I'm building a set of geofences to be installed on a GPS unit to track vehicles as they cross state lines. The list of geofences are simple latitude/longitude pairs, but each geofence needs to be a single polygon. The problem I'm having is that all datasets I find include a polygon for EVERY body of land (so every island off of Maine gets its own geofence).

What I'm looking for is something more like this: enter image description here

Notice how Massachusetts is a single geofence, as is Rhode Island and Connecticut. Including water in the geofence is fine.

I know this isn't possible for some states due to the Kentucky Bend, but I don't know if there are other exclaves (or enclaves) in the United States. In the case of Kentucky, I could simply have a Kentucky_Geofence_1 and Kentucky_Geofence_2, whereas I'd only need 1 for each of the three green states illustrated above.

As long as there's a way to export the data from a given format to JSON, XML, CSV, etc, I don't care what the file format is. I'm also not opposed to buying it, if it's already out there.

Again, because water doesn't matter, Alaska could look something like this:enter image description here

And Michigan could look something like this (but ideally with better resolution on the borders): enter image description here

(These images come from a custom Google Map I've been tweaking manually by dragging-and-dropping pins to manually create these, but it's going to take a LONG time to do them all, and it seems like this must have been done somewhere else already....)

  • @PolyGeo Why was "geofencing" not a correct tag for this? – Bing May 13 '17 at 20:39
  • What you are describing are multi-part polygons. What GIS software are you using, or is it only Google Maps that you are trying to do this with? – PolyGeo May 13 '17 at 20:41
  • I'm using Google Maps / Earth, but open to using any to be honest. I'm new to GIS, so if I'm using the wrong language I didn't know. I thought Geofences were polygons (one or many) which signify a geographical area. (I am trying to export these polygons for software triggering purposes...) – Bing May 13 '17 at 20:44
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    Actually I think you are looking for a concave hull around your multi-part polygon. You make no mention of geofencing in your question although I would imagine that a concave hull could be used by a geofencing application. – PolyGeo May 13 '17 at 20:45
  • @PolyGeo He seems to be after State legal (including maritime) boundaries as per gis.stackexchange.com/questions/240261/… – Midavalo May 13 '17 at 20:49

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