Because travellers in the airport terminal are indoors, they can't use GPS to position devices, so the app instead uses triangulation and signal strength between the terminal's wi-fi hubs. The augmented reality app only works when wi-fi is activated on the iPhone, although the smartphone doesn't need to be connected to a wi-fi network.

Copenhagen Airport was seen as particularly suitable for the augmented reality app because the large number of wi-fi hubs in the terminal made the locating of devices relatively easy.

The team from Sita spent between three and four months working out how to locate devices using the airport's wi-fi infrastructure before spending two to three months building the augmented reality platform itself.

The augmented reality application allows users to plan their time in the airport by helping them locate shops, restaurants and other services according to their search preferences.

According to Copenhagen Airport IT director Christian Poulsen, the airport is always trying to improve the passenger experience, and the augmented reality application provides a new dimension for travellers.

The system - which was developed by Sita's research group Sita Lab with the help of the airport IT team and apps developer Novasa - uses a database of points of interest with the relevant information being relayed to the device depending on its location.

One of the benefits of the app over old-style physical maps is that any changes in shops or terminal layout can be quickly and cheaply changed in the database used by the software.

The application updates its location every six seconds and the system is accurate to 5m in most parts of the airport and to 3m in some areas, according to Sita Lab innovation manager Stephane Cheikh who managed the augmented reality project.

The augmented realty application can be viewed in landscape or portrait mode, shown above, on the iPhone.

Another function of the augmented reality app is to locate departure gates, which are located on four different arms at Copenhagen Airport. The user simply searches for their gate and the app tells them how far away it is and which way they need to move using a radar circle, shown at the top right of the screen.

The augmented reality application is an upgrade to Copenhagen's existing iPhone app, shown above, which has been downloaded more than 100,000 times. Most users who have been to the airport since the augmented reality element was added have upgraded the app through iTunes, according to Sita Lab's Cheikh.

The basic app provides passengers with live data, such as arrivals and departures, as well as advertising for airport services.

The original iPhone app also shows information about when passengers need to go to their gates or if flights are delayed.

Sita Lab is waiting to see how the augmented reality app is received by users before looking at introducing it at other airports. If feedback is good, the company will look into developing the technology for the iPad 2 and Android devices.

Further uses of the augmented reality app being considered by Sita Lab include making travellers aware of special offers available at certain locations in the airport and alerting passengers when their flight is about to leave.