Take Care of your Choropleth Maps

Over the last week I had some fun playing with choropleth maps. Thereby I analyzed the following US poverty map, which was recently published at the Guardian data blog:

To be honest, the first time I saw this map I didn’t thought much about it. Ok, poverty is highest in south central of the United States, especially near Mexican border. But recently I used the same data to demonstrate a choropleth map that I created from-scratch and I was really surprised to see a somewhat different picture:

click to dig into the world of choropleth maps..

Simple Map Visualization In Flash – German Population Density

Today I’m going to demonstrate a simple geospation visualization in flash. Therefore I used a scalable vector graphic of germany which contains individual shapes for every district. and labeled them to the specific district id used by lots of datasets. The common source for data about germany is the german department for statistics. This time, I just used the population density which is the number of people living in a district divided to the districts area [km²].

The svg and the dataset are embedded into the flash movie for a better compression (800 -> 270kb)  and to enable the offline usage of the visualization. The svg is processed using a simple string based svg parser which just extracts the shape coordinates (either svg-polygons or svg-paths) and labels. I used the formerly introduced class PerceptualColor to map the data to hsl color values.

Update: added some interactivity and display for selected details.