Augmented reality (AR) refers to computer displays that add virtual information to a user s sensory perceptions. Most AR research focuses on see-through devices, usually worn on the head that overlay graphics and text on the user s view of his or her surroundings.
In general it superimposes graphics over a real world environment in real time.Getting the right information at the right time and the right place is key in all these applications. Personal digital assistants such as the Palm and the Pocket PC can provide timely information using wireless networking and Global Positioning System (GPS) receivers that constantly track the handheld devices. But what makes augmented reality different is how the information is presented: not on a separate display but integrated with the user s perceptions. This kind of interface minimizes the extra mental effort that a user has to expend when switching his or her attention back and forth between real-world tasks and a computer screen. In augmented reality, the user s view of the world and the computer interface literally become one.