[geos-devel] bad input data or robustness issue?
russell at strong.id.au
Mon Mar 3 04:43:36 EST 2008
I'm trying to dissect up a bunch of nearly round overlapping polygons,
ie.. trying to find areas of overlapping radar coverage given a set of
radar locations and ranges.
However, trying this with a few polygons, testing each case I can think
of works very well. Add a few more and I get all sorts of errors including:
* side location conflict
* stuck in endless loop ( due to intersect and difference operations
that produce the same polygons as we started with )
* non-noded intersection
* no outgoing dirEdge found
I've included some test code that shows all of these, ( uncomment
various tests in main ). If anyone has some time to run these and
comment I'd appreciate it. I've spent 5 solid days on it and I'm out of
it basically works like this:
I keep a link list of "areas" which contain a geometry. I then compare
each geometry against each other ( except for self ). If it intersects,
I add the intersection and the 2 differences to the list (if they exist)
and remove the source areas. I keep going until I've compared every
area against every other area and found no non-empty intersections.
One other thing that I found was the Overlaps can return true but the
intersection of the two polygons returns true for isEmpty?!?!? (I was
using overlaps instead of intersects in the split_areas comparison)
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