Identifying Geographical Position inside a fully enclosed building

Hey Guys,
I am doing a project on how to id and locate people inside a huge building within a metre or less and display their position including their relative vertical height i.e. which floor the person is.If it was technologically feasible it could be used to locate prisoners in a jail(One possible application)..As GPS wouldn't be good inside a building,that left me with rf id tagging and wifi(??) both which i searched in Google but came up with very little further information..Looks like either the technology is in itz infancy or i can't really google up things:sshhh: Anyway if u guys can find some technology to actually locate people accurately..do reply..expecting Reply from all CEANS out there..!!!😁