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We have multiple populations of patients spread out over geographic distances. For each population, we want users to easily define non-overlapping polygons. The outer borders are likely to be U.S County boundaries, if that makes any difference.

Essentially, I'd like for users to visually build groups of non-overlapping polygons and have the application provide us with sets of coordinates for each polygon. I would then be using the data in Google Maps. We currently have a method to identify patient's location by lat/long, using Google Maps API if the user needs to approximate the location.

Web-based software is preferred, but I'd consider a desktop package if the interface was easy enough for our users with minimal training.

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How do you currently store the patient data? It sounds like you need some type of spatial database. –  djq Sep 11 '12 at 20:28
Are you talking about building something like a Voronoi diagram –  RyanDalton Sep 11 '12 at 23:41
@celenius: updated the post to state that we're storing location by latitude/longitude. –  Jeff Bauer Sep 12 '12 at 0:44
@RyanDalton: A Voronoi diagram may be a mathematical explanation of what I'm trying to achieve, but from a user/use case perspective I'm looking for a means of constructing non-overlapping polygons and capturing the data as lat/long points. –  Jeff Bauer Sep 12 '12 at 0:52

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One approach could be to use OpenLayers to enable users to draw polygons onscreen, and then to store these polygons in a postgresql/postigs database, transferring the data using the WFS-T protocol. I would avoid using the Google API directly as it does not easily facilitate analysis.

I don't quite understand what you mean by 'non-overlapping polygons'; do you want users not to draw over existing polygons?

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Correct, I want adjoining polygons (polygons where the edges join), but do not want them placed over existing polygons. –  Jeff Bauer Sep 12 '12 at 15:45
That sounds like it might be easiest to check on the server side. A user can draw a polygon and then it could be submitted, then using PostGIS, the function ST_Intersect could see if there is any overlap. –  djq Sep 12 '12 at 15:55
The 'drawing tool' is what I'm looking for. We're currently investigating OpenLayers to see if it can fit the bill. –  Jeff Bauer Sep 13 '12 at 1:54
You've probably seen this: openlayers.org/dev/examples/draw-feature.html –  djq Sep 13 '12 at 2:58

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