To develop the blind football play-by-play system for the visually impairment spectators mentioned above, we considered the concept of the system and thought about an input method and an output method (see Fig. 1). The input method should correctly detect the position of players and the output method should effectively display the information to the spectator(s). As an output method, a synthesized voice and/or a refreshable tactile display have a possibility to be effective. From the viewpoint of realizing an automatic live coverage, voice explanation is the final goal though, tactile display is easy to utilize in these days. We can use a consumer version device by KGS Corp., which is spread in Japan and it is already shown that the blind can understand many graphical information using it .
As an input method, we tried to consider the possibility of using a camera and GPS system to detect the position of the players. If we use cameras with image processing system, these players do not need to wear special devices. However, the position of the camera should be high enough to capture the entire field at once and setting a tall pole to carry the camera might be dangerous and difficult to establish in local game. On the contrary, GPS system forces players to wear some hardware but to prepare the total system will be easier than the camera system.
Of course, the combination of the camera system and the GPS system should be perfect though, we decided to start a basic study to find the possibility to use a GPS system as a first step, since we can use the Quasi-Zenith Satellites System (QZSS) around Japan with low cost. The QZSS is a national project to make GPS information more precise. It is composed of four satellites and their trajectories are always and almost on the top of the field around Japan. The fourth satellite launched in October 2017 and full-service will start from fiscal year 2018 .