One more idea to locate someone or something in a large enclosure

There are many map apps supported by GPS that helps you figure out where you are or where you want to go. The World is shrunk to the size of your  smart phone and you can pretty well figure out by just a few clicks.

However, there are places where you cannot locate objects/people inside a enclosure by just GPS such as inside buildings, big box businessess like SAM's Club, Costco,etc.; museums, exhibititions and convention centers like Javit's in New York and many, many places.

This Finnish company IndoorAtlas has come up with a unique solution by providing a positioning service powering location-based app.
It is hardware agnostic;
works on iOS and Android phones;
Cloud-powered (what is not these days);
and accurate.

It uses unique magnetic signature of a building (steel reinforced) and the resulting distortion of the Earth's magnetic field. This distortion would be specific to a geo-position as well as the structure that distorts this field. In a way it provides a floor plan of a building which you can easily map as Geometrical data-type. Once this is done navigation can be done with an app that you run on the smart phone.

However one has to get the details of a building's magnetic fields to use the app.

Here is a demo video from IndoorAtlas on YouTube.



Read more here.