OpenCV is used here only for the "has dot/cross" aspect of feature detection (and it is very primitive still). The polygons themselves are more a work of R and GDAL.
It does vary from map to map although it is optimized for insurance maps (or any map made mostly with clearly delineated polygons). We've included a config file that you would modify to suit the maps you are working with. The current process takes advantage of preexisting features in mapping tools and adds feature detection (e.g. polygon is/isn't a building) and concave hulls.
We do welcome input and merge requests to improve the tool!
we (and when I say "we" I mean "you" because I'm not from the US) should be more concerned about the un-separation of church and state and less about the design
https://github.com/mgiraldo/tenprintcover-p5
This other project has some interesting geometric explorations:
http://variable.io/generative-covers/