US Patent 9619639 Real-time presence verification

A method for real time presence verification, comprising: capturing a first image of a machine-readable label by a first camera of a mobile device; automatically decoding the machine-readable label to extract a reference to a database entry in response to the capturing; automatically triggering at the mobile device a capturing of a second image by a second camera of the mobile device in response to at least one of the decoding and the capturing; and automatically forwarding the second image and at least one of the first image, the database entry, and the reference to a control network node for documentation of the second image in association with the database entry.