The Fraunhofer Institute for Applied Information Technology FIT just presented an Augmented Reality system for use under water. A diver's mask with a special display lets the diver see his or her real submarine surroundings overlaid with computer-generated virtual scenes. Augmented Reality research has made enormous progress in the last few years, creating many exciting, albeit land-based applications. Now, FIT researchers are the first to demonstrate an AR application designed for underwater use. Submerged use is a major challenge for technical systems. They must be waterproof and robust enough to withstand the high additional pressure of increasing diving depth. FIT researchers built a prototype AR system that meets these requirements. Its main component 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. Thus, a run-of-the-mill indoor pool may be visually upgraded to a (virtual) coral reef with shoals, mussels and weeds.
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More information:
http://www.sciencedaily.com/releases/2009/03/090317095028.htm