High-level representation sketch for video event retrieval

Representing video events is an essential step for a wide range of visual applications. In this paper, we propose the event sketch, a high-level event representation, to depict the dynamic properties of video events composed of actions of semantic objects. We show that this representation can facilitate a novel sketch based video retrieval (SBVR) system, which has not been considered before to the best of our knowledge. In this system, users are allowed to draw the evolutions (e.g. spatiotemporal layouts and behaviors of semantic objects) on a board, and retrieve the events whose semantic objects have the similar evolutions from a database. To do this, event sketches are constructed on both the user queries and database videos, and compared under a novel graph-matching scheme based on data-driven Monta Carlo Markov chain (DDMCMC). To test our approach, we collect a novel dataset of goal events in real soccer videos, which consists actions of multiple players and shows large variability in the evolution process of the events. Experiments on this dataset and the publicly available dataset CAVIAR demonstrated the effectiveness of the proposed approach.