Patent attributes
A projected image item tracking system that analyzes projected camera images to determine items taken from, placed on, or moved on a shelf or other area in an autonomous store. The items and actions performed on them may then be attributed to a shopper near the area. Projected images may be combined to generate a 3D volume difference between the state of the area before and after shopper interaction. The volume difference may be calculated using plane-sweep stereo, or using convolutional neural networks. Because these methods may be computationally intensive, the system may first localize a change volume where items appear to have been displaced, and then generate a volume difference only within that change volume. This optimization results in significant savings in power consumption and in more rapid identification of items. The 3D volume difference may also indicate the quantity of items displaced, for example from a vertical stack.