background preloader

CHOROPLETH MAPS

Facebook Twitter

Technisches Werken. Creating Contour Maps. Creating Contour MapsCreating 3d contour maps using heightmaps in processing. For some of our past projects we were in the need of creating 3d contour maps in Processing. A contour, or topographic map, uses contour lines which join points of equal elevation above a given level to show valleys and hills.

You can think of these lines as intersection of a 3-dimensional surface and several horizontal planes. The following tutorial will cover two main questions. How to generate these contour maps in processing. And how to get the greyscale heightmaps that are needed for the map creation. Creating a contour map We started working on different approaches creating the contour maps but realized most of them were either too slow, the results were not really satisfying, or it wasn’t possible to transform them to 3d as they were pixel based. So after testing different libraries, we decided to use v3gas Blob Detection library which seemed to be the best for our purpose. Processing code PImage img; Home.

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: Naturally, I wanted to know where the differences come from and spent some time to investigate. Don’t mess around with your class limits The values in the poverty data range from 6.6% to 22.7% and the map shows them divided into five classes.

I’m not sure if this is the default behaviour of Google Fusion Tables or the editors choice, but the Guardian map used the class limits 6-9%, 9-12%, 12-15%, 15-18% and 18-23%. Don’t mess around with your class colors Quite a different picture, isn’t it? How to Make Choropleth Maps in D3. Even if you think you don’t know what a choropleth map is, chances are you’ve seen one. And come November 2012, you’ll see plenty: one iconic example of a choropleth map is a map of the United States, laid out in red and blue, showing the results of a presidential election. Choropleth maps can be simple, like in the example above, where the color of the state indicates whether the state goes in one direction (Democrat) or the other (Republican).

The states can also be colored on a scale to indicate data, with a color like blue representing a low number and red representing a high number, leaving a number in between to be purple. These simple visualizations make large amounts of data easy to understand at a glance, allowing insights that would take much longer if you’re looking at a table of numbers.

There have been tutorials for Python and Excel, but none that we’ve seen yet for D3 — and D3 is one of the easiest ways to make choropleth maps for the web. Let’s start with our base map.