Note that this isn't all that dissimilar to Xandem's tomographic motion detection. Their "Xandem Home" product makes a Harry Potter Marauder Map style overlay on a map of your home showing where all moving people are in realtime. It is really cool stuff that I'm about to have installed in my own home:

http://www.securityelectronicsandnetworks.com/articles/2014/...

http://www.xandem.com/motion-detection

Compared to crappy PIRs from companies like ADT, it is great stuff.