Friday 19 December 2008

Simple is often better

When working with GIS boundaries, I'm often only really interested in them from a general point of view so that I can create simple choropleth maps. Also, if I'm trying to publish them over the web, there's no need to provide very accurate boundaries. Therefore, it's always useful to have different ways of simplifying boundaries. I have used various tools for this, including ET GeoWizards free tools and some of the in-built functionality of ArcGIS 9.x. However, the most convenient and flexible tool I've come across so far is MapShaper. They have an alpha testing version of their Flash-based interface here and it's really easy to use. There is a 16MB file size limit, but I've still found it to be very effective. It doesn't require much (if any) expert knowledge of GIS or of file formats, and you can simplify or smooth using a number of different methods (see images below). All in all, a very useful tool!