Easy way to fill in irregular zone areas

I have begun working on a Cthulhu Wars module (with the permission of Sandy Petersen), and since it’s an area map movement game, I began creating Zones on the map board. I found that the “Define shapes” tool is fiddly, to say the least. It was going to take me forever to define all the different regions for umpteen different boards! I can’t imagine how much time has been spent designing the modules for similar games. I did a quick perusal of the forums here and learned that this seems to be a known issue.

So, I am happy to report that I found a much quicker method. I’ll post a short version here in the hopes that it helps someone.


Gimp (although I am sure you can do the same thing in Photoshop and similar tools).
A text editor with the ability to do regex replacements (for example, Komodo Edit), or alternatively, a script.


  1. Use Gimp to open the map file (important: it must be the same image with the same dimensions as the one you are using in your module!). Select the area you want to define as a Zone using whatever selection/drawing tool you prefer. Export that selection as an SVG path. See this link for easy step-by-step instructions.

  2. Open the SVG file in a text editor. The part you want is the coordinates for the Selection path. This will be the long block of floating point number pairs between the last “C” and the “Z”. Copy just that block of numbers.

  3. Get rid of all extra white space. E.g.,

s/\s{2,}/ /
  1. Get rid of the decimal points and floating point digits. E.g.,

You now have a set of coordinates you can copy and paste directly. Add your Zone, choose Define Shape, and then Set Coordinates directly. Copy the coordinates into that text field. You should now see the exact selection you made earlier in Gimp appear on your map.

Hope this is helpful.

I nominate to have this set as a sticky post. Good information.

Very smart idea!

I created a quick Perl script to automatically turn the exported SVG file described above into a text file containing the coordinate pairs you can paste into the Set Coordinates box.

I’m not sure where such resources can be uploaded (the “upload attachments” box wouldn’t let me upload a script). I suppose I could just copy and paste the code.