[Boost-users] Sperical / geo coordinates question: crossing anti-meridian

Subject: [Boost-users] Sperical / geo coordinates question: crossing anti-meridian
From: John Lilley (john.lilley_at_[hidden])
Date: 2013-02-17 09:41:20

I am trying to determine if boost.geometry handles certain cases of spherical coordinates.  Suppose you have county outlines of Alaska.  The Aleutian Islands chain crosses the anti-meridian, and so contains latitudes that are in the ranges [ 180 - delta ... 180 ] and [ -180, -180 + delta ] where delta is < 20 degrees or so.

Simple (2D planar) point-in-polygon and polygon intersection algorithms fall down on these cases due to anti-meridian crossings and flipping between +/- values.  Does Boost geometry deal with these issues "correctly"?

I put correctly in quotes because there is some real ambiguity in the coordinate system (maybe the polygon really does wrap around the world?), but one could apply a "minimum perimeter" heuristic and normalize the polygons before performing the computation by moving the [ 180 - delta ... 180 ] range over to [ -180 - delta ... -180 ] or vice-versa.

Thanks,
john