21-02-2012, 10:56 AM
wireless networking and Global Positioning System (GPS)
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INTRODUCTION
Augmented reality (AR) refers to computer displays that add virtual information to a user’s sensory perception. 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 make 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.
1.1 Comparison between AR and virtual environments
The overall requirements of AR can be summarized by comparing them against the requirements for Virtual Environments, for the three basic subsystems that they require.
1. Scene generator : Rendering is not currently one of the major problems in AR. VE systems have much higher requirements for realistic images because they completely replace the real world with the virtual environment . In AR, the virtual images only supplement the real world. Therefore, fewer virtual objects need to be drawn, and they do not necessarily have to be realistically rendered in order to serve the purposes of the application.
2. Display devices: The display devices used in AR may have less stringent requirements than VE systems demand, again because AR does not replace the real world. For example, monochrome displays may be adequate for some AR applications, while virtually all VE systems today use full color. Optical see-through HMD’s with a small field-of-view may be satisfactory because the user can still see the real world with his peripheral vision; the see-through HMD does not shut off the user’s normal field-of-view. Furthermore, the resolution of the monitor in an optical see-through HMD might be lower than what a user would tolerate in a VE application, since the optical see-through HMD does not reduce the resolution of the real environment.
