1. An image processing system comprising: a plurality of cameras generating images at a site; a memory to store a data structure comprising a plurality of entries, each of the plurality of entries comprising a device identifier element storing a device identifier of one of the plurality of cameras; and a processing device operatively coupled to the memory, the processing device to: detect, in a first image from a first camera of the plurality of cameras, a first matrix barcode of a plurality of matrix barcodes applied to various subjects of the site; decode the first matrix barcode to determine a subject identifier of a subject in view of the first camera; store the subject identifier of the subject in view of the first camera in association with a first device identifier of the first camera in a first entry of the plurality of entries of the data structure; detect, in at least a subset of a plurality of second images from a second camera of the plurality of cameras, a second matrix barcode; determine, for each second image of the subset, a location at the site of the second matrix barcode at a time each second image of the subset was generated; aggregate data indicating the location at the site of the second matrix barcode at the time each second image of the subset was generated to generate field of view data indicating a field of view of the second camera; and store the field of view data indicating the field of view of the second camera in association with a second device identifier of the second camera in a second entry of the plurality of entries of the data structure.