Content-trajectory approach for searching video databases

In the past few years, modeling and querying video databases have been a subject of extensive research to develop tools for effective search of videos. In this paper, we present a hierarchal approach to model videos at three levels, object level (OL), frame level (FL), and shot level (SL). The model captures the visual features of individual objects at OL, visual-spatio-temporal (VST) relationships between objects at FL, and time-varying visual features and time-varying VST relationships at SL. We call the combination of the time-varying visual features and the time-varying VST relationships a Content trajectory which is used to represent and index a shot. A novel query interface that allows users to describe the time-varying contents of complex video shots such as those of skiers, soccer players, etc., by sketch and feature specification is presented. Our experimental results prove the effectiveness of modeling and querying shots using the content trajectory approach.