Flow Mapping

Cartographic Skills - Mod 9

This week's lesson was on Flow Mapping.  We created a distributive map depicting the 2007 immigration into the US from regions all around the world.  We had the choice of two different base maps to work with.  One had an inset choropleth map of the US classed to display the states by the percent of immigrants who settle there.  The other base map had the choropleth map overlaid on the world map.  I chose to go with the second option.  I had some concern the choropleth data might be a little difficult to see, but then I realized I would't really be able to make the image any bigger in the inset map if I was going to have room to display everything else at a reasonable proportion.  

In the end I think the choropleth map showed up just fine.  The scale bar, however, seemed obnoxiously large to me so I ended up cutting it down from 10,000km to 5,000.

This whole lab was in AI which was rather intimidating to me until I opened the layers up and saw they were fairly well laid out.  It was easy enough to gather all the components of the scale bar and group them all together under the continents layer.  Everything else was pretty well laid out.  The only layer issue I ran into was when I wanted to expand the map to fill in more of the frame and had to delete some of the little islands that really had no effect on the purpose of the map.  The finding and dragging them, element by element, to the next layer up in order to separate them out of the groups was, again, one of the most time consuming aspects of the whole lab.  

I was not looking forward to drawing the curved lines because I had tried that a few times before and had no luck, but after watching a couple of the videos that had been posted I felt a lot more confident tackling them.  I had a few false starts, but then I got the hang of it and was able to get through them all well enough.  My biggest problem was getting the two lines for North America to line up well enough with the straight line and arrow so they gave a smooth, continuous appearance.  Another problem there was trying to figure out how to divide the line up.  Originally I had subtracted Canada from the rest of the NA total and set the line weight proportionate to that, but then I realized Canada wasn't the only country north of the US included in the count so I just decided to divide the line 50/50 and left it at that.  I also wasn't real thrilled with the line weight for the line running from Oceana, but I didn't want to increase the line weight for Asia, with the largest amount of immigrants, because I didn't want to crowd out the rest of the lines that had to fit into that limited space.

Labeling the continents was simple enough since they were all large enough to select a large font size without running into any overlap issues.  I had already decided I was going to label my flow lines rather than create a separate legend since I didn't want to lose the space.  I tried selecting one of the lines to use the Type on a Path Tool, but the text kept coming in upside down.  I spent a bit of time trying to figure that out, but finally decided to just enter the text straight and rotate it to the line.  I placed all the text close to the continent it represented because I thought that made it clearer to the map reader.  

After this the rest of the map elements went in quick and easy and I got to the effects stage.  I had already decided I would like to raise the US choropleth map up just a bit to give it a little more emphasis, but when I did it offset it so much from the world map underneath that I found it somewhat distracting.  I tried making a few adjustments to see if I could minimize the effect, but AI was moving so slow and locked up a few times so in the end I gave up on that idea.  Though I think it would have looked pretty cool.  So my next step was to try to implement some effects on the flow lines.  I went round and round with this, changing the color from black to matching the color of the regions they represented, then finally settled on matching colors.  I think the black stood out a lot more, but it I thought it was too much, that it kind of washed out the rest of the map.  I decided to go for an inner glow and a shadow.  I wanted a brighter center, fading out to the darker color along the edge, but when I tried it that way it either didn't show up or it took over the whole width of the line.  When I tried the glow on the edge it was a similar experience, but at the lower setting where it was just around the edge it did seem to show up a bit so I left it at that.  With that done I added shadows to the lines and called it done.

Overall it was a rather enjoyable assignment.  I had a bit more time with this one to play with some of the AI tools and try different things and feel like I learned quite a bit with this.