AR research has made enormous progress in the last few years, creating many exciting, albeit land-based, applications. We now built a prototype AR system that is waterproof and robust enough to be used in a swimming pool. Thus, a run-of-the-mill indoor pool may be visually upgraded to a (virtual) coral reef with shoals, mussels and weeds.
Main component of the system is a waterproof display in front of a diver’s mask. The display lets the diver see his or her real underwater environment plus additional virtual objects. A camera above the diver’s mask detects underwater markers. Based on distance and angle between the camera and the marker position, an ultra-mobile PC (UMPC) that the diver takes with him in a backpack generates a visually correct representation of the virtual 3D scenes associated with the markers. To make sure that the virtual scenes are still shown in their correct positions if a movement of the diver should hide the markers temporarily, we use a tracker that measures 3-axis angular acceleration plus changes in the magnetic field and the direction of gravity, to follow the diver’s orientation.
As a demonstrator we created the world’s first mobile underwater AR game. It puts the player in the role of an underwater archaeologist searching for a treasure chest. The playground consists of six virtual 'islands' on the sea bed, each with its specific rich marine wildlife. In one of the underwater locations the treasure chest can be found, but it then takes a code number to open the lock. The elements of this number can be found in 'magical' mussels hidden in the other five locations. To put together the code number that opens the treasure chest, the 'pearls' in the mussels must be collected in the right sequence. For this novel underwater game we designed a user interface optimized for the swimming and diving player: It works without any manual interaction devices.
For the player, our game combines the fascinating sensation of weightlessness under water with the fascination of advanced AR technology, creating a unique exciting experience that may become a new special attraction for water parks. For the researcher, our prototype is a robust platform for future development work well beyond entertainment applications. The technology could be used to support professional divers, e.g. in the maintenance of bridges, offshore oil rigs or dams.