With Tango, Google is now equipped to map the entire world -- inside and out - CNET

It takes >= 2 to Tango; also see Google's Tango site

"The initiative, previously called Project Tango, is Google's ambitious plan to map the indoor world. Google Maps is already wildly popular, with more than 1 billion users. But where Maps is a cartographer's dream on steroids, Tango isn't concerned with streets and rivers and national parks. Tango is for everything underneath rooftops: hallways, offices, ballrooms and -- perhaps more importantly for Google's advertising ambitions -- the stuff inside those rooms, like furniture and products on shelves.

On Thursday, the Chinese device maker Lenovo unveiled the first consumer smartphone infused with Google's Tango technology. The $500 phone, called the Phab 2 Pro, will have a 6.4-inch screen and be available by September. (The phone itself is hulking, and Jeff Meredith, the head of Lenovo's mobile business group, said devices with both smaller and bigger screens are coming.)"

With Tango, Google is now equipped to map the entire world -- inside and out - CNET