Christopher Fiock came to a rest. For more than four hours he and a team had mapped the Presidio of San Francisco, the former army post that is now a national park. With every step they took, the team captured panoramas that would soon let the world explore the Presidio without leaving their computers. At a vista overlooking the South Bay, Fiock demonstrated the device that had made it all possible: the Trekker, the powerful if awkward device that recently concluded its first year as one of the technological engines of Google’s six-year-old Street View program. "The Trekker is a mobile image-capture platform," Fiock says. "We took some of the same technology from the Street View cam and made it portable — ultra portable."

This week, panoramic imagery from the Presidio went live on Google Maps for all to see. It’s part of a suite of new national parks coming to Street View that also include Joshua Tree, Yellowstone, and Sequoia. For the past year, the Trekker has journeyed to ever more improbable locations, from the bottom of the Grand Canyon to the top of Mount Fuji. In recent months the device visited Venice, Italy; the Galapagos Islands; and dozens of national parks in the United States and Canada. While Google Search crawls the web, "we crawl the physical world, taking pictures," says Luc Vincent, engineering director on the project. "And try to make sense of them, try to make them useful."

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Along the way, Street View has come to serve an important strategic purpose. In the wake of Google Maps’ removal as Apple’s default mapping system in 2012, Street View has offered iPhone users regular and impressive glimpses at what they’re missing with Apple Maps. "To me it’s magic," says Steve Silverman, who helps build the Trekker hardware. "You can pull a smartphone out of your pocket, see your friend’s house, and know which door to knock on. That’s why we do this."

At the same time, Street View has frequently and famously been a source of controversy for the company. Street View has a dedicated and lengthy Wikipedia page devoted to documenting privacy issues surrounding its imagery, from hundreds of thousands of Germans opting out of having their homes included to US officials demanding that Google remove images of military bases.

Apple Maps has proved a surprisingly strong competitor

And when Apple introduced its own take on maps, Google Maps gained a competitor that proved surprisingly powerful once it got past its initial disastrous reception. Google Maps lost nearly 23 million users in the United States after the switch, the Guardian reported this month, citing numbers from ComScore. Apple Maps is now used by 35 million people a month, according to ComScore, compared with 58.7 million people who use Google Maps across iOS and Android.

Google won’t share user numbers of its own. But the rise of Apple Maps underscores the strategic importance of Street View: the more places that Trekker visits, the more Google Maps keeps its competitors playing catch-up.

The streets of Palo Alto

The earliest idea for Street View came from the top. In 2003 Google co-founder Larry Page cruised the streets of Palo Alto with a camcorder recording footage, and gave the video to a professor he knew at Stanford, suggesting he investigate new ways of mapping. This took place before Google’s October 2004 acquisition of Keyhole, the product that would transform into Google Maps. Eventually a small group of Googlers began working on the Stanford research project in their so-called 20 percent time, in which employees spend a portion of their week working outside their main area of focus.

Among that group was Vincent, who joined the company in early 2004 to work on Google Books. Vincent had a background in optical character recognition and document imaging, but he became excited about the prospect of building a new map. Google granted the group a handful of summer interns, and together the team worked on what would become Street View.

The first Street View vehicle was a nondescript van

The first vehicle used by the team was a nondescript van. Video cameras extending from the vans’ sides captured images at a high frame rate, in keeping with the original idea for Street View as a video map of the world. But the team kept running into technical problems with the videos. To hedge their bets, they decided to equip the van with an additional "rosette" of eight cameras, which would capture their surroundings in 360-degree panoramas.

The panoramas proved much more reliable, and the team used them to map the first five cities in the program. On May 29, 2007, Street View launched as a new part of Google Maps in San Francisco, Las Vegas, Denver, Miami, and New York. As the program grew, the van was replaced by the now-familiar Street View car, and the less familiar tricycle, trolley, and snowmobile. The program is now available in more than 3,000 cities across 54 countries, covering more than 6 million unique miles of road.

20 percent time

Like Street View itself, the Trekker began as a 20 percent project. Many trails and pathways aren’t accessible via car, and negotiating the trolley up flights of stairs proved all but impossible. About three years ago, an engineer working on the Street View hardware team began to play with the idea of a camera housed in a backpack.

To make it work, the team had to reimagine a device built for a car so that it made sense on a person. "People are generally not able to run at 60 mph," Silverman quips — which proved helpful to the team, since they were able to record images at a lower frame rate than the car cameras. At the same time, they had to take a navigation system that was the size of a laptop and compress it down to a single circuit card. And they had to manage the device’s power so that it could run on lithium ion batteries instead of a car engine. At one point a group of Googlers in Mountain View saw Silverman, in swim trunks and with a Trekker strapped to his back, hopping into a lap pool just to make sure the thing floated. "We have a suspicion that at some point it will go swimming unintentionally," he says.

Trekker weighs 42.5 pounds

The resulting Trekker is still relatively heavy at 42.5 pounds. A long neck extends from the backpack to the orb-like camera array, which comprises 15 cameras that capture images at a combined 75 megapixels. Trekker’s batteries last between six and seven hours, and fills its hard drive with 256 GB of data. And yes, Trekker floats — it’s watertight to 60 feet.

In the Presidio, Fiock and his crew operate the Trekker using an Android smartphone that attaches to the device via USB. The operator simply hits record on a custom app and the cameras start snapping. "If you can see Trekker, Trekker can see you," Fiock says. Once the images are uploaded to Google’s servers, the company’s algorithms stitch the images together into panoramas. They also blur out any faces or license plates for privacy reasons. In as little as a couple of weeks, the images can be ready to post online.

The flying backpack

So what’s next for Street View? The feature is not without direct competition; Bing Maps introduced the similar Streetside view in 2009. And while Apple has yet to incorporate ground-level imagery into its Maps app, the company’s recent acquisitions of mapmakers suggests it will eventually do something in that vein.

Street View set our expectations of what a map should look like

If that happens, it will be partly because Street View helped to set our expectations of what a map should look like — and that no matter where we wanted to look, we could simply drop a peg on a road or trail and immediately feel like we were there.

In the meantime, Google is pushing forward on its new plans. A new version of Trekker is now under development, with the goal of reducing its weight and power consumption by a factor of two. And it’s wading through a backlog of organizations that have requested to borrow the Trekker to map their own spaces.

Silverman, who in a previous job launched sensors that flew to Mars, is still thinking big. Once in Brazil a woman approached the Trekker team and asked if the backpack could fly. Silverman laughs, recounting the story. "We had to say — not yet."