What is Augmented Reality?Augmented reality (AR) is a live, direct or indirect, view of a physical, real-world environment whose elements are augmented by computer-generated sensory input such as sound, video, graphics or GPS data. It is related to a more general concept called mediated reality, in which a view of reality is modified by a computer. As a result, the technology functions by enhancing ones current perception of reality. By contrast, virtual reality replaces the real world with a simulated one. Augmentation is conventionally in real-time and in semantic context with environmental elements, such as sports scores on TV during a match. With the help of advanced AR technology (e.g. adding computer vision and object recognition) the information about the surrounding real world of the user becomes interactive and digitally manipulable. Artificial information about the environment and its objects can be overlaid on the real world.We may defineaugmented realityto be a real time experience of direct or indirect interaction with the environment of a physical real world that has been augmented or enhanced by the help of computer generated details and adding them to it. AR can be viewed in 3-D real or imaginary platform of objects to interact with. Virtual reality is somewhat difference in the sense that it performs in a virtually created environment while AR is close to the real world.Augmented reality get us the useful information we need immediately before us. It helps in simplifying ones life by providing a sense of reality by superimposing virtual items upon the real world in real time. These virtual items in front of us might get us some information that we cannot detect with our own senses. It helps one perform daily tasks with the help of digital information provided or just have an entertainment purpose with Wikitude or other mobile AR applications.

History195762:Morton Heilig, a cinematographer, creates and patents a simulator calledSensoramawith visuals, sound, vibration, and smell. 1968:Ivan Sutherlandinvents thehead-mounted displayand positions it as a window into a virtual world. 1980:Steve Manncreates the first wearable computer, a computer vision system with text and graphical overlays on a photographically mediated reality, or Augmediated Reality.1981: Dan Reitan geospatially maps multiple weather radar images and space-based and studio cameras to virtual reality Earth maps and abstract symbols for television weather broadcasts, bringing Augmented Reality to TV. 1990: The term "'Augmented Reality'" is believed to be attributed to Tom Caudell, a former Boeing researcher. 1992:Louis Rosenbergdevelops one of the first functioning AR systems, calledVirtual Fixtures, at theU.S. Air Force Research LaboratoryArmstrong, and demonstrates benefits to human performance. 1992:Steven Feiner,Blair MacIntyreandDoree Seligmannpresent the first major paper on an AR system prototype, KARMA, at the Graphics Interface conference.1993: Mike Abernathy, et al., report the first use of augmented reality in identifying space debris using Rockwell WorldView by overlaying satellite geographic trajectories on live telescope video. 1993 A widely cited version of the paper above is published inCommunications of the ACM Special issue on computer augmented environments, edited by Pierre Wellner, Wendy Mackay, and Rich Gold. 1993:Loral WDL, with sponsorship fromSTRICOM, performed the first demonstration combining live AR-equipped vehicles and manned simulators. 1998: Spatial Augmented Reality introduced atUniversity of North Carolinaat Chapel Hill byRamesh Raskar, Welch,Henry Fuchs.[37]1999: Frank Delgado, Mike Abernathy et al. report successful flight test of LandForm software video map overlay from a helicopter at Army Yuma Proving Ground overlaying video with runways, taxiways, roads and road names. 1999: The US Naval Research Laboratory engage on a decade long research program called the Battlefield Augmented Reality System (BARS) to prototype some of the early wearable systems for dismounted soldier operating in urban environment for situation awareness and trainingNRL BARS Web page2000:Bruce H. ThomasdevelopsARQuake, the first outdoor mobile AR game, demonstrating it in theInternational Symposium on Wearable Computers.2001: NASA X-38 flown using LandForm software video map overlays at Dryden Flight Research Center. 2008: Wikitude AR Travel Guide launches on 20 Oct 2008 with theG1 Android phone. 2009: ARToolkit was ported toAdobe Flash(FLARToolkit) by Saqoosha, bringing augmented reality to the web browser. 2013:Googleannounces an open beta test of itsGoogle Glassaugmented reality glasses. The glasses reach the Internet through Bluetooth, which connects to the wireless service on a users cellphone. The glasses respond when a user speaks, touches the frame or moves the head.

