Abstract: Collision phenomenon is an unpleasant issue that needs to be addressed during trajectory rearrangement in video synopsis.It is usually constrained by some collision cost in the final energy function to be optimized.However,most synopsis methods compute the collision cost term repeatedly in the iterative optimization process,leading to serious computation redundancy.To solve that,a novel synopsis method based on spatial relationships between trajectories is proposed in this paper.It turns out whether two trajectories will collide or not can be determined beforehand by analyzing their spatial relationships.Accordingly,three kinds of relationship are defined and corresponding fast computation of collision cost are given.In this way,the redundancy in collision cost computation is decreased and thus improving the speed of traditional methods obviously.Experimental results demonstrate the effectiveness of the proposed method.

Key words: Collision phenomenon, Trajectory rearrangement, Trajectory relationship, Video processing, Video synopsis