Augmented Reality Anywhere and Anytime
The Handheld Augmented Reality
Come to ISMAR 2011
LocoBall combines multiple mobile small displays into a larger virtual game area. The idea is inspired by classical tiled display systems, but in this case of LocoBall those displays are mobile used as input devices too. Though not achieving a high resolution, the combination of multiple small handheld displays delivers an appealing possibility to create a quasi continuous display.
LocoBall uses a completely new type of user interface for the well known game concept of Pong. No buttons, stick, pens, etc. are required. The player simply moves his/her panel over the table in order to explore the game game area and to controll the paddle.
The hardware setup is very simple:
Here is how a typical game situation looks like (click for larger version):
The PDAs can be freely moved on the table without any restrictions due to cables
Controlling the Game
The interaction mechanisms are straightforward. Users move the handhelds left and right in order to orient the paddle, which is used to bounce the ball. Hence, there is no button-pressing involved. The whole game is controlled just by moving the handheld, and thus is extremely simple! The paddle itself holds a face with eyes. The eyes are always oriented towards the ball, to provide the user with additional information. This is needed because most of the time, the ball is not seen (…which causes excitement among the players). The ball is actually a "mama ball" with some kiddies following: the kiddies form a comet-like line, providing a nice indication of the ball movement.
The LocoBall project is focused around the idea of using simple and low cost, off-the-shelf hardware to create a game with a tiled display with movable tiles. The software is split into a client part running on the handheld devices (PDAs) and a PC-based server that performs the tracking, data distribution and can run an optional large display for showing the current game state. The server uses a web cam that is mounted above the game board. Natural feature tracking detects the lit displays at sub-millimetre precision using a custom thresholding algorithm followed by a rectangle finder. A 2D homography matrix transforms the detected poses (position and rotation) of the displays into the virtual game space. All detected poses are written into a Muddleware (Wagner and Schmalstieg, 2007) database that is used to distribute the game state as well as static setup data. The client software running on the PDA connects to the Muddleware server via WiFi to read the shared game state and the PDA's current pose and can thereby adapt the camera view into the virtual game world. Consequently the player can freely pan and rotate his/her PDA over the game board always seeing accurately game-board aligned virtual content.
Here's the game from the server's point of view (overhead camera, click for larger version):
The large white square represents the complete game area. The 5 smaller white rectangles are the players' areas in which they can move their PDAs. The centre PDA can be moved by any player. The position of every detected PDA screen is marked with a red rectangle and a red cross in its centre. Green crosses show filtered and corrected positions since some PDAs are only allowed to move along specific paths (for gameplay rather than technical reasons).
Images from Game Sessions
Player controlling his/her paddle (click for larger version)
Two PDAs closely alligned (click for larger version)
Screenshot of Player 2 (click for larger version)
Screenshot of Player 4 (click for larger version)
A first Publication is currently in submission.
The game's novel concept can be best understood watching a video. Please select from below.
A video introducing the LocoBall game in action can be download in two different qualities:
copyright (c) 2014 Graz University of Technology