21 replies to this topic

[frax]

Hi,

I need to design a flow map, that should come out something like an airline route map. It is more for the graphic design/looks rather than communicating something quantitative. The thing is that there are cases where there are many units connecting points A and B - and I was curious if there was an easy way to represent this as parallel arching lines - somewhat like an airline route map.

Software at hand (either works): Illustrator + ArcGIS.

[radek]

you might try here or here

[ceicher]

Hi,

There's also a post on this topic by Charlie Frye on the ESRI Mapping Center/Centre

http://blogs.esri.co...e-to-place.aspx

-Cory

[razornole]

Hello Frax,

Have you tried the path-offset command in Illy? I use AutoCAD for my flow maps b/c it produces better offsets around curves, but as you mentioned you are not quantifying anything. The basic offset command in Illy sounds to me as the perfect tool for the job. The offset command in Illy creates a closed path so it is easy to fill. If you need multiple colors for your fills then you could quickly create a Live Paint Object.

Hope this helps,
kru

[frax]

Let me clarify a bit... maybe the best way is to add an image...

So I have a yarn of directional connections. Sometimes there are multiple connections between two points, and sometimes the connections go both ways. I haven't experimented much with arrowheads yet, I think that will get to messy though. I was thinking about using color (gray at origin, red at destination) to show directionality, but we'll see how that goes. I need to tinker a bit with this.... But my main goal is to see if I can make some of the arch so that the don't overlap. The offset path in Illustrator doesn't do this, I think the only way to do this is to go in manually and do that. I was also curious if I could make those that show multiple connections (it is number of people that traveled between points) not overlap, and be parallel arches...

Attached Files

•  Clipboard01.png   46.49K   64 downloads

[gregory]

Also worth to have a look at:
http://graphics.stan...n/code/flowmap/

[razornole]

Thanks,

I have a much better understanding of what you are trying to map, but I don't have a solution. That is a lot of data, and I am stumped on how to represent it efficaciously.

Can you somehow make your point data areal data? I think adding gradients to your lines would make it more confusing, but I guess that I would have to see it first.

As far as the curves are concerned, keep in mind that people tend to perceive straight lines as a more direct route when they are used simultaneously with curved lines. You might not want that perception.

I would like to see the outcome of this project.

kru

[frax]

For Illy - got this from the Adobe forums - the 'Arc' effect is what I was looking for. Just need to play with it a bit more. The offset path effect just creates a parallel line, without keeping the end-points, so that is out of the question.

So - for a lot of arrows - what other than arrowheads can I use to show directionality? I am experimenting with color (gray at start, red at end point) and width (wide - narrow at end).

[ceicher]

Hi,

Looking at your data, this could also be a perfect situation to use an interactive map. Not sure if that delivery method is possible for your customer.

I worked on something like this a few years ago. You can view the result in Google Earth.

 southamericatrade.jpg   67.97K   48 downloads

The example is with trade (exports) between 2 countries. We found export data online from all countries in S. America to all countries in S. America. In the interactive map, only show trade volumes from Country A to Country B, C, D, etc. are shown when you hover over Country A. Other lines are not shown. This reduces visual clutter and lets user focus on the information they want to see.

About: http://www.thetimone...ogle_trade.html
More About: http://www.gearthblo...h_american.html
Download (view in Google Earth): www.thetimoneygroup.com/sa/SA_trade.kmz
As others said, mapping flows is an interesting challenge. If you need a static map, I would recommend some type of aggregation strategy. Ask yourself what information is most valuable, and aggregate/symbolize to show only that information.

Good luck,

-Cory

Edited by frax, 28 May 2010 - 09:45 AM.
fixed link

[frax]

After discussions with the client, we are focusing on not showing too much in the static map - just a ball of yarn, and skipping the directionality.

But then we will do an interactive Google Earth version as well - where we can play more with interactivity.

So that is where it's at!

[CHART]

You might want to look up Rhumb lines. This would give a "realistic" arc to your travel lines

Attached Files

•  rumb.gif   8.46K   28 downloads

[Alf]

I also think the same, change the projection to curved lines go, this is the function of the Mercator projection that the routes are laid out in straight lines.

[frax]

Hi - there is no requirement that the lines should be realistic. They are not really travels - they represent exchanges between universities around the Arctic, so the actual travels would be routed elsewhere.

[AndrewM]

I don't know if it will help but you could take a look at Gephi . It's a free, open source piece of software for visualising network and relationship data. The site I first saw it on described it as 'photoshop for graphs'!

I've not really had the chance to try it out yet, but it may be worth looking at.

[l.jegou]

Hello, perhaps not useful in your case but i think it's worth mentionning : there's a flow map layout based on the prefuse software package :

http://graphics.stan...low_map_layout/