straight line, this is the distance from receiver to satellite. In order to make this measurement, the receiver and satellite both need clocks that can be synchronized down to the nanosecond. Every satellite contains an expensive atomic clock, but the receiver itself uses an ordinary quartz clock, which it constantly resets. In a nutshell, the receiver looks at incoming signals from four or more satellites and gauges its own inaccuracy.
When we measure the distance to four located satellites, we can draw four spheres that all intersect at one point. Three spheres will intersect even if our numbers are way off, but four spheres will not intersect at one point if we have measured incorrectly. Since the receiver makes all its distance measurements using its own built-in clock, the distances will all be proportionally incorrect. The receiver can easily calculate the necessary adjustment that will cause the four spheres to intersect at one point. Based on this, it resets its clock to be in sync with the satellite's atomic clock. The receiver does this constantly whenever it's on, which means it is nearly as accurate as the expensive atomic clocks in the satellites. In order for the distance information to be of any use, the receiver also has to know where the satellites actually are. This isn't particularly difficult because the satellites travel in very high and predictable orbits. The GPS receiver simply stores an almanac that tells it where every satellite should be at any given time. Things like the pull of the moon and the sun do change the satellites' orbits very slightly, but the Department of Defence constantly monitors their exact positions and transmits any adjustments to all GPS receivers as part of the satellites' signals
This system works pretty well, but inaccuracies do pop up. For one thing, this method assumes the radio signals will make their way through the atmosphere at a consistent speed (the speed of light). In fact, the Earth's atmosphere slows the electromagnetic energy down somewhat, particularly as it goes through the ionosphere and troposphere. The delay varies depending on where you are on Earth, which means it's difficult to accurately factor this into the distance calculations. Problems can also occur when radio signals bounce off large objects, such as skyscrapers, giving a receiver the impression that a satellite is farther away than it actually is. On top of all that, satellites sometimes just send out bad almanac data, misreporting their own position.
Differential GPS (DGPS) helps correct these errors. The basic idea is to gauge GPS inaccuracy at a stationary receiver station with a known location. Since the DGPS hardware at the station already knows its own position, it can easily calculate its receiver's inaccuracy. The station then broadcasts a radio signal to all DGPS-equipped receivers in the area, providing signal correction information for that area. In general, access to this correction information makes DGPS receivers much more accurate than ordinary receivers.
Thus the most essential function of a GPS receiver is to pick up the transmissions of at least four satellites and combine the information in those transmissions with information in an electronic almanac, all in order to figure out the receiver's position on Earth. Once the receiver makes this calculation, it can tell us the latitude, longitude and altitude (or some similar measurement) of its current position. To make the navigation more user-friendly, most receivers plug this raw data into map files stored in memory. We can use maps stored in the receiver's memory, connect the receiver to a computer that can hold more detailed maps in its memory. A standard GPS receiver will not only place us on a map at any particular location, but will also trace our path across a map as you move. If we leave our receiver on, it can stay in constant communication with GPS satellites to see how our location is changing.
ORIENTATION
For orientation, an inertial/magnetic tracker rides on a headband above the AR glasses. This device is a combination of miniature gyroscopes and accelerometers that detect head movements along with an electronic compass that establishes the direction of the viewer's gaze in relation to Earth's magnetic field.
4.3 MOBILE COMPUTING POWER
Mobile computing can be accomplished with the help of a wearable computer. A wearable computer is a battery-powered computer system worn on the user's body (on a belt, backpack or vest). It is designed for mobile and predominantly hands-free operations, often incorporating head-mounted displays and speech input.
The wearable computer is more than just a wristwatch or regular eyeglasses: it has the full functionality of a computer system but in addition to being a fully featured computer, it is also inextricably intertwined with the wearer. This is what sets the wearable computer apart from other wearable devices such as wristwatches, regular eyeglasses, wearable radios, etc
Three important features of wearable computers are
1.Constancy
The computer runs continuously, and is always ready'' to interact with the user. Unlike a hand-held device, laptop computer, or PDA, it does not need to be opened up and turned on prior to use. The signal flow from human to computer, and computer to human runs continuously to provide a constant user--interface.
2. Augmentation
Traditional computing paradigms are based on the notion that computing is the primary task. Wearable computing, however, is based on the notion that computing is NOT the primary task. The assumption of wearable computing is that the user will be doing something else at the same time as doing the computing. Thus the computer should serve to augment the intellect, or augment the senses. The signal flow between human and computer is depicted in the figure below
3.Mediation:
Unlike hand held devices, laptop computers, and PDAs, the wearable computer can encapsulate us. It doesn't necessarily need to completely enclose us, but the concept allows for a greater degree of encapsulation than traditional portable computers
5. APPLICATIONS
APPLICATIONS OF AR SYSTEMS.
