Module 9: Flow Line Mapping

This week's lab was about flow line mapping. Our objectives were to learn how to assess design issues for flow line mapping, to use Microsoft Excel to calculate proportional line widths, and to construct a flow line map using proper design techniques and using styling and visual effects. Flow maps show the movement of phenomena between locations, often using lines of varying widths to show the amount of movement. This week, our objective was to create a flow map of immigration to the United States from around the world. For this map, we used CorelDraw exclusively. The flow lines are easier to create in CorelDraw vs. ArcMap as they need to be hand drawn. Another reason to use CorelDraw is that we wanted our flow lines to have proportional thickness.

This was a really interesting lab in that I feel I have enough of a handle on CorelDraw to spend some time on some of the visual effects. I spent quite a bit of time looking at the different transparencies on the map background and getting one I liked. First, I needed to decide which basemap I wanted to use. I saw a few examples and saw a couple I really liked using the United States as the center with the continents around it, and I wanted to go with that idea. What I did to break apart the continents was to use Object Properties and select all the objects for a particular continent; they used different colors, so I mainly grouped them by color and matched the outline objects. I moved each continent a distance away from the United States layer, making sure to leave enough room for the essential map elements at the bottom. I used ColorBrewer to help select a good color scheme for the states in the United States layer. Once I had my continents and the United States placed as I wanted, I created the legend by using the text tab and the shape tool to create the text and rectangles. I then used Microsoft Excel and the equation:

Width of line symbol = (maximum line width) x (SQRT value / SQRT maximum value)

to find the proportional width of the flow lines. I went back to CorelDraw and created the flow lines and the text labeling the continents. I used drop shadow and extrusion to make the flow lines stand out more. I also used transparency on the main layer to give the overall map a more professional look. The transparency took a little bit, as there are different types, and I had to manually fiddle with the colors to minimize the washing out effect the transparency tended to have on my map.

I really enjoyed this lab. I learned a lot more about CorelDraw and am much more comfortable with the program now, and I'm looking forward to the next lab.