Augmented Reality

A Seminar Report
On
“Augmented Reality”
Submitted for partial fulfillment of
BACHELOR OF TECHNOLOGY
Degree
In
Electrical & Electronics Engineering
Submitted by :
Avinav Prince
EN-3rd
YR
Section ‘I’ Roll no. 18
University Roll no. 0906321027

CONTENTS
• Introduction
• Augmented Reality vs. Virtual Reality
• Components of Augmented Reality System
o Head Mounted Display
o Tracking System (GPS)
o Mobile Computing Power
• Video Merging
• THE RESEARCH
• GLOBAL POSITIONING SYSTEM
o HOW GPS WORKS
o Factors affecting GPS signals:
• APPLICATIONS DOMAINS OF AR SYSTEM
• Performance issues of augmented reality system
• Conclusion

Augmented Reality
Introduction
Augmented Reality (AR) is a growing area in virtual reality research. The world
environment around us provides a wealth of information that is difficult to
duplicate in a computer. This is evidenced by the worlds used in virtual
environments. Either these worlds are very simplistic such as the environments
created for immersive entertainment and games, or the system that can create a
more realistic environment has a million dollar price tag such as flight simulators.
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 presented to the user enhances that person's performance in and
perception of the world. The ultimate goal is to create a system such that the user
cannot 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.
Augmented Reality vs. Virtual Reality
Virtual reality is a technology that encompasses a broad spectrum of ideas. The
term is defined as "a computer generated, interactive, three-dimensional
environment in which a person is immersed. There are three key points in this
definition. First, this virtual environment is a computer generated three-
dimensional scene, which requires high performance computer graphics to provide
an adequate level of realism. The second point is that 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. The last point is that 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 wearer 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.

The discussion above highlights the similarities and differences between virtual
reality and augmented reality systems. A very visible difference between these
two types of systems is the immersiveness of the system. Virtual reality strives for
a totally immersive environment. 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. 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. Milgram 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 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.

Video Merging
The task in the augmented reality system is to register the virtual frame of
reference with what the user is seeing. Registration is more critical in an
augmented reality system because we are more sensitive to visual misalignments
than to the type of vision-kinesthetic errors that might result in a standard virtual
reality system. Figure shows the multiple reference frames that must be related in
an augmented reality system.
The scene is viewed by an imaging device, which in this case is depicted as a video
camera. The camera performs a perspective projection of the 3D world onto a 2D
image plane. The generation of the virtual image is done with a standard computer
graphics system. The virtual objects are modeled in an object reference frame. The
graphics system requires information about the imaging of the real scene so that it
can correctly render these objects. This data will control the synthetic camera that
is used to generate the image of the virtual objects. This image is then merged
with the image of the real scene to form the augmented reality image.
Components of Augmented Reality System

1. Head Mounted Display
2. Tracking System (GPS)
3. Mobile Computing Power
Head Mounted Displays
They enable us to view graphics and text created by the augmented reality system.
There are two basic types of head mounted displays being used.
1. Video See-Through Display
The "see-through" designation comes from the need for the user to be able to see
the real worldview that is immediately in front of him even when wearing the
HMD. This system blocks the wearers surrounding environment using small
cameras attached to the outside of the goggle 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.
Video See-through Display

The head position obtained through the video camera by the process as
explained above is the input to the graphics system. Graphics System produces
the virtual objects, which are aligned to that of real objects, virtual objects are
then merged with the real objects generated by the video camera and sent to
the monitor from where it is displayed to the user.
2.Optical See-Through Displays
The optical see-through HMD eliminates the video channel that is looking at the
real scene. Instead merging of real world and virtual augmentation is done
optically in front of the user.
Optical See-Through Display
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 position sensors on the head can provide
mounted display itself. The major advantage of optical see through display is
that they could be made very small however the biggest constraint in using this
technology is the prohibitive cost.
The main components of our system are a backpack computer (with
3D graphics acceleration), a differential GPS system, a head-worn
display interface (with orientation tracker), and a spread
spectrum radio communication link, all attached to the backpack

