| 摘要 |
There is provided an apparatus for detecting when a subject has exited an item of furniture which has an upper side for supporting a subject and an underside opposite to the upper side, and comprises an overhanging component that extends from the underside toward a surface on which the item of furniture is resting. The apparatus comprises a light source to illuminate an edge-feature associated with a distal edge of the overhanging component, to create a shadow of the edge-feature on a region of the surface. The apparatus further comprises a camera arranged to capture sequential images of the region of the surface; and a processing unit. The processing unit is arranged to receive the images; detect an edge of the shadow in each of the received images, detect, in the received images, the appearance of a feature contiguous with the shadow edge; monitor how a detected feature changes over a time period; determine whether a change to the detected feature satisfies at least one predefined criterion for a subject exit event; and output a signal based on the determining. |
