Open up Google Maps on your phone and, depending on where you are, you'll see some streets, some buildings and a blue dot. That blue dot is you, in "YOU ARE HERE" form. When you move, it moves. The dot is helpful when you're walking around outside, but if you're indoors -- in an airport, a mall, or even a conference venue, like I am today -- you might as well be in no-man's land.

Google wants to change that with something called Tango.

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.)

But back to the maps -- and that blue dot.

When you're indoors, "all it tells you is, 'You're in the airport!' Which is not super helpful," Johnny Lee, head of Tango, said in an interview Thursday at the Masonic, the San Francisco venue where Google and Lenovo unveiled the Tango phone. It doesn't come in handy when you want to tell someone to meet you at Baggage Claim 4.

"It's about making a better blue dot," he said.

James Martin/CNET

For Google, the stakes are huge: If Tango takes off, the company has the potential to have the most complete picture of the physical world -- both outdoors and indoors -- that anyone has ever had. It already owns a satellite company called Skybox that can take detailed pictures of Earth from space.

"Being able to search the physical world, kind of like you'd search the web, is really interesting," said Lee. "One day, it's something we could hopefully do."

Now playing: Watch this: Project Tango makes augmented tech a reality

With a Tango phone, you'd be able to peer inside buildings. The technology lets you map out a room, with the phone's sensors and four cameras capturing all of the parameters and measurements of the room itself and everything inside it.

The idea is that venue owners would use Tango's technology to map out their building's interiors and release that data to Google so people with Tango phones could use that information when they're in the building. Lee won't reveal how many venue partners Google already has, but says he hopes there will be a "few" live later this year. One partner is the home improvement chain Lowe's. Lee says Google has also done a pilot test with the San Jose International airport. (Google has another project for mapping the interiors of buildings using a special laser-scanning backpack called the Cartographer, but Lee says that's a separate project.)

As with any Google service, there are privacy implications. Lee said you can think of Tango-related data as you'd think of YouTube videos. When you shoot a video on your phone, you can keep it on the device or you can upload it to YouTube and share it widely. With Tango, when you map a room, it creates a computer file with the exact specifications of that room, and the file stays on the device. Or you can share it, as Google hopes venue owners will do.

Dinosaurs and sofas

Lenovo has a roundabout history with Google. The Chinese company owns Motorola Mobility, which it bought from Google in 2014. Google originally bought Motorola for $12.5 billion in 2012, before selling it off to the Chinese phone maker two years later for $3 billion. Google didn't come away empty-handed though; it kept a cache of important patents. It also retained Motorola's experimental hardware division, called Advanced Technology and Projects, or ATAP. That division created Project Tango.

The technology isn't only for traditional maps. Google wants you to use it for everything from shopping to education to gaming. (Tango is actually a part of Google's virtual reality division.) On Thursday, the company showed off a handful of demo apps, including one for creating elaborate, digital dominoes setups, and one from the American Museum of Natural History, which will show you a digital image of a Tyrannosaurus Rex on your phone, at scale if the room you're in is big enough. The common thread among all these experiences is that Tango has all that information about the size of the room. Because of that, it can show you 3D images on your phone's screen as if they were there in real life, something in tech-speak called "augmented reality."

Shopping could be one of the most lucrative uses for Tango. One of the biggest boons of the technology is helping to guide consumers around stores, said Richard Maltsbarger, chief development officer at Lowe's. The retailer has an app that will help you pick out furniture and see if it will fit in your house.

"We have 200 million square feet of retail," Maltsbarger said. "So we're looking for the day where we actually know where every item is in that 200 million square feet." That's for both customers and employees, he says.

Lee adds that, in the future, Tango could lead people "to a store, to an aisle, to a shelf, to a product."

Google may already be laying the groundwork for cashing in on Tango. Last month, it announced a new advertising unit called promoted pins, which would let retailers highlight specific product deals at nearby stores when consumers are using Google Maps. At the time, Sridar Ramaswamy, Google's senior vice president of ads and commerce, said it was too early to talk about linking Tango to Maps advertisements. On Thursday, Lee said, "there's nothing we can commit to right now" with Google Maps.

But the possibility is there. And that blue dot might as well be an X on a treasure map.