Wednesday 26 March 2008

Making maps with Google Chart API

A new version of Google Chart API was released last week. The most important change was the removal of the limit on the number of daily requests. I also noticed that a thematic map feature was added, and this is the result after some tweaking hours:

The map above shows the number of Internet user in the world (proportional). Only unclassified choropleth maps are so far supported by the API. Right-click on the image and select Properties to see the URL generating the map image. The URL contains country codes and values for most of the world countries, but the length (1308 characters) is still within the 2083 limit.

You'll find a quick tutorial for making maps with Google Chart API on this page. So far, I find the mapping feature of Google Chart API more suitable for "country highlighting" than for thematic mapping. The maximum size for maps (440 by 220 pixels) is too restrictive, as a world map needs more detail. I also miss a map legend, so the map reader can spot which colours represent high/low values. Still, it's a good start, and a greater advantage of Google Chart API is the possibility to put charts on top of maps.

UPDATE 6 APRIL 2008: A brief tutorial of thematic mapping with Google Charts API

Data source for Internet users: UNdata


riccardo zilli said...

i guess your elaboration was really good, and the issue of your work as well. have you an introduction-paper that can help me to understand better the thematic maps issue?
i hope to discover more about thematic mapping.
this could be a thematic maps?

sorry for my english! :)

Bjørn Sandvik said...

I recommend the book Thematic Cartography and Geographic Visualization. You can also have a look at this website.

Jeffrey Barke has made a brief tutorial about Thematic Mapping with the Google Charts API.

Hope this helps!

Anonymous said...

I just put up a map generator that uses the Google Charts API. It makes it a little easier to highlight the countries.

have a look

Anonymous said...

The only problem is that the size of 440 by 220 pixels is the maximum available for all maps. This is very small view...

Anonymous said...

I wish it had more parameters!!!

Anonymous said...

A great tutorial on creating heat maps with the new Chart API is here: