Ask A Cartographer

Creating 3D Population Density Map

September 25 2008 | 3 comments
Categories: 3D Mapping, ArcGIS Methods

I found a this great 3D population density map created by Time Magazine:

I have been trying to recreate this map look, but have had little luck.

Here are the steps I have been taking:
1. Using Transportation Analysis Zones with population data, I created the centroids of each zone.
2. Using Spatial Analyst, I used the kernal density tool to show population density of the centroids.
3. I overlayed the centroids on a TIN in ArcScene and extruded by the New raster created by the kernal density tool.

- Now I have "peaks" similar to the Time Magazine map, but it looks more like mountains then the clean spikes in their map.

Do I need to do some type of post processing or is there a better way of trying to recreate such a map?


Mapping Center Answer:

On your first step, it looks to me like they just used City Points and then threw them into one of the Spatial Analyst's interpolations tools; I'd start with IDW.  That will give you a surface that you'll need in ArcScene or ArcGlobe.  It will be symbolized and used as it's own base heights. 

The only extrusion in this map is about a 5 mile extrusion on the states, and the states were also drawn on top as well. 

A quick test in ArcScene showed me that I could use US States extruded to a height of 20,000 meters.  Then I displayed states as another layer, but this time I set the base height to 20,500 meters.  Then I would set the base height of the population surface to 20250, and on the Base Heights tab, it will obtain it's elevation from a layer (itself).  You may have to adjust the population numbers (like add 20250 or normalize them if they're spiking too high).

I'll play around with this tonight and see what I come up with in terms of a more detailed set of steps and if I'm on track I'll put it up on the Mapping Center blog as I've had a few people ask about making this sort of map lately, so it will be a good thing to publicize.  Thanks!

Alternative to IDW posted by Charlie Frye on Sep 26 2008 1:35PM
While IDW can be tuned to work well for this sort of thing, I found it was easier to just use the Point to Raster tool and fuss with the cellsize to optimize the appearance in ArcScene.
Instructions posted by Katy Rich on Feb 27 2009 2:58PM
Have you been able to put together a more detailed set of instructions for making this map?

Katy Rich
Blog entry about the map posted by Aileen Buckley on Feb 27 2009 5:36PM
Have you seen this blog entry? It relates to procedures used to create a similar map.

If you would like to post a comment, please login.

Contact Us | Legal | Privacy |