Technology in Augmented Reality

It uses computer vision rendering of 3-D virtual items from the exact viewpoint from which the shot of the real environment is being taken by the tracking cameras. This image registrations mostly use video tracking. The process works by tracking the images and then reconstructing them. Tracking makes use of edge detection, feature detection or other to recognize images. In computer vision, the available tracking techniques are of two types, feature based and model based methods. Feature based discovers the connection between the 2-D image features and 3-D coordinates. Model based method uses tracked models like 2-D templates. As the connection is made between 2-D and 3-D frame, the 3-D pose can be made possible to project it on to the 2-D coordinates.The devices for augmented reality are input devices, tracker, computers and displays.In displays, there areHead mounted displays (HMD)Handheld displaysSpatial displays1. Head mounted display is a device worn on the head or as a part of a helmet and that makes users view of his surroundings with images of both real and virtual items.2. Handheld displays are small devices that the user can hold in their hands and through the video-see-through technique, the user can overlay graphics on to the real surroundings and activate sensors like digital compasses, GPS and other. These displays come in the form of smartphones, PDAs and tablets which are portable and present a combination of required CPU, camera, accelerometer, compass, and GPS, all that can be used an AR display device.3. In spatial displays, there are video projectors, optical elements, radio frequency tags, holograms and other technologies to deliver graphical information onto the physical items.Augmented reality systems are classified into five categories which are fixed indoor systems, fixed outdoor systems, mobile indoor systems, mobile outdoor systems and mobile indoor-outdoor systems. These categories allow the user for movement, not constrained to one room and move through wireless system.

Software and algorithms

A key measure of AR systems is how realistically they integrate augmentations with the real world. The software must derive real world coordinates, independent from the camera, from camera images. That process is calledimage registrationwhich uses different methods ofcomputer vision, mostly related tovideo tracking.Many computer vision methods of augmented reality are inherited fromvisual odometry. Usually those methods consist of two parts.First detectinterest points, orfiduciary markers, oroptical flowin the camera images. First stage can usefeature detectionmethods likecorner detection,blob detection,edge detectionorthresholdingand/or otherimage processingmethods.The second stage restores a real world coordinate system from the data obtained in the first stage. Some methods assume objects with known geometry (or fiduciary markers) present in the scene. In some of those cases the scene 3D structure should be precalculated beforehand. If part of the scene is unknownsimultaneous localization and mapping(SLAM) can map relative positions. If no information about scene geometry is available,structure from motion methods likebundle adjustmentare used. Mathematical methods used in the second stage includeprojective(epipolar) geometry,geometric algebra,rotation representationwith exponential map,kalmanandparticlefilters,nonlinear optimization,robust statistics.Augmented Reality Markup Language(ARML) is a data standard developed within theOpen Geospatial Consortium(OGC),which consists of an XML grammar to describe the location and appearance of virtual objects in the scene, as well as ECMAScript bindings to allow dynamic access to properties of virtual objects.To enable rapid development of Augmented Reality Application, some software development kits (SDK) have emerged.A few SDK such as CloudRidARleverage cloud computing for performance improvement. Some of the well known AR SDKs are offered by Metaio,Vuforia,Mobinett AR.Wikitudeand Layar. Applications

The basic types of applications of AR that are used are,1. Commercial and Advertising Commercial and Advertising AR is mostly used by marketers to promote their products with the help of augmented 3-D item pop out or presented in their screens as a real thing so that viewers can better understand it from all angles. Marketers find this promotion as a creative idea of showcasing their products to the customers. For example, the famous car company MINI ran an augmented reality advertisement in several German automobile magazines, in which the reader simply had to go to the website of MINI where the car ad shows up as a 3-D MINI.2. Entertainment and Education Entertainment and Education AR is such a wide area of technology, that it covers entertainment and learning very well. There are greatAR entertainment apps,AR games, and educational apps for learning insmartphones.