1. Maintenance and construction
This is one of the first uses for augmented reality. Markers can be attached to a particular object that a person is working on, and the augmented-reality system can draw graphics on top of it. This is a more simple form of augmented reality, since the system only has to know where the user is in reference to the object that he or she is looking at. It's not necessary to track the person's exact physical location.
Eg: Usage if AR system in space frame construction
Space frames are typically made from a large number of components of similar size and shape (typically cylindrical struts and spherical nodes). Although the exterior dimensions of all the members may be identical, the forces they carry, and therefore their inner diameters, vary with their position in the structure. Consequently it is relatively easy to assemble pieces in the wrong position-which if undetected could lead to structural failure. Our augmented reality construction system is designed to guide workers through the assembly of a spaceframe structure, to ensure that each member is properly placed and fastened.
The spaceframe is assembled one component (strut or node) at a time. For each step of construction, the augmented reality system :
¢ Directs the worker to a pile of parts and tells her which part to pick up. This is currently done by displaying textual instructions and playing a sound file containing verbal instructions.
¢ Confirms that she has the correct piece. This is done by having her scan a barcode on the component.
¢ Directs her to install the component. A 3D virtual image of the component indicates where to install the component and verbal instructions played from a sound file explain how to install it.
¢ Verifies that the component is installed by asking her to scan the component with the tracked barcode scanner. This checks both the identity and position of the part.
Similarly, a repairperson viewing a broken piece of equipment could see instructions highlighting the parts that need to be inspected.
2. Military
The military has been devising uses for augmented reality for decades. The idea here is that an augmented-reality system could provide troops with vital information about their surroundings, such as showing where entrances are on the opposite end of a building, somewhat like X-ray vision. Augmented reality displays could also highlight troop movements, and give soldiers the ability to move to where the enemy can't see them.
In the AR future, a small team of soldiers airlifted into a remote combat area will encounter terrain that has been mapped in advance. Soldiers won't see just rocks, trees, and buildings, they'll see annotated warnings: "buried mines" or "enemy stores arms in this building." As surveillance reports flow into the command centre, new graphics will be broadcast to the AR gear.
3. Medical
Most of the medical applications deal with IMAGE GUIDED SURGERY. Pre-operative imaging studies, such as CT or MRI scans, of the patient provide the surgeon with the necessary view of the internal anatomy. From these images the surgery is planned. Visualization of the path through the anatomy to the affected area where, for example, a tumour must be removed is done by first creating a 3D model from the multiple views and slices in the preoperative study. This is most often done mentally though some systems will create 3D volume visualizations from the image study. Augmented reality can be applied so that the surgical team can see the CT or
MRI data correctly registered on the patient in the operating theatre while the procedure is progressing. Being able to accurately register the images at this point will enhance the performance of the surgical team and eliminate the need for the painful and cumbersome stereo tactic frames. Augmented reality systems can also be helpful in surgery to sense and MARK the vital parts so that the surgeon can be very careful at these regions.
Another application for augmented reality in the medical domain is in ULTRASOUND IMAGING. Using an optical see-through display the ultrasound technician can view a volumetric rendered image of the fetus overlaid on the abdomen of the pregnant woman. The image appears as if it was inside of the abdomen and is correctly rendered as the user moves.
Similarly, Patients admitted for routine breast biopsies and possible lumpectomies are randomly assigned to the AR test. Instead of the radiologist's usual practice of looking up at a sonogram screen and then back again at the patient, ultrasound images are seen through the physician's headgear as projected directly onto the patient's body. This provides a sort of virtual X-ray vision throughout the procedure. Breast lumps and other possibly cancerous anomalies show up as ghostly white outlines against an uneven grey background. And the position- and orientation-sensing technology in the head-mounted display lets the radiologist "see" where to
guide a biopsy needle with unprecedented precision. The hoped-for outcome of this AR application includes fewer complications and shorter recovery times for existing procedures, as well as the development of new surgical techniques. For brief procedures such as biopsies and laparoscopic (minimally invasive) surgery, a head-mounted AR display offers an ideal solution for combining actual and computer worlds.
4. Media and entertainment
A simple form of augmented reality has been in use in the entertainment and news business for quite some time. Whenever you are watching the evening weather report the weather reporter is shown standing in front of changing weather maps. In the studio the reporter is actually standing in front of a blue or green screen. This real image is augmented with computer generated maps using a technique called chroma-keying. It is also possible to create a virtual studio environment so that the actors can appear to be positioned in a studio with computer generated decorating. Augmented reality system allows broadcasters to insert advertisements into specific areas of the broadcast image . For example, while broadcasting a baseball game this system would be able to place an advertisement in the image so that it appears on the outfield wall of the stadium.
