Patent ID: 8811666

Claim:
A video analysis method for identifying a characteristic motion in a video sequence from a plurality of trajectories each indicating movement of features over said video sequence, said method comprising determining said plurality of trajectories, wherein determining said plurality of trajectories comprises: identifying points of interest in each frame of said video sequence; determining, for each frame other than said first frame, at least one point of interest that corresponds to a point of interest in the preceding frame in said video sequence; and constructing a plurality of trajectories for a point of interest in said first frame, each trajectory comprising a location in said first frame and at least one of said following frames of said video sequence, said location in said first frame being the location of said point of interest in said first frame, said location in said at least one following frame being determined by sequentially considering each following frame of said sequence where at least one trajectory extends to the preceding frame and including in that trajectory the location of the point of interest that corresponds to a point of interest in the preceding frame included in the trajectory; determining a first trajectory and a second trajectory from said plurality of trajectories, wherein an indicative relationship exists between said first trajectory and said second trajectory; and classifying said first trajectory and said second trajectory as corresponding to said characteristic motion.