Mah-Jongg
Collaborative Gaming in Augmented Reality
Project duration: 1998-
Contact: Zsolt Szalavári 

Description
 We have developed Mah-Jongg as an augmented game for multiple users, that allows players to play with each other, while the computer is only a high-quality supporting tool. Players are sitting around a common table. Everyone is equipped with a see-trough HMD and a pair of interaction devices - the Personal Interaction Panel. The game engine takes care of start-up and basic game rules. During the game players are supported with a high level automatic privacy system, an augmented help system and the social communiacation with other players. 
Application
 Mah-Jongg is a very old traditional Chinese game, with roots going back into the dust of ancient centuries. In the beginning it’s been only played by emperors and those in the know, because it’s secret. Later public got access to it, and in our century it become popular around the world. The high number of enthusiastic players developed many variants of the game, yet the basic rules are still kept.
We have selected Mah-Jongg as the major implementation example of our concepts on augmented gaming, because it is known world-wide, the main rules are easy to understand, and many of our system features can be presented with it. 
Problems
 Current hardware limitations are not convincing for players to change from traditional games to computer based virtual or augmented games. We have to develop methods for better performance, easier manipulation and last but not least techniques to support "fun". 
Approach
 Mah-Jongg is based on a unique hardware set-up designed to diplay customized information for collaboration of different users in an augmented reality environment.
Face snapping mechanisms ease manipulation of game tiles and help to overcome the limited precision of the input devices both in the absolute and the two-handed relative frame of reference of the common table.
A powerful automatic privacy combined with layering mechanism takes care of sequrity management. Thus player clients render customized versions of the common scene graph with only a single player_id identification. Using this mechanism additional help information is integrated on demand in specific views. 
Publications
 

Movies

  
Movie demonstrating all the properties of our Mah-Jongg game described below.

Good version (AVI 320×240, 12MB), Small version (AVI 160×120, 2MB)

  
 

Snapshots
The hardware setup shown in the left image is composed out of stereoscopic see-through head-mounted displays (HMDs) and Personal Interaction Panels for each player. Every device is tracked in position and orientation by a magnetic tracking system.
The augmentation overlay which is rendered and presented in the see-through HMDs.
Grouping:
  • A tile is grabbed with the pen. Manipulation with the pen is very natural and done directly in 3D space. By moving the tile near to a surface (in this case the panel), a snapping mechanism constrains the motion of the tile to the plane.
  • Moving it close to another tile snaps both tiles together to form a group.
  • This action triggers semantics to insert the help-shovel showing additional help information. In this case the name of the combination is displayed.
Privacy: The same situation during the game seen by two different players. Characters on the opponent’s tiles, as well as help information is not shown. To keep a consistent augmentation, tiles are not hidden entirely from other players. This would cause unexpected popping artifacts during region transition actions.
Private help expressed as a shovel. This additional handle helps to manipulate groups together. The same situation with another players rights is shown in the lower image, i.e. private help information is hidden in his view.
This page is maintained by Zsolt Szalvari. It was last updated on March 1, 2000.
If you have any comments, please send a message to zsolt@cg.tuwien.ac.at.