Geocoding with QGIS and Google Maps

Translating large numbers of unstructured addresses into exact geographic locations (coordinates) was my competitive edge: Write a little script in Perl that feeds the Google Maps API with (unstructured) addresses, retrieve and store Google’s replies – et voila: Let the GIS analysis begin.

Obviously, I could have asked commercial geocoding services to provide me the locations of my data points. There are some major drawbacks when using “professionals” that I do not like:

  • They are expensive. Actually, I admire them for charging feesĀ  for a service that can be accomplished with free tools in the market.
  • The results are like meatballs: You do not really know what ingredients went into it. Relying on Google maps at least allows a graphical sanity check.
  • They are slow. Imagine, you really really need this extra layer of information on a Friday afternoon to go on with your research… When doing it yourself, you can have the answer within minutes.

The good news is: No scripting is needed anymore to do free and fast geo-coding. The open source GIS software QGIS (it is free and runs on all operating systems!) now has a plugin that does all the interaction with Google’s web service. It is still a bit rudimentary, but, hey, it does its job.

Just check out Steven’s great article on how to get it running on your machine.

Author: thies

Lecturer (Assistant Professor) for Real Estate Finance, Cambridge