Study On Key Techniques Of Offside Detection In Soccer Video

In today's soccer matches, the offside is judged mainly by assistant referees. So many foul behaviors occur synchronously in the playfield, it is impossible for referee to always give the proper judgments of offside. However, through computer vision technology, an accurate judgment can be made to amend the assistant referee's miscarriage of justice.The semantic analysis can be focused on the playfield by the playfield detection. Through camera calibration, homography is calculated. The players'position in the image coordinate system is transformed to that in the Euclidean coordinates by homography. After getting the positions, offside detection can be achieved by offside rules semantic reasoning. In playfield detection, the color is represented in HSV color space. The hue value and saturation value are used to find the dominant color, which the value channel is omitted. This approach eliminates the effect of shadow which is brought out by illumination. In order to reconstruct the point on the playfield, playfield digital model should be constructed and line detection should be done in each frame. The across point of the lines are used to calibrated the camera. The most accurate matching means the most accurate homography. Theoretically speaking, the offside can be reasoning if we can detect the location of the ball and players. The offside reasoning rules were designed to accurately judge the offside.Playfield detection algorithm is calculated from contractible image. The experimental results show that this method is of very high accuracy. And the camera can be calibrated accurately if the sufficient conditions are satisfied. So the position of players can be accurately reconstructed and the correct judgment of the offside can be given.