handheld augmented reality

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Project is supported by the
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Augmented Reality Games

Cows vs. Aliens 2007


This project was developed by Alessandro Mulloni as part of his master thesis.

>> Download the full-res video, encoded using the DivX codec <<

Concept. This is a multi-player game where players are divided into two competing teams. The game setting is a group of locations which are pastures where cows are quietly grazing; there are also two special locations where a stable for each team is located. Adjacent locations are connected to each other and form a graph. Cows are not aware of the fact that an alien invasion is currently taking place and have o chance to survive without the help from players; UFOs are present on some of the locations and they are ready to shoot any cow that will try to run from that location.

Setup. The real environment where the game takes place must be set up with a number of fiducial markers positioned on walls. Such fiducial markers naturally form a graph of real locations that are interconnected to each other by line-of-sight and physical adjacency relationships. The virtual game environment is directly mapped onto the real world; each real location (a marker on a wall) represents a virtual location of the game environment, while line-of-sight relationships are mapped on virtual interconnections between game locations. The interaction between players and the game environment is then mediated by the mobility gameplay elements: players are forced to physically move inside the real environment to reach specific real-world locations before any game action can be issued on the corresponding virtual game locations. Using the Studierstube ES framework, 3D game entities are registered in 3D and superimposed on markers through the display of handheld devices. The augmentation of real-world locations with computer-generated content helps giving all players the impression that they are physically visiting the game environment and its virtual locations.

Gameplay. The final goal of the game is to save as many cows as possible; cows can only be considered safe when they are located inside a stable: the goal of players is to collect cows from around the game space and to take them safely to the stable that belongs to their team. Players can command cows to move between connected locations (any pasture can hold a maximum of four cows). Cows should try to avoid facing UFOs otherwise they might not make it alive to the stable; any UFO in a location can in fact be commanded to shoot all the cows which are present in the same location. A secondary goal of players is therefore to prevent the opponents from bringing cows to their stable by obstructing them with the aid of UFOs. The winner of the game is the team that saves the most cows.

AR Game Design

  • Multi-user system, focused on user mobility and location-awareness
  • Collaborative and competitive user behaviours using Augmented Reality
  • Public and private views, knowledge is shared between players from the same team
  • Exploit both locations and line-of-sight connections between locations
  • Physical setup easy to build in other environments


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