The above shown figure is the block diagram of AR system. It consists of a backup
PC to which two inputs one from the GPS receiver and other from the head
mounted display comes. The signal from the GPS receiver tells the co-ordinates of
the person and the orientation tracker gives the orientation of the head. These
two inputs will be transferred through the satellite to the database server. This
server based according to the information received sends the related database to
the satellite, which is then transmitted to the backpack PC. The graphics card will
generate the virtual objects, which are then merged with the real environment by
the head worn display interface and displayed to the user.
The Research
The discipline of affective computing studies how computers can recognize,
understand, and mimic human emotions. Now, in most cyberpunk stories where
humans merge their minds with computers, the computer is able to interpret the
symbolic thinking of its human companion, and insert symbolic ideas back into the
human brain. But wouldn't it be better if the computer could interpret
our values instead?
In fact, it would probably be far easier for computers to learn to recognize what
we like, dislike, approve of or are uncomfortable with--these base responses tend
to be similar between people, and even across cultural and linguistic barriers.
While each of us probably has a unique encoding for the concept "carrot" in our
brains, we almost certainly share a basic neural and physiological response when
asked whether we like carrots. I.e. you can teach a computer to recognize that
someone is enjoying the carrot they're munching--but probably you can't teach
the computer to recognize when someone is thinking about carrots.
Basically it's just that the internet is so full of information, we end up spending
most of our time filtering out the irrelevant data. If you think about it, like/dislike
is the basic crap filter--a computer that could tell you hated pop-up browser ads
without being asked would be a good thing.

Looking not too far in the future, we see a world where everybody is immersed in
one form or another of augmented reality. Everywhere we look, we see
annotations on reality, provided by our AR glasses. The issue then becomes the
same as the one we face with the Internet today: how to filter out all the crap?
This is where the values-driven interface becomes crucial. Our AR system needs to
be able to recognize our reactions to the various cues, annotations, pop-ups,
overlays, sims, and pointers. If our system can do this, it can edit out the things we
don't want to see.
e.g. Orthodox religious types no longer see ads for girlie shows or salacious lingerie
models on billboards; serious rationalists no longer see the corner church as they
walk by. Something else replaces it, a soothing image of the Gandhiji or
something... The point is, the augmented world reflects the values of whoever is
using it, and it does so seamlessly and automatically.

We introduce a hand held PC in the basic AR diagram. This handheld PC
has been specifically trained by the users to understand his likes and
dislikes. Now the Back Pack pc will receive input not only from GPS and
orientation tracker but also from the hand held PC. Now according to
this information it would be decided which data has to be accessed. e.g.
if the person is in front of a real object which he hated to see, this
information will be conveyed by the handheld pc to the back pack pc

which in turn will generate virtual objects so to superimpose the real
object the user hates. Thus filtering all the irrelevant information for the
user and helping him.
GLOBAL POSITIONING SYSTEM
Where am I? The question seems simple; the answer, historically, has proved not
to be. For centuries, navigators and explorers have searched the heavens
for a system that would enable them to locate their position on the globe
with the accuracy necessary to avoid tragedy and to reach their intended
destinations. On June 26, 1993, however, the answer became as simple as
the question. On that date, the U.S. Air Force launched the 24th Navstar
satellite into orbit, completing a network of 24 satellites known as
the Global Positioning System, or GPS. With a GPS receiver that costs less
than a few hundred dollars you can instantly learn your location on the
planet--your latitude, longitude, and even altitude--to within a few hundred
feet.
This incredible new technology was made possible by a combination of
scientific and engineering advances, particularly development of the world's
most accurate timepieces: atomic clocksthat are precise to within a billionth
of a second. The clocks were created by physicists seeking answers to
questions about the nature of the universe, with no conception that their
technology would some day lead to a global system of navigation. Today,
GPS is saving lives, helping society in countless other ways, and generating
100,000 jobs in a multi-billion-dollar industry. It provides a
dramatic example of how science works and how basic
GPS SYSTEM SEGMENTS

