Get city & country for latitude and longitude | The Coffeehouse

BeSharp

Can anybody recommend either a Web Service or an offline database solution which would allow me to get the city and country for any given latitude and longitude?

(Free solutions/services preferred but possible commercial solutions are welcome, too!)

-Ralf

ZippyV
Fired Up

http://channel9.msdn.com/forums/TechOff/258037-Databases-Storing-locations-and-finding-nearby-locations/

BeSharp

In reply to ZippyV

#Sep 7th, 2008 @ 5:30 AM

Thanks ZippyV,

I did the search on C9 myself, however, that discussion thread does unfortunately NOT answer the question I've posted here.

I'll repeat for the sake of being clear:

I know many services (Yahoo Maps API, etc.) that allow you to get Latitude and Longitude information when you send an address as the input. I do need it the other way around.

All I want to send as INPUT parameter ist Latitude and Longitude and as a return result I'd need city and country.

Any hints?

ZippyV
Fired Up

In reply to BeSharp

#Sep 7th, 2008 @ 5:53 AM

With that topic I did find a list but it didn't end up on Channel 9.

But I found it back:
http://earth-info.nga.mil/gns/html/namefiles.htm

BeSharp

In reply to ZippyV

#Sep 7th, 2008 @ 5:56 AM

Wow! With the data files made available there I might be able to set up my own web service to convert stuff! Great hint! Thanks!

ZippyV
Fired Up

In reply to BeSharp

#Sep 7th, 2008 @ 6:08 AM

Don't be too euphoric, the lists are not clean and contain other things like mountains, rivers, lakes. It's almost impossible to get a clean list of only cities and villages based on filtering the other columns.

BeSharp

In reply to ZippyV

#Sep 7th, 2008 @ 6:21 AM

Well, I only need to get a city from lat and long. I really wonder that none of the map providers (Google, Yahoo, MS) seem to have a web service for that. All of them offer you to input an address and get lat/long back but not vice versa...

figuerres
???

In reply to BeSharp

#Sep 7th, 2008 @ 6:25 AM

one interesting thing:

http://maps.google.com/maps?ll=27.950739,-82.459259 will give you a map of tampa, fl

when dealing with locations your database would need to have it updated often as names and countries do chnage.

another issue is how you determine the "city" from LL
LL math to find the distance between two locations can get a bit complex, as I recall it's called the Great Circle formla as it takes the cuve of the earth into account.

given a point and a distance you may get multiple location names, if several have non-zero distance and are very close which one do you pick?

andokai

That activity is called reverse geocoding . Do a google search and you can find loads of free choices. It is possible to do it with the map point web service as demonstrated here

http://virtualearth.spaces.live.com/blog/cns!2BBC66E99FDCDB98!536.entry?wa=wsignin1.0

Mark Brown
Microsoft Web Platform

Yes, Virtual Earth provides a reverse geocoding service in the platform API.

You can see this in our Interactive SDK, http://dev.live.com/virtualearth/sdk expand "Find Information (Basic)", then click on "Reverse Find"

MSDN Library for this, http://msdn.microsoft.com/en-us/library/cc469978.aspx

You'll have the parse the output if you just want city/state but that's pretty trivial.

Enjoy.

Niner

If you just want the list, Check the World Wide Telescope. It has the long list of cities with lat & long which again might be based on Virtual Earth only.