3. Medical Medical applications have image guided 3-D view of the human body upon which the user can see the details and learn from it.4. Mobile Applications Mobile apps contain a variety of different apps that can be any augmented character on screen, 3-D navigators to find hotels, restaurants, augmented driving, space AR view, furniture arrangement apps and more like these.5. Military In combat, AR can serve as a networked communication system that renders useful battlefield data onto a soldier's goggles in real time. From the soldier's viewpoint, people and various objects can be marked with special indicators to warn of potential dangers. Virtual maps and 360 view camera imaging can also be rendered to aid a soldier's navigation and battlefield perspective, and this can be transmitted to military leaders at a remote command center. An interesting application of AR occurred when Rockwell International created video map overlays of satellite and orbital debris tracks to aid in space observations at Air Force Maui Optical System. In their 1993 paper "Debris Correlation Using the Rockwell WorldView System" the authors describe the use of map overlays applied to video from space surveillance telescopes. The map overlays indicated the trajectories of various objects in geographic coordinates. This allowed telescope operators to identify satellites, and also to identify - and catalog - potentially dangerous space debrisStarting in 2003 the US Army integrated the SmartCam3D augmented reality system into the Shadow Unmanned Aerial System to aid sensor operators using telescopic cameras to locate people or points of interest. The system combined both fixed geographic information including street names, points of interest, airports and railroads with live video from the camera system. The system offered "picture in picture" mode that allows the system to show a synthetic view of the area surrounding the camera's field of view. This helps solve a problem in which the field of view is so narrow that it excludes important context, as if "looking through a soda straw". The system displays real-time friend/foe/neutral location markers blended with live video, providing the operator with improved situation awareness.Researchers at USAF Research Lab (Calhoun, Draper et al.) found an approximately two-fold increase in the speed at which UAV sensor operators found points of interest using this technology.This ability to maintain geographic awareness quantitatively enhances mission efficiency. The system is in use on the US Army RQ-7 Shadow and the MQ-1C Gray Eagle Unmanned Aerial Systems.6. Navigation:- AR can augment the effectiveness of navigation devices. Information can be displayed on an automobile's windshield indicating destination directions and meter, weather, terrain, road conditions and traffic information as well as alerts to potential hazards in their path. Aboard maritime vessels, AR can allow bridge watch-standers to continuously monitor important information such as a ship's heading and speed while moving throughout the bridge or performing other tasks. The NASA X-38 was flown using a Hybrid Synthetic Vision system that overlaid map data on video to provide enhanced navigation for the spacecraft during flight tests from 1998 to 2002. It used the LandForm software and was useful for times of limited visibility, including an instance when the video camera window frosted over leaving astronauts to rely on the map overlays.The LandForm software was also test flown at the Army Yuma Proving Ground in 1999. In the photo at right one can see the map markers indicating runways, air traffic control tower, taxiways, and hangars overlaid on the video. 7. Industrial design:-AR can help industrial designers experience a product's design and operation before completion. Volkswagen uses AR for comparing calculated and actual crash test imagery.AR can be used to visualize and modify a car body structure and engine lawet. AR can also be used to compare digital mock-ups with physical mock-ups for finding discrepancies between them.

Examples of Augmented Reality appsAugmented Realityan old concept, are not very common words yet, to be very familiar with, but its such a thing that would take us to a whole lot of a different perspective of the world around us with itsaugmented reality apps. It combines 2 words to deal with, augmented means enhanced or increased and reality, which together simply meansenhanced reality. By using hardwares or tools such as our smartphones we can discover such beneficial details in the form of visual data imagery that are not visible to us normally.Augmented reality is such an evolution which adopts new ways to add information discoveries to the reality inlimitless possibilities from fun, games, sports and education to technology in engineering and medicine and more.The listed apps below are there in android / iphone devices to make us understand what it can do with the camera, GPS and other sensors to impress us. Lets say we go to Beijing, a well known city in China. Now we want to find out any vegetarian restaurant there (for example), but as everything is written in chinese which we do not understand, we are unable to find any. That time, we take out our smartphone, connect to the internet and launch an app. This app looks with the rear camera and shows us what us couldnt figure it out in actual view. We point our camera to next to next buildings and it would say non vegetarian restauranthotel.vegetarian restaurant and there we get the right one to get us forward. Now, this is called augmented reality adding information to our reality in many ways. There are not just this type of augmentation but a wide variety of augmented reality apps which use augmented reality.1.AcrossAirPlatform: iOS

Augmented reality browser is an amazing 3D navigator to help us reach our location easily. We hold our smartphone upright and look around with our camera to view restaurants, hotels, landmarks, cinemas and other geotagged entries.Floating image balloons on screen display information of the chosen picture.We hold it horizontally to switch to Google Maps to show our position and pin it to view it later or find our parked vehicle.Integrated with Facebook, Twitter and Flickr and lets us share and store location photos.2.Google GogglesPlatform: AndroidThis amazing Google app uses image recognition technology to deliver information about various logos, landmarks, barcodes or QR codes.Add contacts with business cards, read novel summaries by scanning the title, all by taking its picture.We get the power of Google search engine with our camera.Recognize DVDs, CDs, paintings, books.3.Google Sky MapPlatform: Android