The GPS consists of three major segments: SPACE, CONTROL and USER.
1.SPACE SEGMENT
The SPACE segment consists of 24 operational satellites in six orbital planes (four
satellites in each plane). The satellites operate in circular 20,200 km orbits at an
inclination angle of 55 degrees and with a 12-hour period. The position is
therefore the same at the same sidereal time each day, i.e. the satellites appear 4
minutes earlier each day.
2.CONTROL SEGMENT
The CONTROL segment consists of five Monitor Stations (Hawaii, Kwajalein,
Ascension Island, Diego Garcia, Colorado Springs), three Ground Antennas,
(Ascension Island, Diego Garcia, Kwajalein), and a Master Control Station
(MCS) located at Schriever AFB in Colorado. The monitor stations passively track
all satellites in view, accumulating ranging data. This information is processed at
the MCS to determine satellite orbits and to update each satellite's navigation
message. Updated information is transmitted to each satellite via the Ground
Antennas.
3.USER SEGMENT
The USER segment consists of antennas and receiver-processors that provide
positionin research leads to technologies that were virtually unimaginable at the
time the research was done.

HOW GPS WORKS
1. The basis of GPS is "triangulation" from satellites.
2. To "triangulate," a GPS receiver measures distance using the travel time of
radio signals.
3. To measure travel time, GPS needs very accurate timing, which it achieves
with some tricks.
4. Along with distance, we need to know exactly where the satellites are in
space. High orbits and careful monitoring are the secret.
5. Finally you must correct for any delays the signal experiences as it travels
through the atmosphere.
Triangulation from Satellites:
Suppose we measure our distance from a satellite and find it to be 11,000 miles.
Knowing that we're 11,000 miles from a particular satellite narrows down all the
possible locations we could be in the whole universe to the surface of a sphere
that is centered on this satellite and has a radius of 11,000 miles. Next, say we
measure our distance to a second satellite and find out that it's 12,000 miles away.
That tells us that we're not only on the first sphere but we're also on a sphere
that's 12,000 miles from the second satellite. Or in other words, we're somewhere
on the circle where these two spheres intersect. If we then make a measurement
from a third satellite and find that we're 13,000 miles from that one, that narrows
our position down even further, to the two points where the 13,000 mile sphere
cuts through the circle that's the intersection of the first two spheres. So by
ranging from three satellites we can narrow our position to just two points in
space.
To decide which one is our true location we could make a fourth measurement.
But usually one of the two points is a ridiculous answer (either too far from Earth
or moving at an impossible velocity) and can be rejected without a measurement.

Measuring distance from satellite:
The basic problem is in finding the distance of the user from the four satellites.
This can be done if we know the time taken by the signal from the satellite to
reach to the receiver. Then the total distance is given by
DISTANCE (between the satellite and the user) = TIME (taken by the signal to reach earth)*
SPEED (of the signal which is the speed of light).
The time taken by the signal to reach from satellite to the receiver can be found by
calculating the phase shift of the Pseudo Random Code
Pseudo Random Code:
The Pseudo Random Code is a fundamental part of GPS. Physically it's just a very
complicated digital code, or in other words, a complicated sequence of "on" and
"off" pulses. The signal is so complicated that it almost looks like random electrical
noise. Hence the name "Pseudo-Random." There are several good reasons for that
complexity: First, the complex pattern helps make sure that the receiver doesn't
accidentally sync up to some other signal. The patterns are so complex that it's
highly unlikely that a stray signal will have exactly the same shape. Since each
satellite has its own unique Pseudo-Random Code this complexity also guarantees
that the receiver won't accidentally pick up another satellite's signal. So all the
satellites can use the same frequency without jamming each other. And it makes it
more difficult for a hostile force to jam the system. We assume that both the
satellite and the receiver start generating their codes at exactly the same time.
Distance to a satellite is determined by measuring how long a radio signal takes to
reach us from that satellite.
To make the measurement we assume that both the satellite and our receiver are