5. Gaming
The game could be projected onto the real world around you, and you could, literally, be in it as one of the characters. How cool would it be to take video games outside? The game could be projected onto the real world around you, and you could, literally, be in it as one of the characters. One Australian researcher has created a prototype game that combines Quake, a popular video game, with augmented reality. He put a model of a university campus into the game's software. Now, when he uses this system, the game surrounds him as he walks across campus.
6. IMPACT ON FUTURE LIFE
In Future-Everyday Life
There is no shortage of wish list applications for personal AR, whether handheld or head-mounted. Consider the home garage of the future, for instance. While fixing a car, there will no longer be the need to pull our head in and out from under the open hood to consult a bulky, greasy manual. With AR, we will simply slip on a tiny visor and guided repair instructions will appear next to each under-the-hood part that we gaze at: "Now that you've disconnected the radiator hose, move it to one side and unscrew the carburettor cap." Or we can retrieve the same data and navigate through parts information and replacement sales sites on the Web by merely holding a PDA-size position-sensing screen in front of any section of the engine.
And when AR headgear does shrink down to the size of common glasses, it could be a must for up-and-coming managers, to avoid career or social gaffes at business meetings and cocktail parties. Everyone will be packing extra data in their spectacles. Each time we look at someone across a conference table or a crowded room, information about who they are and what their background is could appear before your eyes. Learning how not to make it obvious that we are "scanning" a person's data will be a new business skill, like trying to look natural in front of a teleprompter.
7. CURRENT LIMITATIONS
Current Limitations
1. Accurate tracking and orientation is a problem in outdoors today because the tracking system currently used is sensitive to sudden variations in magnetic fields, the alignment of graphics and a street scene can be easily thrown off by even a stray remnant of 19th century technology like old iron trolley car tracks beneath asphalt. Moreover, a tracking system which can work accurately for a long time has not been developed yet.
2. The size of AR system is yet another problem. Augmented-reality displays are still pretty bulky; the weight and size of a wearable computer also needs to be brought down. Researchers believe that they will succeed in this within 2 years.
3. For a wearable augmented reality system, there is still not enough computing power to create stereo 3-D graphics. So researchers are using whatever they can get out of laptops and personal computers, for now. Laptops are just now starting to be equipped with graphics processing units (GPUs). Toshiba just added an NVidia GPU to their notebooks that is able to process more than 17-million triangles per second and 286-million pixels per second, which can enable CPU-intensive programs, such as 3-D games.
8. CONCLUSION
CONCLUSION
It's only a matter of time before augmented reality becomes part of our daily lives. With further developments, in future, the AR SYTEMS are going to become very compact, light weight and low cost units, so that it becomes very common in everyday life. Judging from the cell phones and palm-sized organizers that are already pervading our pockets, we can rightly predict that: "we'll feel left out if we don't have a personal augmented reality system to enhance our experience of the world."
9.BIBLIOGRAPHY
BIBLIOGRAPHY
1. Virtual architecture by zampi,guiiano
2. Optical and Optoelectronic instrumentation by Shanthi Prince,Anapurna
3. howstuffworks.com
4. imageguidedsurgery.com
5. gps.com
CONTENTS
ABSTRACT 1
1. INTRODUCTION 2
2. COMPARISON WITH VIRTUAL REALITY 5
3. EARLY DEVELOPMENT 8
4. COMPONENTS OF AUGMENTED REALITY SYSTEM 10
4.1 HEAD MOUNTED DISPLAYS 12
4.1.1 VIDEO SEE- THROUGH 13
4.1.2 OPTICAL SEE “ TROUGH 13
4.2 TRACKING AND ORIENTATION SYSTEMS 15
4.3 MOBILE COMPUTING POWER 20
5. APPLICATIONS 22
6. IMPACT ON FUTURE LIFE 28
7. CURRENT LIMITATIONS 30
8. CONCLUSION 32
9. BIBLIOGRAPHY 34
augmented reality
Augmented reality (AR) refers to computer displays that add virtual information to a user's sensory perceptions. Most AR research focuses on "see-through" devices, usually worn on the head that overlay graphics and text on the user's view of his or her surroundings. AR systems track the position and orientation of the user's head so that the overlaid material can be aligned with the user's view of the world.
Consider what AR could make routinely possible. A repairperson viewing a broken piece of equipment could see instructions highlighting the parts that need to be inspected. A surgeon could get the equivalent of x-ray vision by observing live ultrasound scans of internal organs that are overlaid on the patient's body. Soldiers could see the positions of enemy snipers who had been spotted by unmanned reconnaissance planes.
Getting the right information at the right time and the right place is key in all these applications. Personal digital assistants such as the Palm and the Pocket PC can provide timely information using wireless networking and Global Positioning System (GPS) receivers that constantly track the handheld devices. But what makes augmented reality different is how the information is presented: not on a separate display but integrated with the user's perceptions. In augmented reality, the user's view of the world and the computer interface literally become one.
