Blair MacIntyre, a professor at Georgia Tech's Augmented Environment Labs explains, "The key to many AR applications is that the information is registered (i.e., aligned) with the view of the physical world. To overlay graphics (or sound) correctly on the view of the world, the computer (or phone) needs to know precisely where the world is in relation to the camera. The more accurately the position and orientation of the device is known, the more accurately the graphics and the physical world can be combined."
That's easier said than done, continued MacIntyre, "On a smart phone, you can try and use the GPS and other sensors (e.g., compass, accelerometers) to estimate the position and orientation of the phone relative to the world; the problem is that the limited accuracy of those sensors restricts the capabilities of these applications."
For example, said MacIntyre, "I have been showing a video I made of one of the 'information browsing' systems on the iPhone, where I look around the courtyard in front of my building, and none of the labels align with the businesses they are referring to. This is not a bug in the application; it's a limitation of the accuracy of the GPS, and is common to all GPS-based AR applications on mobile phones today."
Sean Everett, co-founder of the mobile application marketing firm Evolyte agrees. "The iPhone's GPS and location tracking software is currently not powerful enough to pin-point locations down to a foot or so. If it was, you could imagine walking past a retail store and your phone buzzing you that there was a pair of jeans for sale in your size 6.5 feet inside the door and 8 feet to the right, bottom shelf, 3rd from the bottom. Or you could imagine real-time reservations popping up requesting you to eat at a restaurant you were walking by (say goodbye to the hostess)."
Google thinks it has an answer -- a new barcode system called Moseycode. With it, anyone can place Moseycodes on whatever they want and a Moseycode aware application can then 'read' its information. Once this 'bridge' between reality and its corresponding Web-based information is made, it would be simple to find Everett's jeans.
A screen-grab of Moseycode in action
There are no standards yet for augmented reality applications. The closest we currently have is the W3C's draft Geolocation API Specification. So, for now, the AR applications tend to be one-offs, but Google's move may quickly standardize how they work.
Google isn't the only one trying to bring rhyme and reason to this quickly expanding field. Augmented reality company Mobilizy is attempting to bring order to AR browsers with an HTML-style standard language for augmented reality called ARML (Augmented Reality Mark-up Language). As Rice, chairman of the AR Consortium, observed "Companies are beginning to turn away from the novelty and focus on building an industry."
Augmented reality today
At this point, augmented reality applications are works in process. You can find the most AR applications for advanced smartphones like the HTC T-Mobile G1 handset, which runs Google's Android OS, and the iPhone. Perhaps the most advanced of these applications is SPRXmobile's Layar Reality Browser 3.0. This application superimposes an AR browser over the phone's camera view and presents you with layers of information about the immediate area. You can pan your cell phone camera around and see nearby buildings and spaces tagged with information drawn from Web sources such as Flickr, Wikipedia, and Yelp.