Posts Tagged ‘precision’

Being the Fastest Is Not Enough (InfoGraphicsNews)

Wednesday, August 19th, 2009

mapita22

[Editor's note: You'll start seeing more mashups on The Washington Post site the next month. Staff are being trained to use a new mashup maker tool I made that churns out decent maps in 5 minutes flat. Just like in print, normal rules about accuracy in reporting apply. The bottom line, don't show more location detail than you know to be true, as this blog post from InfoGraphicsNews illustrates. Thanks Laris!]

Republished from the InfoGraphicsNews blog.
Original on 12/04/2008.

Yesterday, the terrosrist group ETA killed another person in Spain. In this cases, as most of the cases, internet media have the initative. The first idea is to place the new. Shw where it took place. But the problem is that in this kind of news all the information is changing all the time during the first hour, and the data are not accurate. Yesterday, we only knew that Ignacio Uria was killed while he was going to his favourite restaurant, Kiruri. We didn’t even knew if he came form his house or form his job.

The punch line:

None of those that placed the killing on a exact place were right.

Some rectified later, others didn’t even change it. Being the fastest can’t go before telling the truth. On reconstructions many editors use to say that “the reader know this is not exactly the truth, that we’re just guessing”. I don’t want the reader to not trust us. I prefer to have a reader who really think that when we say something we know it and we’re not guessing.
These are screenshots from some spanish websites two hours after the agencies gave the news:

Continue to view screenshots at InfoGraphicsNews blog . . .

Privacy and GeoTagging Photos with GPS-enabled iPhone

Tuesday, July 29th, 2008

flickr geotag example map

Being able to record where a photo is taken one of the key features of the new iPhone. Not only does the phone capture a great picture but there is no residual “Now where was I”. You can instantly see where the photo was taken on a detailed map. This is great for geocoding when surveying, but what are the social implications?

Do you want to share this level of detailed personal information?

Why wouldn’t you? Consider this:

Upload a week’s worth of photos.

  • One taken on the way into work of that cute gal you always see at your metro station
  • Another in your office for a coworker’s going away party
  • Another taken at your favorite dance club
  • Another taken at the great brunch place you go to on Saturdays and
  • Another of the pile of laundry you’ve been ignoring all week

Normally you are adding captions and keywords that someone who already knows you can piece together and perhaps guess or already knows where all these physical places are. But you’ve gate-keeped based on “you need to know me and know enough about me” to get it.

Up until now, you’ve controlled the information flow based on how much you tag the photo in the context of how well your online “friends” know you.

Related links: adding GPS locations to photos when you don’t have a GPS (one) (two) (three) (four) (five).

GPS tagged photos are game changing

Now someone who doesn’t know anything about you, and with whom you might NOT want to share that level of personal information, can instantly become your first stalker. They know exactly where you live, exactly where you work, exactly how you get to work, and exactly where you relax and have let down your guard.

Something to consider as an adult and perhaps lock-down if your child has a GPS-enabled cell phone.

Of course, if you’re on a tourist trip and taking pictures of Yellowstone and the Statue of Liberty and are never going to be there again it’s perfectly fine to include the full GPS coordinates since that doesn’t disclose personal information and you’ll not routinely passing by there again. However, if you visit Aunt Mildred in Brooklyn on the same trip you might want to limit access to her home’s location.

I’m invincible, right? What do I care?

Consider the following two situations:

  • I was at a friend’s house party on Friday and took a few pictures and was about to post them when it hit me: I’m potentially compromising her safety, not just my own. If I post those GPS enabled photos some random person could view the photo (hey, it’s up on Flickr for anyone to browse) and know which front door to be waiting at. Skechadellic, dude!
  • I have a swimming hole I’d like to keep on the down-low but when I go out there I take a few shots with my camera to remember the scene. If I post those on Flickr with the GPS coordinates suddenly anyone that views my the photo tagged “My secret swimming hole” can see it placed exactly on that blue map polygon and route directly to it. Not so secret after all. Oops!

So it turns out Flickr has a way to moderate this to an extent. There is a setting to control this, sort of. Screenshot below:

flickr geotags

Notice how I do NOT have this option checked. But my GPS information is still being read in and placed on my account map somehow. Bad!

User Solution 1

The best, fail-proof option is to not record the GPS information when the photo was taken. But then you loose that information for your personal record. The iPhone asks the first time a GPS enabled application is launched if you want to allow it access to the GPS. Press “Don’t Allow” and you’re set.

But once you have enabled the camera to know the location you can’t disable it until the phone is turned completely off and restarted, less than convenient and oh so easy to forget about. You can go to the General Settings area of the phone and turn Location Service on and off without restarting the phone, however.

iphone use current location

User Solution 2

There should be a middle way when uploading and displaying on photo sharing sites like Flickr. This way you retrain full GPS location for your private records but only let out an approximate public location for everyone else.

For the Mac you can download PhotoInfoEditor to edit the precision of the GPS coordinates stored in the EXIF information for the photo (or a duplicate targeted for public upload). I had a devil of a time finding this app as most simply report the GPS coordinates; they do not allow them to be edited. If someone knows of a comparable app on the PC please email me.

Notice in the screenshot below that I have stripped the latitude and longitude to display to the hundredth (39.35° N). You could just as well scramble the coordinates down to the 4th or 5th decimal position when in the city and still be in the right neighborhood but no longer be at the right building. Photosets can be batched adjusted.