1.INTRODUCTION
INTRODUCTION
Video games have been entertaining us for nearly 30 years. Computer graphics have become much more sophisticated since then, and soon, game graphics will seem all too real. In the next decade, researchers plan to pull graphics out of your television screen or computer display and integrate them into real-world environments. This new technology, called augmented reality, will further blur the line between what's real and what's computer-generated by enhancing what we see, hear, feel and smell. The basic idea of augmented reality is to superimpose graphics, audio and other sense enhancements over a real-world environment in real-time. 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.
Walk down the street, look at the world. This is reality. Now repeat, but wearing an odd-looking, bulky pair of glasses that place into your line of vision selective, relevant bits of data about the world or informative graphics and produce sound which will coincide with whatever you see.. This is augmented reality. An AR system, can superimpose computer generated text, graghics,3-D animation, sound, or any other digitised data on the real world. The augmented reality systems employ a see-through head-worn display that overlays graphics and sound on a person's naturally occurring sight and hearing. By tracking users and objects in space, these systems provide users with visual information that is tied to the physical environment. It 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.
Augmented-reality displays will overlay
computer-generated graphics onto the real world.
On the spectrum between virtual reality, which creates immersible, computer-generated environments, and the real world, augmented reality is closer to the real world. Augmented reality adds graphics, sounds, hap tics and smell to the natural world as it exists. You can expect video games to drive the development of augmented reality, but this technology will have countless applications. Everyone from tourists to military troops will benefit from the ability to place computer-generated graphics in their field of vision.
Augmented reality will truly change the way we view the world. 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. In this article, we will take a look at this future technology, its components and how it will be used.
2. COMPARISON WITH VIRTUAL REALITY
COMPARISON WITH VIRTUAL REALITY
Augmented reality is very much close to virtual reality. Virtual reality is a technology that encompasses a broad spectrum of ideas. The term was defined as "a computer generated, interactive, three-dimensional environment in which a person is immersed." Virtual reality creates immersible, computer generated environments which replaces real world .Here the head mounted displays block out all the external world from the viewer and present a view that is under the complete control of the computer.
A very visible difference between the 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. There must be a mechanism to combine the real and virtual that is not present in other virtual reality work. Developing the technology for merging the real and virtual image streams is an active research topic
Augmented reality is closer to the real world. Augmented reality adds graphics, sounds, hap tics and smell to the natural world, as it exists. Thus it augments the real world scene in such a way that the user can maintain a sense of presence in that world. That is, the user can interact with the real world , and at the same time can see, both the real and virtual world co-existing. For the same reason it has a large number of applications in the day to day life as compared to virtual reality.
The computer generated virtual objects must be accurately registered with the real world in all dimensions. Errors in this registration will prevent the user from seeing the real and virtual images as fused. The correct registration must also be maintained while the user moves about within the real environment. Discrepancies or changes in the apparent registration will range from distracting which makes working with the augmented view more difficult, to physically disturbing for the user making the system completely unusable. An immersive virtual reality system must maintain registration so that changes in the rendered scene match with the perceptions of the user. Any errors here are conflicts between the visual system and the kinesthetic or proprioceptive systems.
Milgram (Milgram and Kishino 1994; Milgram, Takemura et al. 1994) describes a taxonomy that identifies how augmented reality and virtual reality work are related. He defines the Reality-Virtuality continuum shown as Figure 2.
Figure 2 - 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 virtuality is a term created by Milgram to identify systems which are mostly synthetic with some real world imagery added such as texture mapping video onto virtual objects. This is a distinction that will fade as the technology improves and the virtual elements in the scene become less distinguishable from the real ones.
3. EARLY DEVELOPMENT
EARLY DEVELOPMENT
The first AR system was developed in the 1960s by computer graphics pioneer Ivan Sutherland and his students at Harvard University and the University of Utah. In the 1970s and 1980s a small number of researchers studied augmented reality at institutions such as the U.S. Air Force's Armstrong Laboratory, the NASA Ames Research Center and the University of North Carolina at Chapel Hill. It wasn't until the 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. Scientists have gathered at yearly AR conferences since 1998. 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."
4.COMPONENTS OF AUGMENTED
REALITY SYSTEM
COMPONENTS OF AUGMENTED REALITY SYSTEM
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. Here are the three components needed to make an augmented-reality system work :
¢ Head mounted displays
¢ Tracking and orientation system
¢ Mobile computing power
Photo courtesy Columbia University Computer Graphics and User Interfaces Lab
Early prototype of a mobile augmented-reality system
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. Let's take a look at each of the components of this system.
