gshegosh writes: "We have been approached by a customer that needs positioning inside their factory which is about 5000 square meters big. They require 30cm precision. What options are there if it comes to ready-to-use products? We've been considering WiFi fingerprinting but it seems it doesn't have enough precision, using RFID in turn demands putting a few dozen thousand tags all around the factory. Have you heard of any solutions to this problem?"