শনিবার, ২৯ সেপ্টেম্বর, ২০১২

Why I never trust GPS maps completely (and you shouldn't either)

23 min.

On a trip to Oregon's?Willamette Valley in the spring of 2010, I was using the Google-powered?Maps app on an iPhone 3GS to hunt down wineries while my friend drove.?

That's farm country, and driving on dirt roads is pretty much expected. Nevertheless, it seemed odd when the app told us to turn onto a gated farm driveway.?

Then we saw the sign: "Sorry your GPS brought you here. To get to the winery you came for, turn around and go back?" It was polite, but you could sense that the farmer who posted it was somewhere on his tractor, smirking.

There's an old sailor's adage: Always carry at least two forms of navigation.

While that no longer means "pack a sextant," it does mean you should at least?have a back-up GPS app, a separate GPS device?or even a honest-to-gosh?dead-tree road atlas when you're in unknown territory.?Thanks to the well-publicized shortcomings of Apple's new Maps app???the first one that's?not powered by Google data???our blind reliance on GPS apps has become quite clear.

As a tech writer and navigationally challenged human who's reviewed GPS gadgetry for 10 years, I've learned that?any system can be as flawed as it is useful, and you should never trust it 100 percent.

Back in the early 2000s, before we were married, my wife lived for a couple of years in Washington, D.C. and I would head down there from New York on weekends.?When you're driving along in D.C., numbered roads veer into lettered roads, and?you have to make a lot of weird corrections?every few blocks, all the while risking driving straight into a fountain or a statue of a man on a horse. While D.C. residents take pride in the "National Treasure"-grade mysteries of getting around the nation's capital, outsiders like me fail to appreciate it. So when GPS became a thing, I was all over that.

My wife and I referred to the first GPS navigator as "the other woman," but in reality, this authoritative, British female voice was a relationship counselor: When road rage was high and we weren't listening to each other, we would both listen to her.

During that period, I tested a lot of GPS products for my weekly column on Time.com and for pieces in the New York Times and Money Magazine. I got to try out all of the major brands, and compare them side by side.?With GPS, even D.C. was, for the most part, much easier to get around in.?

But there was one map error that constantly perplexed us: When driving back from the Pentagon City Mall to Southeast D.C., we would always be told to take an exit that didn't exist. New construction, you may think, but there was no evidence that the exit ever existed. At least not where it told us it was.

The sudden surge of consumer GPS gadgets around 2001 and 2002 was caused by the U.S. government allowing civilian hardware to access the?1-meter GPS?accuracy that had previously only been available to military devices.?

But GPS only tells you where you are in latitude and longitude?? building?the visual maps that need to be placed under those pinpoints is a challenging multi-billion-dollar endeavor. Even Google???which stood on the shoulders of mapmakers such as TomTom-owned Tele Atlas and Nokia-owned Navteq when building its remarkable geographical database???can get it wrong every so often.

The world is constantly changing???roads and bridges spring up, while old ones are closed off. Cow pastures become shopping centers. Restaurants and bars open and go out of business. A broken clock may be right twice a day, but?a map of the world really never is.

In 2004 or 2005, TomTom was pitching me on its latest dash-mounted navigator. I had favored Garmin (which used Navteq's maps, which experience had suggested to me were more reliable than the Tele Atlas ones used by TomTom). Nevertheless, I was willing to give TomTom (and Tele Atlas) another try. When I set it up, however, I noticed a real problem: My home wasn't on the map.?

The best rationale was that my street was part of a new-ish apartment development, but excuses don't work when you can't even get home! The apartment complex in question has since been added to the Tele Atlas database???sure enough, it?appears on the new Tele Atlas-powered Apple Maps app.

But even my preferred Garmins gave me trouble. When I went to the wedding of one of my best friends, out in rural Vermont, the GPS system would get me within a mile of his house, but leave me out on a road in the middle of a field. Finding his house from there?required dead-reckoning, though the balloons on the mailbox didn't hurt.

Down in Texas, visiting my brother-in-law, even a simple search for Starbucks once turned into an existential nightmare (made worse by lack of caffeine). The "point of interest"???those geo-tagged yellow pages that are the least reliable part of the GPS map experience???plopped a Starbucks smack in the middle of a quiet residential street. We never did quite figure out where that phantom Starbucks really was, or if it existed at all.

Smartphones were thought to be the holy grail, because they could download fresher (and therefore???we naively assumed???more accurate) maps on the fly. Never again would a random construction project take you by surprise. So we cheered the arrival in 2009 of bona-fide turn-by-turn smartphone?navigation, particularly the free version that?Google offered on the Motorola Droid and subsequent phones running?Android 2.0.

For iPhone users, GPS navigation was a double-edged sword, because without Apple providing a free homegrown navigator,?people who wanted live turn-by-turn instructions had to pay up in the App Store, sometimes up to?$100. The bulk of iPhone owners stuck with the native Maps?app, powered by Google, and even though it was only at its best?when you had a navigator riding shotgun, who could read out instructions,?its accuracy became the gold standard.

Cue all hell breaking loose when Apple swapped it out with their own approach, powered by the Tele Atlas map?database instead of Google's. The problems there are compounded: It's not just that some of the map data is screwy, it's that the points of interest that are pegged to the map can be way off.?

To make it worse, Apple oversold the 3-D multitouch map?manipulation. While?it looks insanely great when fully operational, it looks downright screwy when rendered wrong or used in an unsupported area (like most of the world). Apple bit off more than it can chew and, as CEO Tim Cook's apology indicates, the company is choking.

The other day, my family was packed into the minivan, heading from Seattle to a friend's house across Lake Washington. Our car's navigator was trying to take us over the 520 toll bridge, but Apple's Maps app was saying to go over I-90, which is free. We steered in that direction, and were glad we did: Turns out, the 520 bridge was closed all weekend.

It's at this point that a sane person just throws up his hands. If the free Apple upgrade works some of the time, and my car navi works some of the time, and I've also got the Garmin app and?Google maps via the browser, the real answer is the sailor's law: Reliance on one navigation tool is stupid, so always have a back-up.

Wilson Rothman is the Technology & Science?editor at NBC News Digital. Catch up with him on Twitter at @wjrothman, and join our conversation on Facebook.

Source: http://www.nbcnews.com/technology/technolog/why-i-never-trust-gps-maps-completely-you-shouldnt-either-6143202

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