ARShooter is an indoor multiplayer game for your mobile device which closely resembles a simulated paintball match. It is comparable to games such as Laser Tag or Quest as well as a real life version of Counter Strike. Two or more people become each others shootable targets in any given environment, last man standing wins the game. The mobile phone acts as a weapon while simultaneously operating as a viewfinder through which AR-objects, such as health packs and ammo can be seen. For the game each player holds an Android operated mobile phone while an Android application is used to shoot by pointing your phone in a certain direction and tapping the screen. The application shows the players current status displaying information about health, gun in use etc. on the screen of the mobile phone. Unfortunately the game is currently not market ready and as for now only a concept being tested.
To locate the position of the players in the playing field Microsoft Kinect is used. At the time of writing the Kinect Sensor only has a range of four meters with a viewing angle of approximately 90 degrees. This means that the playing field is very small. Another problem is that players cannot circle around each other because the kinect sensor loses the skeletons of both players when one player stands between the sensor and the second player. To enable both, a bigger playing field and a solution to the problem of players moving around each other, more than one Kinect sensor has been used. The sensors have to be placed in different angles and positions so that when a player stands between one sensor and the second player, at least on other sensor sees both players without any obstructions. It was a challenge to connect these technologies, Android, server and Kinect. The Kinect SDK didn’t provide any technology to combine the data from multiple sensors and no other project existed prior to ours, so we had to develop, implement and test our own system. The Kinect sensors are connected to a PC workstation in which one PC per Kinect is preferable. The main PC runs the game server to which all devices are connected via network. For each additional sensor the Kinect client application has to be started and configured.
The fragmentation of Android created some problems by introducing bugs only on certain devices but not on others. It’s the first time any number of sensors can be used to create a bigger playing area and it’s the first time where multiple phones and Kinect sensors are combined to create a game. The game is still a prototype and a study case of what could be an ARShooter game in the close future. The biggest challenge currently is to combine the data from multiple sensors accurately. The setup process has to be very accurate. Just one degree difference in the setup of the angles results in deviations up to 40cm in the position of a player.
It is unclear on how the sensor technology will advance with newer Kinect sensors. A new Kinect sensor is rumored to be released within the next couple of months with a possibly better resolution resulting in enhanced range.