How to convert an address to a latitude/longitude?

Question

How would I go about converting an address or city to a latitude/longitude? Are there commercial outfits I can "rent" this service from? This would be used in a commercial desktop application on a Windows PC with fulltime internet access.

Answer 1

Google has a geocoding API which seems to work pretty well for most of the locations that they have Google Maps data for.

http://googlemapsapi.blogspot.com/2006/06/geocoding-at-last.html

They provide online geocoding (via JavaScript):

http://code.google.com/apis/maps/documentation/services.html#Geocoding

Or backend geocoding (via an HTTP request):

http://code.google.com/apis/maps/documentation/services.html#Geocoding_Direct

The data is usually the same used by Google Maps itself. (note that there are some exceptions to this, such as the UK or Israel, where the data is from a different source and of slightly reduced quality)

Answer 2

You want a geocoding application. These are available either online or as an application backend.

• Online applications:

  • Google has a geocoding API

• Backend applications:

  • GeoStan

Answer 3

Maptsraction (http://www.mapstraction.com) lets you choose between any number of geocoding services. This could be helpful if you need to do large quantities, as I know Google has a limit to how many you can do a day.

Answer 4

Virtual Earth does it. There is also a web service at geocoder.us

Answer 5

When you convert an address or object to a lat/long it is called Geocoding.

There are a lot geocoding solutions around. The solution right for your project will depend on the acceptability of the licensing terms of each geocoding solution. Both Microsoft Virtual Earth and Google Maps offer solutions which are free to use under a very restrictive licenses...

http://code.google.com/apis/maps/documentation/services.html

http://www.microsoft.com/virtualearth/product/faq.aspx

Answer 6

Yahoo! Maps Web Services - Geocoding API

Answer 7

Yahoo! Maps Web Services - Geocoding API accurately geocodes UK postcodes, unlike Google's API.

Answer 8

Having rolled my own solution for this before, I can whole heartedly recommend the Geo::Coder::US Perl module for this. Just download all the census data and use the included importer to create the Berkeley DB for your country and point the Perl script at it. Use the module's built in address parsing, and there you have it: An offline geocoding system!

Answer 9

Nothing much new to add, but I have had a lot of real-world experience in GIS and geocoding from a previous job. Here is what I remember:

If it is a "every once in a while" need in your application, I would definitely recommend the Google or Yahoo Geocoding APIs, but be careful to read their licensing terms.

I know that the Google Maps API in general is easy to license for even commercial web pages, but can't be used in a pay-to-access situation. In other words you can use it to advertise or provide a service that drives ad revenue, but you can't charge people to acess your site or even put it behind a password system.

Despite these restrictions, they are both excellent choices because they frequently update their street databases. Most of the free backend tools and libraries use Census and TIGER road data that is updated infrequently, so you are less likely to successfully geocode addresses in rapidly growing areas or new subdivisions.

Most of the services also restrict the number of geocoding queries you can make per day, so it's OK to look up addresses of, say, new customers who get added to your database, but if you run a batch job that feeds thousands of addresses from your database into the geocoder, you're going to get shutoff.

I don't think this one has been mentioned yet, but ESRI has ArcWeb web services that include geocoding, although they aren't very cheap. Last time I used them it cost around 1.5cents per lookup, but you had to prepay a certain amount to get started. Again the major advantage is that the road data they use is kept up to date in a timely manner and you can use the data in commercial situations that Google doesn't allow. The ArcWeb service will also serve up high-resolution satellite and aerial photos a la Google Maps, again priced per request.

If you want to roll your own or have access to much more accurate data, you can purchase subscriptions to GIS data from companies like TeleAtlas, but that ain't cheap. You can buy only a state or county worth of data if your needs are extremely local. There are several tiers of data - GIS features only, GIS plus detailed streets, all that plus geocode data, all of that plus traffic flow/direction/speed limits for routing. Of course, the price goes up as you go up the tiers.

Finally, the Wikipedia article on Geocoding has some good information on the algorithms and techniques. Even if you aren't doing it in your own code, it's useful to know what kind of errors and accuracy you can expect from various kinds of data sources.

Answer 10

You could also try the OpenStreetMap NameFinder (or the current Nominatim), which contains open source, wiki-like street data for (potentially) the entire world.

Answer 11

The USC WebGIS Geocoder is free and offers several API's, or you can upload a database for online batch processing.

Answer 12

You can use Microsoft's MapPoint Web Services.

I created a blog entry on how to convert an address to a GeoCode (lat/long).

Answer 13

Check out the geocoding app - bulkgeocoder.com. It allows the user to upload a file with the records directly exported from a DB table ( with address, city and/or zip), Processes it and then allow the user to download the updated file. This could be used to bulk geocode an entire database.

Answer 14

you can use bing maps soap services, where you can reference reverse geocode service to find lat/long from address here is the link http://msdn.microsoft.com/en-us/library/cc980922.aspx