Abstract
This thesis presents a technique to efficiently index and retrieve video clips in terms of motion-trajectory-based similarity. We describe a motion trajectory in three representations: the horizontal and vertical movements of the trajectory, and the motion trail that indicates shape of the trajectory. Each representation is approximated by a polynomial function, and the polynomial coefficients are then indexed for retrieval. To measure the matching distance, we combine different spatio-temporal characteristics to provide flexible retrieval processes. In addition, we also proposed a multiscale mode to improve the retrieval efficiency. A unified framework is developed to deal with various query types: query-by-example, query-by-sketch, and query-by-specification. We have performed many experiments to confirm the effectiveness and efficiency of our method. Experimental results indicate satisfactory performance of our work.