4.1 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. These forms one of the main components of an augmented reality system. They are used to merge the virtual world and real world in front of the user in such a way that he feels he is looking at a single real scene . They resemble some type of skiing goggles.
There are two basic types of HMDS:
¢ video see-through
¢ optical see-through
VIDEO SEE- THROUGH
Video see-through displays block out the wearer's surrounding environment, using small video cameras attached to the outside of the goggles to capture images. On the inside of the display, the video image is played in real-time and the graphics are superimposed on the video. One problem with the use of video cameras is that there is more lag, meaning that there is a delay in image-adjustment when the viewer moves his or her head.
OPTICAL SEE-THROUGH
Optical see-through displays is not fully realized yet. It is supposed to consist of a ordinary-looking pair of glasses that will have a light source on the side to project images on to the retina.
COMPARISON
There are advantages and disadvantages to each of these types of displays. With both of the displays that use a video camera to view the real world there is a forced delay of up to one frame time to perform the video merging operation. At standard frame rates that will be potentially a 33.33 millisecond delay in the view seen by the user. Since everything the user sees is under system control compensation for this delay could be made by correctly timing the other paths in the system. Or, alternatively, if other paths are slower then the video of the real scene could be delayed. With an optical see-through display the view of the real world is instantaneous so it is not possible to compensate for system delays in other areas. On the other hand, with monitor based and video see-through displays a video camera is viewing the real scene. An advantage of this is that the image generated by the camera is available to the system to provide tracking information.
The optical see-through display does not have this additional information. The only position information available with that display is what can be provided by position sensors on the head mounted display itself.
4.2 TRACKING AND ORIENTATION SYSTEMS
The biggest challenge facing developers of augmented reality is the need to know where the user is located in reference to his or her surroundings.
In order to combine real and virtual worlds seamlessly so that the virtual objects align well with the real ones, an AR system needs to know two things precisely:
1) where the user is located, and
2) where he is looking.
A tracking system has to recognize these movements and project the graphics related to the real-world environment the user is seeing at any given moment. Currently, both video see-through and optical see-through displays typically have lag in the overlaid material due to the tracking technologies currently available. For augmented reality to reach its full potential, it must be usable both outdoors and indoors.
There are ways to increase tracking accuracy
Small area tracking and orientation systems
Tracking is easier in small spaces than in large spaces. Researchers at the University of North Carolina-Chapel Hill have developed a very precise system that works within 500 square feet. The HiBall Tracking System is an optoelectronic tracking system made of two parts:
¢ six user-mounted, optical sensors
¢ infrared-light-emitting diodes (LEDs) embedded in special ceiling panels
Photo courtesy Tracking Project at UNC-Chapel Hill
The Hiball Tracking System uses an optical sensing device and LED-embedded ceiling tiles to track movements over a short range.
The system uses the known location of the LEDs, the known geometry of the user-mounted optical sensors and a special algorithm to compute and report the user's position and orientation. The system resolves linear motion of less than .2 millimetres, and angular motions less than .03 degrees. It has an update rate of more than 1500 Hz, and latency is kept at about one millisecond
Large area tracking and orientation systems
For instance, the military uses multiple GPS (Global Positioning System) signals. There is also differential GPS, which involves using an area that has already been surveyed. Then the system would use a GPS receiver with an antenna that's location is known very precisely to track your location within that area. This will allow users to know exactly how inaccurate their GPS receivers are, and can adjust an augmented-reality system accordingly. Differential GPS allows for sub meter accuracy. A more accurate system being developed, known as real-time kinematic GPS, can achieve centimetre-level accuracy.
In case of out door application where the movement of user will be comparatively larger, his location with respect to his environments is tracked with the help of GPS RECEIVERS which works in coordination with the GPS satellites and the direction of vision of the user is calculated down to few degrees by INERTIAL/MAGNETIC TRACKER.
Tracking using GPS
The Global Positioning System (GPS) is actually a constellation of 27 Earth-orbiting satellites (24 in operation and three extras in case one fails). The U.S. military developed and implemented this satellite network as a military navigation system, but soon opened it up to everybody else.
Each of these 3,000- to 4,000-pound solar-powered satellites circles the globe at about 12,000 miles (19,300 km), making two complete rotations every day. The orbits are arranged so that at any time, anywhere on Earth, there are at least four satellites "visible" in the sky.
A GPS receiver's job is to locate four or more of these satellites, figure out the distance to each, and use this information to deduce its own location. This operation is based on a simple mathematical principle called trilateration
Positioning by 3-D trilateration
If we know we are 10 miles from satellite A in the sky, we could be anywhere on the surface of a huge, imaginary sphere with a 10-mile radius. If we also know we are 15 miles from satellite B, we can overlap the first sphere with another, larger sphere. The spheres intersect in a perfect circle. If we know the distance to a third satellite, we get a third sphere, which intersects with this circle at two points.