generating the same pseudo-random codes at exactly the same time.
1. By comparing how late the satellite's pseudo-random code appears compared
to our receiver's code, we determine how long it took to reach us.
2. Multiply that travel time by the speed of light and you've got distance.
But how do we make sure everybody is perfectly synchronized?
If measuring the travel time of a radio signal is the key to GPS, then our stop
watches had better be darn good, because if their timing is off by just a
thousandth of a second, at the speed of light, that translates into almost 200 miles
of error!
On the satellite side, timing is almost perfect because they have incredibly
precise atomic clocks on board.
Atomic clocks don't run on atomic energy. They get the name because they use
the oscillations of a particular atom as their "metronome." This form of timing is
the most stable and accurate reference man has ever developed.
Remember that both the satellite and the receiver need to be able to precisely
synchronize their pseudo-random codes to make the system work. Our receivers
needed atomic clocks (which costs a lot) nobody could afford it. The secret to
perfect timing is to make an extra satellite measurement. If our receiver's clocks
were perfect, then all our satellite ranges would intersect at a single point (which
is our position). But with imperfect clocks, a fourth measurement, done as a
crosscheck, will NOT intersect with the first three. Since any offset from universal
time will affect all of our measurements, the receiver looks for a single correction
factor that it can subtract from all its timing measurements that would cause them
all to intersect at a single point. That correction brings the receiver's clock back
into sync with universal time . Once it has that correction it applies to all the rest
of its measurements and now we've got precise position of accuracy upto 3-6 mts.
Precise Positioning Service (PPS)
• Authorized users with cryptographic equipment and keys and specially
equipped receivers use the Precise Positioning System. U. S. and Allied

military, certain U.S Government agencies, and selected civil users
specifically approved by the U.S. Government, can use the PPS.
• PPS Predictable Accuracy
o 22 meter Horizontal accuracy
o 27.7 meter vertical accuracy
Standard Positioning Service (SPS)
• Civil users worldwide use the SPS without charge or restrictions. Most
receivers are capable of receiving and using the SPS signal. The SPS accuracy
is intentionally degraded by the DOD by the use of Selective Availability.
• SPS Predictable Accuracy
o 100 meter horizontal accuracy
o 156 meter vertical accuracy
GPS Satellite Signals
• The SVs transmit two microwave carrier signals. The L1 frequency (1575.42
MHz) carries the navigation message and the SPS code signals. The L2
frequency (1227.60 MHz) is used to measure the ionospheric delay by PPS
equipped receivers.
• Three binary codes shift the L1 and/or L2 carrier phase.
o The C/A Code (Coarse Acquisition) modulates the L1 carrier phase.
The C/A code is a repeating 1 MHz Pseudo Random Noise (PRN) Code.
This noise-like code modulates the L1 carrier signal, "spreading" the
spectrum over a 1 MHz bandwidth. The C/A code repeats every 1023
bits (one millisecond). There is a different C/A code PRN for each SV.
GPS satellites are often identified by their PRN number, the unique
identifier for each pseudo-random-noise code. The C/A code that
modulates the L1 carrier is the basis for the civil SPS.
o The P-Code (Precise) modulates both the L1 and L2 carrier phases.
The P-Code is a very long (seven days) 10 MHz PRN. The P-Code is
encrypted into the Y-Code. The encrypted Y-Code requires a classified
AS Module for each receiver channel and is for use only by authorized
users with cryptographic keys. The P (Y)-Code is the basis for the PPS.
o The Navigation Message also modulates the L1-C/A code signal. The
Navigation Message is a 50 Hz signal consisting of data bits that
describe the GPS satellite orbits, clock corrections, and other system
parameters.

GPS Data
• The GPS Navigation Message consists of time-tagged data bits marking the
time of transmission of each sub frame at the time they are transmitted by
the SV. A data bit frame consists of 1500 bits divided into five 300-bit sub
frames. A data frame is transmitted every thirty seconds. Three six-second
sub frames contain orbital and clock data. SV Clock corrections are sent in
sub frame one and precise SV orbital data sets (ephemeris data parameters)
for the transmitting SV are sent in sub frames two and three. Sub frames
four and five are used to transmit different pages of system data. An entire
set of twenty-five frames (125 sub frames) makes up the complete
Navigation Message that is sent over a 12.5 minute period.
• Data frames (1500 bits) are sent every thirty seconds. Each frame consists of
five sub frames.
• Data bit sub frames (300 bits transmitted over six seconds) contain parity
bits that allow for data checking and limited error correction
Factors affecting GPS signals:
1.Ionosphere and Troposphere delays: The signal from the satellite slows down
while passing through the ionosphere and troposphere before reaching the
receiver. GPS system uses an inbuilt model that calculates the average amount of
delay.
2. Signal and Multipath: While coming from the satellite signal may get reflected of
by high buildings or some other objects before it reaches the receiver. Thus
causing an extra timing error.
3. Orbital Errors: These errors are also known as ephemeris error. These are the
inaccuracy of satellites while orbiting the earth.
4. Receiver Clock errors: As we use an ordinary quartz clock in the GPS receiver it
introduces certain timing errors.
Geometric Dilution of Precision (GDOP):
There are usually more satellites available than a receiver need to fix a position so
the receiver picks a few and ignores the rest. These picks should be as far from