This puts the photo in the rough vicinity of the actual location but does not reveal the actual location

. photo info editor screenshot

When you do this before uploading to Flickr or Picasa you can have the benefit of placing your photos on a map with some accuracy but just not with a high precision. In other words, don’t zoom too far into the map or the photo locations become inaccurate. But zoomed out they are perfectly acceptable.

How can software be improved?

On upload / display of the photos in a social photo site:

  • Group permissions for viewing Placename tags and GPS coordinates on map with default being NOT to show the geographic location but to apply limits of precision with individual photo exceptions as detailed next:
  • On / off toggle for Placename tags per photo
  • On / off toggle for GPS coordinates per photo
  • Placename precision (country, state, county, town, neighborhood) from Yahoo or Google geocoder as a slider control per photo
  • GPS precision (exact, 1/4 mile, 1/2 mile, 1 mile, 2 mile, 5 miles, 10 miles, 20 miles, 60 miles) for latitude and longitude as a slider per photo

The GPS precision needs to take into consideration that the number of earth miles at each degree of latitude changes. Simply chopping of decimal places is a crude solution. A more elegant solution would be to add a random ± X decimal degrees to the actual location at the target precision. Even though the iPhone GPS can get you down to 10 meter accuracy, sometimes you don’t want to be that precise.

I’ve already spoken to the developer at AirMe which is my favorite app on the iPhone for uploading to Flickr and he seems interested in making the required upgrades to his application. Please help spread the word to other developers!

It’s Still a Big City, Just Not Quite So Big (NY Times)

Wednesday, May 28th, 2008

[Editor's note: When asked to report the length of a border frontier I often pause a moment to reflect on map scale and precision. Both are developed in this article by Sam Roberts on how New York City has just shrunk by 5% in area due to a few cartographic slights of hand.]

over estimating new york city

By SAM ROBERTS. Published: May 22, 2008. Thanks Denny.

Graphic one (above) and 2nd graphic accompany the article.

Somehow, Michael S. Miller resisted the temptation when he got home not long ago.“Honey,” he would have been completely justified in proclaiming to his wife, “I shrank the city.”

Mr. Miller, a geographer for the Department of City Planning, has calculated that New York City is 17 square miles smaller than it was long thought to be.

For two decades, the city’s official directory, the Green Book, has stated definitively that the five boroughs encompass nearly 322 square miles of land.

Not so, Mr. Miller and his staff recently discovered: New York’s land area actually totals 304.8 square miles.

The shrinkage generally is not the result of rising sea levels from global warming or beach erosion or any other act of nature. It is largely the work of man, mainly Mayor Michael R. Bloomberg, whose yen to precisely measure everything from poverty to traffic congestion led the planning department to recalculate the city’s land mass.

Acting on the mayor’s mandate, Mr. Miller and his team spent months analyzing thousands of digitized, high-resolution aerial photographs of the squiggling shoreline and other geographic features to calculate the city’s size anew.“

This is not a reflection of a change in the physical area, but a refinement of the measurement,” Mr. Miller said.Seventeen square miles may not seem like much. But consider:

¶17 square miles could accommodate 13 more Central Parks, nearly a third of Washington, D.C., about three dozen versions of Vatican City and nearly two dozen replicas of Monaco.

¶If 17 square miles were populated at Manhattan’s density, New York might be home to as many as 1.1 million more people.

¶At the price of an acre in Midtown, as recently computed by the Federal Reserve Bank of New York, 17 square miles could be worth $1 trillion.

Mr. Miller said the recalculation probably would have little practical effect, other than revising the land area chart in the 2008 Green Book and amending other official records, textbooks and statistical abstracts. Its psychological impact might be significant, however, coming as it does at a time of political and economic uncertainty. With Wall Street firms shrinking, how will people respond to the news that Brooklyn is, too?

“All everybody else can talk about is how much bigger China and India are getting,” said Sylvie Smoke, 59, a retiree from the Upper West Side. “And we are losing it.”

On the other hand, given the effect of the credit crisis on real estate prices, some property owners might be pleased. If there is less land, maybe it will be worth more.

“I guess,” said Mike Slattery, senior vice president for research of the Real Estate Board of New York, “it’s good news for those who still have it.”

Planning department officials stress that their new measurement is only an estimate, an approximation subject to the vagaries of time. Over the course of four centuries, they note, the city’s land area has actually grown because adjacent waterways were reclaimed for development in Lower Manhattan and in Queens to extend the runways at Kennedy International and La Guardia Airports.

The new estimate, which will appear in the 2008 Green Book, to be released next month, reduces New York’s official size by about 5 percent.

But even in its supposedly diminished form, New York still ranks 14th in land area among cities with more than 100,000 people, according to the United States Census Bureau. (Anchorage covers nearly 1,700 square miles; Jacksonville, Fla., 758.) The new calculation also conforms more closely to census estimates.

Mr. Miller, 52, the planning department’s deputy director of information technology, said the apparent loss in land mass was distributed throughout the city.

“There’s no neighborhood that’s vanished,” he said.

That said, about seven square miles of the difference could be accounted for by better measurements of the islands and peninsulas in Jamaica Bay. And it appears that Brooklyn shrank the most, by about 12 percent, to 72 square miles from 82.

Continue reading . . .