Wednesday, 16 April 2008

Flow Mapping Frenzy

One of the GIS areas I'm really interested in is flow mapping, or dynamic mapping as some people call it. I did a lot of this in my PhD and am now in the process of writing a paper about it. This is also part of the reason I'm getting into VBA. Here's an example:

This map is an extract from a much, much larger dataset that has nearly 1 million flow lines in it. On the left the image shows inflows to Manchester from 2000 to 2001 and the other one shows outflows from 2000 to 2001. I like to think of this as the migration footprint of Manchester and even though many of the lines represent very little movement, the spatial extent is quite large. The message here, I suppose, is that everywhere is connected to everywhere else, but near places moreso (Waldo Tobler's First Law, anyone?). So, I'm into flow mapping, but only really as one more way of helping us to understand the way our world works. Although, I do have to admit that the nerd in me actually enjoys the technical side of it all too. There's really lots of different ways to do this kind of thing in GIS, but I used ArcGIS 9.x and Alan Glennon's Flowtools. I also hear that ONS are doing something similar to this with their new data visualisation unit - so have to see how that develops in due course.

My next paper is going to be much less technical. My post-PhD publication plan is to get 4 papers from my thesis and so far I've completed two quite technical pieces. Now I want to get back to the actual topic itself (spatial effects of regeneration initiatives in North West England). I might write something here about this soon...