The Earth itself can act as a fourth sphere -- only one of the two possible points will actually be on the surface of the planet, so you can eliminate the one in space. Receivers generally look to four or more satellites, however, to improve accuracy and provide precise altitude information.
Measuring Distance
A GPS receiver calculates the distance to GPS satellites by timing a signal's journey from satellite to receiver. As it turns out, this is a fairly elaborate process. At a particular time (let's say midnight), the satellite begins transmitting a long, digital pattern called a pseudo-random code. The receiver begins running the same digital pattern also exactly at midnight. When the satellite's signal reaches the receiver, its transmission of the pattern will lag a bit behind the receiver's playing of the pattern. The length of the delay is equal to the signal's travel time. The receiver multiplies this time by the speed of light to determine how far the signal travelled. Assuming the signal travelled in a straight line, this is the distance from receiver to satellite. In order to make this measurement, the receiver and satellite both need clocks that can be synchronized down to the nanosecond. Every satellite contains an expensive atomic clock, but the receiver itself uses an ordinary quartz clock, which it constantly resets. In a nutshell, the receiver looks at incoming signals from four or more satellites and gauges its own inaccuracy.
When we measure the distance to four located satellites, we can draw four spheres that all intersect at one point. Three spheres will intersect even if our numbers are way off, but four spheres will not intersect at one point if we have measured incorrectly. Since the receiver makes all its distance measurements using its own built-in clock, the distances will all be proportionally incorrect. The receiver can easily calculate the necessary adjustment that will cause the four spheres to intersect at one point. Based on this, it resets its clock to be in sync with the satellite's atomic clock. The receiver does this constantly whenever it's on, which means it is nearly as accurate as the expensive atomic clocks in the satellites. In order for the distance information to be of any use, the receiver also has to know where the satellites actually are. This isn't particularly difficult because the satellites travel in very high and predictable orbits. The GPS receiver simply stores an almanac that tells it where every satellite should be at any given time. Things like the pull of the moon and the sun do change the satellites' orbits very slightly, but the Department of Defence constantly monitors their exact positions and transmits any adjustments to all GPS receivers as part of the satellites' signals
This system works pretty well, but inaccuracies do pop up. For one thing, this method assumes the radio signals will make their way through the atmosphere at a consistent speed (the speed of light). In fact, the Earth's atmosphere slows the electromagnetic energy down somewhat, particularly as it goes through the ionosphere and troposphere. The delay varies depending on where you are on Earth, which means it's difficult to accurately factor this into the distance calculations. Problems can also occur when radio signals bounce off large objects, such as skyscrapers, giving a receiver the impression that a satellite is farther away than it actually is. On top of all that, satellites sometimes just send out bad almanac data, misreporting their own position.
Differential GPS (DGPS) helps correct these errors. The basic idea is to gauge GPS inaccuracy at a stationary receiver station with a known location. Since the DGPS hardware at the station already knows its own position, it can easily calculate its receiver's inaccuracy. The station then broadcasts a radio signal to all DGPS-equipped receivers in the area, providing signal correction information for that area. In general, access to this correction information makes DGPS receivers much more accurate than ordinary receivers.
Thus the most essential function of a GPS receiver is to pick up the transmissions of at least four satellites and combine the information in those transmissions with information in an electronic almanac, all in order to figure out the receiver's position on Earth. Once the receiver makes this calculation, it can tell us the latitude, longitude and altitude (or some similar measurement) of its current position. To make the navigation more user-friendly, most receivers plug this raw data into map files stored in memory. We can use maps stored in the receiver's memory, connect the receiver to a computer that can hold more detailed maps in its memory. A standard GPS receiver will not only place us on a map at any particular location, but will also trace our path across a map as you move. If we leave our receiver on, it can stay in constant communication with GPS satellites to see how our location is changing.
ORIENTATION
For orientation, an inertial/magnetic tracker rides on a headband above the AR glasses. This device is a combination of miniature gyroscopes and accelerometers that detect head movements along with an electronic compass that establishes the direction of the viewer's gaze in relation to Earth's magnetic field.
4.3 MOBILE COMPUTING POWER
Mobile computing can be accomplished with the help of a wearable computer. A wearable computer is a battery-powered computer system worn on the user's body (on a belt, backpack or vest). It is designed for mobile and predominantly hands-free operations, often incorporating head-mounted displays and speech input.
The wearable computer is more than just a wristwatch or regular eyeglasses: it has the full functionality of a computer system but in addition to being a fully featured computer, it is also inextricably intertwined with the wearer. This is what sets the wearable computer apart from other wearable devices such as wristwatches, regular eyeglasses, wearable radios, etc
Three important features of wearable computers are
1.Constancy
The computer runs continuously, and is always ready'' to interact with the user. Unlike a hand-held device, laptop computer, or PDA, it does not need to be opened up and turned on prior to use. The signal flow from human to computer, and computer to human runs continuously to provide a constant user--interface.
