5. Analysis of the Videos and Extracted Features

Inspection of tapes showed that producers of videos use a main camera to follow the action of the game; since game action depends on the ball position, there exists a strong correlation between the movement of the ball and camera action. The main camera is positioned along one of the long sides of the playing field. In Figure 5.13 some typical scenes taken with the main camera are shown.

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Figure 5.13: Example of frames taken from the main camera.

Identification of the part of the playing field currently framed and camera action are among the most significant features that can be extracted from shots taken by the main camera; these features can be used to describe and identify relevant game events. Typical actions featured by the main camera are: i) pan, ii) tilt and iii) zoom. Pan and tilt are used to move from a part of the playing field to another one, while zoom is used to change the framing of the subject.

Highlights that we have elected for thorough investigation are: i) forward launches, ii) shoots on goal, iii) turnovers, iv) penalty kicks, free kicks next to the goal box and corner kicks. These are typical highlights shown in TV news and magazine programs summarizing a match, even if these actions do not lead to the scoring of a goal. Moreover, penalty kicks and corners are often used to calculate statistics for a match. All of the above highlights are part of attack actions taking place in the goal box area, and are therefore strictly related to goal actions. It must also be noted that for each of the above highlights there exist two different versions, one for each playing field side. The system that we present can discriminate each case.