Friday, January 30, 2009

GeoCommons for Choropleth Map Creation

So I have a funding for an education project to integrate choropleth maps into teaching. The basic idea is to use new web tools to allow students to create polygons and then attach data to the polygons and allow the students to play around with the intervals and colors to learn how to present choropleth maps and learn more about the topic in hand. For example, I'm going to get some students to work together to create a map of tree density around Mt. St. Helens. For fun, you could see what patterns they will end up seeing, I've marked 2 areas for you to look at below. Your clue as to what is happening is that Mt. St. Helens was famous for erupting through its side (hole still visible) in the 1980s:

Open KMZ in Google Earth

So I have been looking at building choropleth functionality myself with the GMaps, or GEarth API but GeoCommons looks like it could fit the bill so its worth more of a close look than I gave it here.

Upload Formats: At the moment you can upload choropleth data in shape files and then manipulate them, I'm told that being able to upload KML polygons will be possible soon, they have a bug fix waiting for the next update. The point of wanting to be able to upload KML files is that I want students to be able to use and manipulate choropleth maps without having to get into GIS proper.

Screen shot of GeoCommons Maker

Usability of GeoCommons Maker: Overall the process of manipulating your choropleth map is really easy compared to the skills you would need to do it in GIS. Nice features are:
  • The ability to pull in different backgrounds including a blank screen
  • A set of standard color palettes,
  • clear and sensible option buttons top right
  • all the other positives I've pointed out before.
I have got some suggestions as to how to make Maker (what they call their map editing tool) easier for none GIS users (highest priority first):
  1. I don't like the options for sorting data classes, there are a lot of confusing techniques on offer some of which even I don't understand. A simple equal break option and a rounded break option should be the default and an 'advanced' link takes users onto those other options if needs be. By equal break I mean for a range of 0 to 307 it would offer to break the data into classes, into 0 - 103.33, 103.33 - 206.66, 206.66 - 307. By rounded equal break it would come up with some rounded suggestions like 0 - 100, 100 - 200, and 200 - 307. I hate all the decimal places in keys, it makes it really difficult to understand what the rough size of the breaks are.
  2. The key isn't obvious enough (you can just spot it as a bar in the bottom right corner)
  3. Give the countries (or polygons) a mouse rollover behaviour so that we can see the extent of the country when a mouse is positioned over it.
  4. And a really minor one: The visibility button for the layer should have a rollover behaviour to do with its border rather than becoming 'ungrayed', gray should = invisible, ungray should = visible and grayness should not indicate anything else.
But overall its already in great shape, I look forward to experimenting with it further when the new functionality is added.

UUorld is also one to watch but requiring a download is a big disadvantage and I'm not that impressed by 3D thematic maps which is their major advantage over GeoCommons.


Steve Chilton said...

I have been quite impressed by Geocommons tools. I wrote a very brief comparison of Finder/Maker, and GmapMaker, and Thematic Mapping Engine in latest SoC Newsletter []. Also gave feedback to Geocommons about not being able to set bipolar variables, which they acknowledged was on the TODO list.
Cheers, Steve

Anonymous said...

I'm not a professional in this are, but I thought the term was "choropleth". Am I mistaken?

Rich Treves said...


I did check the spelling but it seems my original spelling is common on the web so I missed the error. Re-edited post to correct for this.