This dissertation aimed at determining whether Keyhole Markup Language (KML) could be used for thematic mapping. As a proof-of-concept, a fully functioning open source application, the Thematic Mapping Engine, was developed.

The use of geobrowsers has increased considerably over the last few years. Thematic mapping has a long history in cartography, but the new geobrowsers (like Google Maps and Earth) tend not to focus on this aspect of geographical information representation.

Even though KML is not targeted towards thematic mapping, it is possible to use KML elements in ways that were probably not intended. Current possibilities for making proportional symbol maps, chart maps, choropleth maps and animated maps with KML were examined.

These experiments show that KML and geobrowsers offer great potential for thematic mapping, but that there are significant issues that need to be resolved.

AIDS estimated deaths (aged 0-49) in southern Africa in 2005, represented as proportional image icons on top of Google Earth satellite imagery. Statistics from UNdata.

Mobile phone subscribers in South East Asia in 2004, visualised using a 3-D Collada object. The volume of the object is proportional to the statistical value (UNdata).

Example of how the Google Chart API can be utilised by the KML Icon element. The charts are scaled according to total population and the pie shows the age distribution for each country. Statistics from UNdata.

GDP per capital in European countries in 2006, represented as 3-D bars. Statistics from UNdata.

Unclassed choropleth map showing the infant mortality rate in Africa. Statistics from UNdata.

Infant mortality rate visualised as a 3-D prism map. Statistics from UNdata.

This image of Earth's city lights (NASA) was loaded as raster map tiles into Google Earth. The 3-D bars show CO2 emissions from each country (UNdata).