Abstract: A counting device bears a visually distinct pattern or marking, and is coupled to a pusher or other movable system of a shelf in a manner that causes the counting device to rotate in response to changes in position of the pusher. When items are placed on a shelf, or removed from the shelf, causing the pusher to move, the pattern on the counting device rotates at an angle defined by an extent of the movement of the pusher. Images captured of the counting device at various times may be processed to determine orientations of the pattern at such times. Where a change in an orientation of a pattern is detected, a number of items added to or removed from a shelf may be calculated based on the change in orientation and an event involving the number of items may be determined to have occurred.

Abstract: A multi-interface apparatus includes a crossbar to which a plurality of accessories using different mechanical interfaces may be attached and detached. Accessories such as wire hooks, shelves, bins, and so forth may be used. The different mechanical interfaces may include slatwall, pegboard, and saddle mount. Multiple accessories with different types of mechanical interfaces may be supported simultaneously by the crossbar. The crossbar may be instrumented. For example, load cells may be used to determine the weight on the crossbar.