So I am trying to create a passive system (hardware or software) that tracks foot traffic within a space, analyzes each specific "user" and saves it in a buffer. Essentially creating a unique ID for each member walking within the space.

I've mulled over some solutions like RFID, NFC, and blob detection. These solutions I've thought of dont seem to be the best approach due to certain installation constraints.

Wondering if anyone could think of a solution (hardware/software based)