US Patent 10384869 Optical item management system

An item stowed at an inventory location may rest on a surface such as a shelf or may be supported above the surface. The item may exhibit a footprint that is representative of a physical perimeter of the item. For example, the footprint may be an edge of a shadow cast by the item. Information about a size and shape of a footprint associated with a particular item may be stored. An optical sensor array may acquire sensor image data indicative of the footprint of one or more of the items stored at an inventory location. A quantity of items at the inventory location may be determined by comparing the sensor image data with the stored data.