[Google Maps API v2] Re: Algorithm to merge polygons

Thanks for providing the lead to the GPC library. I am trying to merge CA counties together and was having a challenge w/ the non-trivial problem.

However, I was able to get GPC to make it work w/ minimal effort.

Took the clipping example from the docs and modified the 2 input files with the lat/lng coords of 2 counties and then ran   gpc_polygon_clip(GPC_UNION, &subject, &clip, &result);

and it worked like a charm!

Thanks

Alex

On Thursday, May 3, 2007 7:21:38 AM UTC-7, John Coryat wrote:

Bratliff,

I've thought of a couple of avenues along those lines, like creating a
database of "borders" which could simplify the task, but in the end,
there are so many variables that a successful routine would not always
work.

There is a library called GPC that has a union function in it. It's
very complicated but functions fairly fast. I use it in the zipunion
application. It works pretty much 100% of the time. I created a set of
optimized polygons that combine rivers into zip code polygons to make
things easier.

-John Coryat

 http://maps.huge.info / http://www.usnaviguide.com

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