Visual Event Classification via Force Dynamics

This paper presents an implemented system, called LEONARD, that classifies simple spatial motion events, such as pick up and put down, from video input. Unlike previous systems that classify events based on their motion profile, LEONARD uses changes in the state of force-dynamic relations, such as support, contact, and attachment, to distinguish between event types. This paper presents an overview of the entire system, along with the details of the algorithm that recovers force-dynamic interpretations using prioritized circumscription and a stability test based on a reduction to linear programming. This paper also presents an example illustrating the end-to-end performance of LEONARD classifying an event from video input.