Understanding observations of interacting objects requires one to reason about qualitative
scene dynamics. For example, on observing a hand lifting a can, we may infer that an
“active” hand is applying an upwards force (by grasping) to lift a “passive” can. We present
an implemented computational theory that derives such dynamic descriptions directly from
camera input. Our approach is based on an analysis of the Newtonian mechanics of a
simplified scene model. Interpretations are expressed in terms of assertions about the …