イベント-アクティビティ・モデルに基づくシーン検索における可変的な役割の利用

We have proposed Event-Activity model, which is a data model on movie databases, for retrievals of scenes. The retrieval method based on this model supports three different viewpoints of users; 1) the difference of entities which users focus on, 2) the difference of granularity of composite activities, and 3) the difference of abstract levels in which activities are captured. In this paper, we extend Event-Activity Model to support these differnces among users' viewpoints on entities. We call the categories in which entities are classified variably as roles. Memberships of roles are decided according to the present status of entities. We represent rules of role assignments as statecharts, which are state trasition diagrams for supporting hierarchical structures of states. Each state in statecharts represents a role of entities, and state transitions are triggered by events.