each other in the space as possible as for maximum accuracy the spheres should
intersect at almost right angles.
The accuracy achieved by this GPS system is 3-6 mts. but for Augmented Reality
accuracy in centimeters is required. For that purpose we use Differential GPS
Systems.
Differential GPS Systems:
It is a way to correct various inaccuracies. It involves the co-operation of two
receivers out of which one is stationary and the other one is with the user. The
stationary receiver ties all the satellite measurements into a solid local reference.
The reference receiver is put onto a point that has been very accurately surveyed.
It receives the GPS signal and works in reverse order that is instead of using timing
signal to calculate the position, It uses the known position to calculate the time
and then compare it with the actual time that the signal must have taken from the
satellite to reach the receiver. This error information is then transferred to the
roving receiver. At a particular moment the stationary receiver doesn’t know
which satellites are being used by the roving receiver. So it calculates the timing
error from all the 24 satellites and sends this information to the roving one. The
roving receiver then uses the required information to calculate the correction
factor and neglect the rest of information.
Mobile Computing Power
This is the component of the AR system, which generates all the virtual objects and
merges the real based environment with the virtual objects. It is a communicator
between the AR system and the database server.
APPLICATIONS DOMAINS OF AR SYSTEM
1. 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.
2. Military Training
The military has been using displays in cockpits that present information to the
pilot on the windshield of the cockpit or the visor of their flight helmet. This is a
form of augmented reality display. SIMNET, a distributed war games simulation
system, is also embracing augmented reality technology. By equipping military
personnel with helmet mounted visor displays or a special purpose rangefinder the
activities of other units participating in the exercise can be imaged. While looking
at the horizon, for example, the display-equipped soldier could see a helicopter
rising above the tree line. This helicopter could be being flown in simulation by
another participant. In wartime, the display of the real battlefield scene could be
augmented with annotation information or highlighting to emphasize hidden
enemy units.
3. Engineering Design
Imagine that a group of designers are working on the model of a complex device
for their clients. The designers and clients want to do a joint design review even
though they are physically separated. If each of them had a conference room that
was equipped with an augmented reality display this could be accomplished. The
physical prototype that the designers have mocked up is imaged and displayed in
the client's conference room in 3D. The clients can walk around the display looking
at different aspects of it. To hold discussions the client can point at the prototype
to highlight sections and this will be reflected on the real model in the augmented
display that the designers are using. Or perhaps in an earlier stage of the design,
before a prototype is built, the view in each conference room is augmented with a
computer-generated image of the current design built from the CAD files
describing it. This would allow real time interaction with elements of the design so
that either side can make adjustments and changes that are reflected in the view
seen by both groups.
4.Manufacturing, Maintenance and Repair

When the maintenance technician approaches a new or unfamiliar piece of
equipment instead of opening several repair manuals they could put on an
augmented reality display. In this display the image of the equipment would be
augmented with annotations and information pertinent to the repair. For example,
the location of fasteners and attachment hardware that must be removed would
be highlighted. Then the inside view of the machine would highlight the boards
that need to be replaced worn by personnel that is attached to an optical see-
through display The wireless connection allows the soldier to access repair
manuals and images of the equipment. Future versions might register those
images on the live scene and provide animation to show the procedures that must
be performed.
5. Consumer Design
Virtual reality systems are already used for consumer design. Using perhaps more
of a graphics system than virtual reality, when you go to the typical home store
wanting to add a new deck to your house, they will show you a graphical picture of
what the deck will look like. It is conceivable that a future system would allow you
to bring a video tape of your house shot from various viewpoints in your backyard
and in real time it would augment that view to show the new deck in its finished
form attached to our house. Or bring in a tape of your current kitchen and the
augmented reality processor would replace your current kitchen cabinetry with
virtual images of the new kitchen that you are designing.
Applications in the fashion and beauty industry that would benefit from an
augmented reality system can also be imagined. If the dress store does not have a
particular style dress in your size an appropriate sized dress could be used to
augment the image of you. As you looked in the three-sided mirror you would see
the image of the new dress on your body. Changes in hem length, shoulder styles
or other particulars of the design could be viewed on you before you place the
order. When you head into some high-tech beauty shops today you can see what a
new hairstyle would look like on a digitized image of yourself. But with an
advanced augmented reality system you would be able to see the view as you
moved. If the dynamics of hair were included in the description of the virtual
object you would also see the motion of your hair as your head moved
6.Instant information

