Mid-Level Descriptors Extraction of Soccer Video with Domain Knowledge

In this paper, we propose a method for two typical mid-level descriptors extraction of soccer video: view type and playfield position. The output reveals high-level structure of the soccer video. After the robust playfield segmentation, we use the grass-area-ratio and the boundary approximate lines between playfield and non-playfield to classify each frame into three kinds of view types according to a series of rules. We then classify frames captured by the main camera into fifteen kinds of positions by two steps: first, we classify the frames into five kinds according to the orientation of boundary lines; secondly, we use lines detection to further determine the specific playfield position. Experiments on three hours soccer videos show promising results.