Hidden extras

Augmented reality (AR), the physical world we can touch and feel mixed with computer-generated imagery, has been called 'mildly terrifying'.

Essentially an optical illusion, AR is a 'sixth-sense' hybrid of real and virtual worlds, where the physical and digital co-exist and interact in real time. With an AR headset, information about streets, buildings, areas and the objects they are home to can be displayed as a data layer superimposed on the wearer's real-world view.

Like so much technical wizardry, AR was foreshadowed by science fiction. It is featured in Terminator and Star Trek, in which the Emergency Medical Hologram programme generates an artificial doctor when a human medic is unavailable. It also surfaces in the William Gibson novel Spook Country. 'Geohacking', as Gibson calls it, appears as GPS-governed 3D graphics that mesh with real-world landscapes.

Despite seeming futuristic, AR could have some fairly prosaic applications; it could be enlisted to virtually rebuild lost historic edifices and simulate planned construction projects; or render virtual objects for museums, exhibitions and theme parks. AR has military (fighter pilots and tank drivers are familiar with the concept) and emergency-services potential, and, what's more, it is accessible.

Augmented reality does not necessarily need clunky goggles to work; the iPhone, Nokia and Android operating system-based mobile handsets could all host AR applications.

In June, Dutch 'strategic creative consultancy' SPRXMobile introduced what it claims to be the world's first AR-based Web browser, Layar, for Android-compatible mobile devices. The browser, which was available in the Netherlands before being rolled out to the rest of the world in August, works on mobile phones with camera, GPS and compass functions, such as the Android-based HTC Magic.

Layar displays real-time digital information on top of what is seen through the camera lens of a phone. Partners, such as Wikipedia or local stores, provide location co-ordinates and relevant information. With content layers programmed, a user can look at the camera screen and see an augmented view of the scene ahead of him: blinking dots on flats that are for sale, and their price, for example; pull-down reviews of side-street bars; the position of ATMs; places with jobs going; and, with a scary stalker-type application, the location of individuals.

Other frills include Gibson-style 'geotagged' photographs enhanced by geographical identification 'metadata'.

AR seems devilishly clever but Layar may be a layer of information too far for many. We already have our heads in the digital clouds and may feel close to information overload. More data could lead to befuddlement or even disaster; imagine the dangers posed by drivers whose attention is constantly being diverted by Spook Country-style signs.

Resistance towards AR will probably fade, though, because, unlike 3D, it is useful; a roaming technology 'fab app'.