Think of ourself lying relaxed in one starry night under a clear sky, when we spot a constellation, but to know which it would be, point our smartphone camera towards the sky and Google Sky Map will tell us all about that constellation.Point to anything in the sky and we will learn all about it.4.iOnRoad Augmented DrivingPlatform: Android, iOSUltimate road safety app, helps us with navigation on road trips and keeps us safe preventing collision on the roads ahead.Uses smartphone camera , GPS and other sensors to detect for getting off the road or moving too close to another vehicle, by generating an audio-visual warning.Simply mount our smartphone on windshield and iOnRoad starts automatically as we move.It detects when and where we are parked and helps us later to reach our parked car with the navigation and a clicked photo of the parked area.Best augmented reality app in 20115.Wikitude World BrowserPlatform: Android, iOS, Bada, Blackberry, Windows Phone

Smartphone AR encyclopedia.Uses camera to browse at our surroundings and get information on landmarks, restaurants and other places.Find hotels, ATMs with favourite cuisine of ours from Qype, Yelp, Trip Advisor,Hotels.com.Wikitude World Browser is the best augmented reality browser in 2009, 2010 and 2011.6.3D Compass+ ( AR Compass )Platform : Android3D Compass+ gets us together navigation maps, a compass and local business finder apps all into one with an augmented reality view using the camera. It displays a compass on the screen and a map to navigate us through the directions to our desired location.We can adjust the brightness, directly from it for a clear view even in sunlight.7.Augmented Car FinderPlatform: iOSAs name suggests, its a car finder app.Finding our car in a parking lot or at any other crowded areas seems a tough task when were in a great hurry.Augmented Car Finderuses our camera to search for our vehicle and give us directions to it and then shows us the street address closest to our parked car.8.AR InvadersPlatform: iOS, AndroidSave our planet from aliens. Everything around us turns into a warzone where us can point our smartphone anywhere with 360 degree of view to find and shoot space invaders.Our smartphone becomes a window to this augmented reality.Invite our friends in multiplayer mode and recruit an army with them.9.LayarPlatform: Android, iOS, Blackberry

Find services easily anywhere near us with this AR browser of our smartphone.Use camera to scan any building or street corners and Layar will bring us over 3000 layers of digital information to choose from.Layar even displays tweets from nearby areas.Scan magazines and make the print world clickable. Save favourites and share anywhere.10.SpotCrimePlatform : iOS

App byspotcrime.comto show and keep tracks of all the crimes near us or anywhere on the streets of our map. With GPS, it tells us whether we are taking a safe route or not. Point our camera towards a street and check if it is so. It shows us criminal records with different coloured icons for different types.Limitations and the Future of Augmented Reality

Augmented reality still has some challenges to overcome. For example,GPSis only accurate to within 30 feet (9 meters) and doesn't work as well indoors, although improved image recognition technology may be able to help People may not want to rely on theircell phones, which have small screens on which to superimpose information. For that reason, wearable devices like SixthSense or augmented-reality capablecontact lensesand glasses will provide users with more convenient, expansive views of the world around them. Screen real estate will no longer be an issue. In the near future, we may be able to play a real-time strategy game on wer computer, or we can invite a friend over, put on wer AR glasses, and play on the tabletop in front of we.There is such a thing as too much information. Just as the "CrackBerry" phenomenon and Internet addiction are concerns, an overreliance on augmented reality could mean that people are missing out on what's right in front of them. Some people may prefer to use their AR iPhone applications rather than an experienced tour guide, even though a tour guide may be able to offer a level of interaction, an experience and a personal touch unavailable in acomputerprogram. And there are times when a real plaque on a building is preferable to a virtual one, which would be accessible only by people with certain technologies.There are also privacy concerns. Image-recognition software coupled with AR will, quite soon, allow us to point our phones at people, even strangers, and instantly see information from theirFacebook,Twitter,Amazon,LinkedInor other online profiles. With most of these services people willingly put information about themselves online, but it may be an unwelcome shock to meet someone, only to have him instantly know so much about wer life and background.Despite these concerns, imagine the possibilities: we may learn things about the city we've lived in for years just by pointing wer AR-enabled phone at a nearby park or building. If we work in construction, we can save on materials by using virtual markers to designate where a beam should go or which structural support to inspect. Paleontologists working in shifts to assemble a dinosaur skeleton could leave virtual "notes" to team members on the bones themselves, artists could produce virtual graffiti and doctors could overlay a digital image of a patient'sX-raysonto a mannequin for added realism.The future of augmented reality is clearly bright, even as it already has found its way into our cell phones and video game systems.

Acknowledgement1. http://deepknowhow.com/2014/09/24/augmented-reality-guide-to-ar/2. http://deepknowhow.com/2013/04/04/top-20-augmented-reality-apps-for-android-and-iphoneipad-users/3. http://mashable.com/category/augmented-reality/4. http://www.wikipadia.org

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