While it may be some time before you buy a device like SixthSense, more primitive versions of augmented reality are already here on some cell phones, particularly in applications for the iPhone and phones with the Android operating system. In the Netherlands, cell phone owners can download an application called Layar that uses the phone's camera and GPS capabilities to gather information about the surrounding area. Layar then shows information about restaurants or other sites in the area, overlaying this information on the phone's screen. You can even point the phone at a building, and Layar will tell you if any companies in that building are hiring, or it might be able to find photos of the building on Flickr or to locate its history on Wikipedia.
Layar isn't the only application of its type. In August 2009, some iPhone users were surprised to find an augmented-reality "easter egg" hidden within the Yelp application. Yelp is known for its user reviews of restaurants and other businesses, but its hidden augmented-reality component, called Monocle, takes things one step further. Just start up the Yelp app, shake your iPhone 3GS three times and Monocle activates. Using your phone's GPS and compass, Monocle will display information about local restaurants, including ratings and reviews, on your cell phone screen. You can touch one of the listings to find out more about a particular restaurant.
There are other augmented reality apps out there for the iPhone and other similar phones -- and many more in development. Urbanspoon has much of the same functionality as Yelp's Monocle. Then there's Wikitude, which finds information from Wikipedia about sites in the area. Underlying most of these applications are a phone's GPS and compass; by knowing where you are, these applications can make sure to offer information relevant to you. We're still not quite at the stage of full-on image recognition, but trust us, people are working on it.
We've looked at some of the existing forms of augmented reality. On the next page, we'll examine some of the other applications of the technology, such as in video games and military hardware.