Experience of Immersive Virtual World Using Cellular Phone Interface

The cellular phone has become a popular portable information device. In this study, the i-mode of the cellular phone was applied to the interface with the immersive virtual world. By using the cellular phone interface, the user can experience the immersive virtual world easily using his own device. The interaction using the i-mode was experimentally evaluated in the walk-through application. In addition, by integrating the cellular phone interface with the transparent immersive projection display, an invisible immersive interface that enables the user to experience the virtual environment in the real work place was constructed. This system was applied to several fields of application such as the visualization of data and the telecommunication. environment in the real world, by integrating the transparent display system with the cellular phone interface. This paper describes the system construction, the features and several applications of the immersive environment using the cellular phone interface. 2. Cellular Phone Interface 2.1 Features of Cellular Phone Device In order to experience the high presence virtual world using the immersive projection display, the user must operate the graphics workstation to run the application program and interact with the virtual world using the special interface devices. For example, in the CAVE developed at the University of Illinois, the wand and the wanda are used for the interface devices. In the case of the CABIN developed at the University of Tokyo, the Nintendo64 Controller, the VibroPointer, and the Twiddler are used for the joystick, the haptic pointer and the character input devices respectively [4][5]. In particular, it is difficult to input characters in the three-dimensional immersive virtual environment. Although the practiced user is able to input characters rapidly using the Twiddler by one hand, it is hard for the unfamiliar user to use this kind of device efficiently. Therefore, it is desired that the everyday device that is carried in the daily life should be used for the interaction so that a large number of people can experience the immersive information space easily. On the other hand, the recent cellular phone has been used to access Internet, and the cellular phone device itself has several functions. For example, the dial button can be used to input characters as well as to dial telephone numbers, and the LCD is used to display information. The pager motor is often installed to inform the phone call using the vibration sensation, and it can be used to display haptic information. In addition, the cellular phone device that is equipped with the Internet access function such as the imode or the WAP (Wireless Application) can be used to transmit data to the computer as a kind of computer terminal. Therefore, we can consider that the cellular phone that is used in the daily life can be used as an interface device with the virtual world effectively. 2.2 i-mode Interface In this study, an interface technology using the i-mode was developed to interact with the immersive virtual world. The i-mode is an Internet access service for the cellular phone provided by the NTT DoCoMo Inc., and the user can access web information using the dial button and the LCD [6]. Currently, in Japan, about twenty-three million people are using this service, and it has become a popular portable information device. The i-mode was applied to realize the interactions such as the walk-through and character input in the virtual world. In these interactions, the dial button of the cellular phone is used for the button and the keyboard functions. Since the LCD is also equipped on it, the user can perform the input operation in the local feedback, without displaying the three-dimensional input window or the menu in the virtual world. In addition, the cellular phone device can also be used as a pointing device by attaching the position tracker to it. In this system, a Polhemus electromagnetic sensor was used to track the position of the cellular phone. In this case, when the cellular phone communicates with the Internet, it generates an electromagnetic wave that causes a tracking error. Therefore, the position tracker was attached about 8 cm away from the body of the cellular phone to reduce the influence of the electromagnetic wave as shown in figure 1. 2.3 Software Construction The i-mode interface is used both as a computer terminal to start the virtual reality application and as an interface device to interact with the virtual world in the application program. Figure 2 shows the software construction of the i-mode interface. In order to start the virtual reality application program, the user first accesses the graphics workstation through the DoCoMo i-mode Center. The application program runs when the user selects the menu item or inputs the name of the application in the imode web page. This i-mode page is written in CGI (Common Gateway Interface), and it runs the shell script to start the application program. By using this method, the user can start the virtual reality application without using a computer terminal. After starting the application program, the CGI program moves to the interaction imode page. When the user inputs characters or selects menu item in the interaction iFig. 1. Cellular Phone Interface with Position Tracker Fig. 2. Software Construction of the i-mode Interface i-mode access page CGI program Application menu Interaction menu User selection User interaction Shell script