In this world, the monsters first teach the kids the moves that make up the monster dance and the monsters then complement the kids when they do a good job. We chose these moves because they would be fun for the participants and because they also let us demonstrate a few different recognition techniques using computer vision. All of the vision processes use background subtracted images which contain only a silhouette of the person.
Background subtraction removes the room from the imagery, leaving only the image of the person.
Since it may be difficult to remove shadows induced by strong lighting, shadows have been incorporated into the models. Each of the real-time approaches for recognition described below are run in parallel as the kids perform dance moves. If one method matches well and matches better than the other methods, the system will detect the dance move. The first and simplest technique, for detecting crouching, uses the shape characteristics of the background-difference blob. If the elongation of the blob changes significantly, the algorithm will signal that a crouch has taken place.