Spatial assistance systems designed to empower people in smart environments need to perceive their operational environment, recognize activities performed in the environment, and reason about the observed information in order to plan a course of action. Activities performed by humans are spatio-temporal interactions between a subject, objects, and the (potential) group-based context in which they are performed. Activities mediate and develop space and manifest in spatio-temporal interactions of humans with the environment and the artefacts within.
We propose a human-centred activity-theoretic model for the description of activities by their motives and goals. The model itself is grounded with respect to the spatio-temporal interactional characteristics of the activities being modelled. This description serves as a first step towards bridging the gap between sensor readings and high-level reasoning about space, actions, and change within a logic-based commonsense reasoning framework. To illustrate our ideas we introduce a work-in-progress smart meeting scenario, an overarching scenario that provides a developmental basis for the ongoing doctoral research described in this contribution.