Tracking inventory items in a store for identification of inventory items to be re-stocked and for identification of misplaced items

A method for tracking inventory items is provided. The method includes using sensors to produce respective sequences of images of corresponding fields of view, the field of view of each sensor overlapping with the field of view of at least one other sensor. The method includes dividing the area of real space into cells having volume and coordinates in a real space, and identifying inventory items and their locations in three dimensions using the sequences of images produced by at least two sensors having overlapping fields of view. The method includes, in response to the identification of the inventory items: (i) matching locations in three dimensions of identified inventory items with cells in the plurality of cells, and (ii) determining, for a particular inventory item matched with a particular cell, whether a count of the particular inventory item is below a threshold for re-stocking the particular inventory item.