Tourists and students could use these systems to learn more about a certain
historical event. Imagine walking onto a Civil War battlefield and seeing a re-
creation of historical events on a head-mounted, augmented-reality display. It
would immerse you in the event, and the view would be panoramic.
7.Gaming
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. When one uses this system, the game surrounds him as he walks
across campus.
There are hundreds of potential applications for such a technology, gaming and
entertainment being the most obvious ones. Any system that gives people instant
information, requiring no research on their part, is bound to be a valuable to
anyone in pretty much any field. Augmented-reality systems will instantly
recognize what someone is looking at, and retrieve and display the data related to
that view.
Performance issues of augmented reality system
Augmented reality systems are expected to run in real-time so that a user will be
able to move about freely within the scene and see a properly rendered
augmented image. This places two performance criteria on the system. They are:
• Update rate for generating the augmenting image,
• Accuracy of the registration of the real and virtual image.
Visually the real-time constraint is manifested in the user viewing an augmented
image in which the virtual parts are rendered without any visible jumps. To appear
without any jumps, a standard rule of thumb is that the graphics system must be
able to render the virtual scene at least 10 times per second. This is well within the
capabilities of current graphics systems for simple to moderate graphics scenes.
For the virtual objects to realistically appear part of the scene more photorealistic

graphics rendering is required. The current graphics technology does not support
fully lit, shaded and ray-traced images of complex scenes. Fortunately, there are
many applications for augmented reality in which the virtual part is either not very
complex or will not require a high level of photorealism.
Failures in the second performance criterion have two possible causes. One is a
misregistration of the real and virtual scene because of noise in the system. The
position and pose of the camera with respect to the real scene must be sensed.
Any noise in this measurement has the potential to be exhibited as errors in the
registration of the virtual image with the image of the real scene. Fluctuations of
values while the system is running will cause jittering in the viewed image. As
mentioned previously, our visual system is very sensitive to visual errors, which in
this case would be the perception that the virtual object is not stationary in the
real scene or is incorrectly positioned. Misregistrations of even a pixel can be
detected under the right conditions. The second cause of misregistration is time
delays in the system. As mentioned in the previous paragraph, a minimum cycle
time of 0.1 seconds is needed for acceptable real-time performance. If there are
delays in calculating the camera position or the correct alignment of the graphics
camera then the augmented objects will tend to lag behind motions in the real
scene. The system design should minimize the delays to keep overall system delay
within the requirements for real-time performance.
CONCLUSION
Though Augmented Reality is in a nascent stage and is still not being used in mass.
We feel that with the growing research in AR and shrinking size and complexity of
AR system it is not far away in time where everybody will own his own AR system.

Augmented realities as an emerging technology offer new opportunities due to
several shifting external conditions or changing forms of social interaction. In order
to investigate possible impacts, trends and relationships the employed method is
based on an environmental scanning and on several semi-structured interviews,
conducted with several technology experts, researchers and futurologists. The
process aims to obtain valuable information on competitors, markets, customers
and suppliers as well as on macroeconomic factors, such as social, economic,
technological and political factors. The main research findings afforded that AR can
be seen as a new communication medium or tool in an early stage level due to
several major technical and social challenges and that it goes along with the
evolving information technology. These days one of the most promising devices
for AR applications is the mobile phone, which could open the floodgates for the
mass implementation of AR. With regard to the evolving ubiquity of information
and interactivity through smart things and sensors, AR will provide customized-,
perceptional-, and location-based information. Life and task enhancing services
and applications are assigned big potential in future solutions, which could occur
in many areas and industries. Due to an economical shift towards free business
models, often financed by the advertisement industry, the future development of
AR will certainly be affected.

Augmented Reality

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