2. Augmentation
Traditional computing paradigms are based on the notion that computing is the primary task. Wearable computing, however, is based on the notion that computing is NOT the primary task. The assumption of wearable computing is that the user will be doing something else at the same time as doing the computing. Thus the computer should serve to augment the intellect, or augment the senses. The signal flow between human and computer is depicted in the figure below
3.Mediation:
Unlike hand held devices, laptop computers, and PDAs, the wearable computer can encapsulate us. It doesn't necessarily need to completely enclose us, but the concept allows for a greater degree of encapsulation than traditional portable computers
5. APPLICATIONS
APPLICATIONS OF AR SYSTEMS.
1. Maintenance and construction
This is one of the first uses for augmented reality. Markers can be attached to a particular object that a person is working on, and the augmented-reality system can draw graphics on top of it. This is a more simple form of augmented reality, since the system only has to know where the user is in reference to the object that he or she is looking at. It's not necessary to track the person's exact physical location.
Eg: Usage if AR system in space frame construction
Space frames are typically made from a large number of components of similar size and shape (typically cylindrical struts and spherical nodes). Although the exterior dimensions of all the members may be identical, the forces they carry, and therefore their inner diameters, vary with their position in the structure. Consequently it is relatively easy to assemble pieces in the wrong position-which if undetected could lead to structural failure. Our augmented reality construction system is designed to guide workers through the assembly of a spaceframe structure, to ensure that each member is properly placed and fastened.
The spaceframe is assembled one component (strut or node) at a time. For each step of construction, the augmented reality system :
¢ Directs the worker to a pile of parts and tells her which part to pick up. This is currently done by displaying textual instructions and playing a sound file containing verbal instructions.
¢ Confirms that she has the correct piece. This is done by having her scan a barcode on the component.
¢ Directs her to install the component. A 3D virtual image of the component indicates where to install the component and verbal instructions played from a sound file explain how to install it.
¢ Verifies that the component is installed by asking her to scan the component with the tracked barcode scanner. This checks both the identity and position of the part.
Similarly, a repairperson viewing a broken piece of equipment could see instructions highlighting the parts that need to be inspected.
2. Military
The military has been devising uses for augmented reality for decades. The idea here is that an augmented-reality system could provide troops with vital information about their surroundings, such as showing where entrances are on the opposite end of a building, somewhat like X-ray vision. Augmented reality displays could also highlight troop movements, and give soldiers the ability to move to where the enemy can't see them.
In the AR future, a small team of soldiers airlifted into a remote combat area will encounter terrain that has been mapped in advance. Soldiers won't see just rocks, trees, and buildings, they'll see annotated warnings: "buried mines" or "enemy stores arms in this building." As surveillance reports flow into the command centre, new graphics will be broadcast to the AR gear.
3. Medical
Most of the medical applications deal with IMAGE GUIDED SURGERY. Pre-operative imaging studies, such as CT or MRI scans, of the patient provide the surgeon with the necessary view of the internal anatomy. From these images the surgery is planned. Visualization of the path through the anatomy to the affected area where, for example, a tumour must be removed is done by first creating a 3D model from the multiple views and slices in the preoperative study. This is most often done mentally though some systems will create 3D volume visualizations from the image study. Augmented reality can be applied so that the surgical team can see the CT or
MRI data correctly registered on the patient in the operating theatre while the procedure is progressing. Being able to accurately register the images at this point will enhance the performance of the surgical team and eliminate the need for the painful and cumbersome stereo tactic frames. Augmented reality systems can also be helpful in surgery to sense and MARK the vital parts so that the surgeon can be very careful at these regions.
Another application for augmented reality in the medical domain is in ULTRASOUND IMAGING. Using an optical see-through display the ultrasound technician can view a volumetric rendered image of the fetus overlaid on the abdomen of the pregnant woman. The image appears as if it was inside of the abdomen and is correctly rendered as the user moves.
Similarly, Patients admitted for routine breast biopsies and possible lumpectomies are randomly assigned to the AR test. Instead of the radiologist's usual practice of looking up at a sonogram screen and then back again at the patient, ultrasound images are seen through the physician's headgear as projected directly onto the patient's body. This provides a sort of virtual X-ray vision throughout the procedure. Breast lumps and other possibly cancerous anomalies show up as ghostly white outlines against an uneven grey background. And the position- and orientation-sensing technology in the head-mounted display lets the radiologist "see" where to
guide a biopsy needle with unprecedented precision. The hoped-for outcome of this AR application includes fewer complications and shorter recovery times for existing procedures, as well as the development of new surgical techniques. For brief procedures such as biopsies and laparoscopic (minimally invasive) surgery, a head-mounted AR display offers an ideal solution for combining actual and computer worlds.
4. Media and entertainment
A simple form of augmented reality has been in use in the entertainment and news business for quite some time. Whenever you are watching the evening weather report the weather reporter is shown standing in front of changing weather maps. In the studio the reporter is actually standing in front of a blue or green screen. This real image is augmented with computer generated maps using a technique called chroma-keying. It is also possible to create a virtual studio environment so that the actors can appear to be positioned in a studio with computer generated decorating. Augmented reality system allows broadcasters to insert advertisements into specific areas of the broadcast image . For example, while broadcasting a baseball game this system would be able to place an advertisement in the image so that it appears on the outfield wall of the stadium.
5. Gaming
The game could be projected onto the real world around you, and you could, literally, be in it as one of the characters. How cool would it be to take video games outside? The game could be projected onto the real world around you, and you could, literally, be in it as one of the characters. One Australian researcher has created a prototype game that combines Quake, a popular video game, with augmented reality. He put a model of a university campus into the game's software. Now, when he uses this system, the game surrounds him as he walks across campus.
6. IMPACT ON FUTURE LIFE
In Future-Everyday Life
There is no shortage of wish list applications for personal AR, whether handheld or head-mounted. Consider the home garage of the future, for instance. While fixing a car, there will no longer be the need to pull our head in and out from under the open hood to consult a bulky, greasy manual. With AR, we will simply slip on a tiny visor and guided repair instructions will appear next to each under-the-hood part that we gaze at: "Now that you've disconnected the radiator hose, move it to one side and unscrew the carburettor cap." Or we can retrieve the same data and navigate through parts information and replacement sales sites on the Web by merely holding a PDA-size position-sensing screen in front of any section of the engine.
And when AR headgear does shrink down to the size of common glasses, it could be a must for up-and-coming managers, to avoid career or social gaffes at business meetings and cocktail parties. Everyone will be packing extra data in their spectacles. Each time we look at someone across a conference table or a crowded room, information about who they are and what their background is could appear before your eyes. Learning how not to make it obvious that we are "scanning" a person's data will be a new business skill, like trying to look natural in front of a teleprompter.
7. CURRENT LIMITATIONS
Current Limitations
1. Accurate tracking and orientation is a problem in outdoors today because the tracking system currently used is sensitive to sudden variations in magnetic fields, the alignment of graphics and a street scene can be easily thrown off by even a stray remnant of 19th century technology like old iron trolley car tracks beneath asphalt. Moreover, a tracking system which can work accurately for a long time has not been developed yet.
2. The size of AR system is yet another problem. Augmented-reality displays are still pretty bulky; the weight and size of a wearable computer also needs to be brought down. Researchers believe that they will succeed in this within 2 years.
3. For a wearable augmented reality system, there is still not enough computing power to create stereo 3-D graphics. So researchers are using whatever they can get out of laptops and personal computers, for now. Laptops are just now starting to be equipped with graphics processing units (GPUs). Toshiba just added an NVidia GPU to their notebooks that is able to process more than 17-million triangles per second and 286-million pixels per second, which can enable CPU-intensive programs, such as 3-D games.
8. CONCLUSION
CONCLUSION
It's only a matter of time before augmented reality becomes part of our daily lives. With further developments, in future, the AR SYTEMS are going to become very compact, light weight and low cost units, so that it becomes very common in everyday life. Judging from the cell phones and palm-sized organizers that are already pervading our pockets, we can rightly predict that: "we'll feel left out if we don't have a personal augmented reality system to enhance our experience of the world."
9.BIBLIOGRAPHY
BIBLIOGRAPHY
1. Virtual architecture by zampi,guiiano
2. Optical and Optoelectronic instrumentation by Shanthi Prince,Anapurna
3. howstuffworks.com
4. imageguidedsurgery.com
5. gps.com
CONTENTS
ABSTRACT 1
1. INTRODUCTION 2
2. COMPARISON WITH VIRTUAL REALITY 5
3. EARLY DEVELOPMENT 8
4. COMPONENTS OF AUGMENTED REALITY SYSTEM 10
4.1 HEAD MOUNTED DISPLAYS 12
4.1.1 VIDEO SEE- THROUGH 13
4.1.2 OPTICAL SEE “ TROUGH 13
4.2 TRACKING AND ORIENTATION SYSTEMS 15
4.3 MOBILE COMPUTING POWER 20
5. APPLICATIONS 22
6. IMPACT ON FUTURE LIFE 28
7. CURRENT LIMITATIONS 30
8. CONCLUSION 32
9. BIBLIOGRAPHY 34
augmented reality
