[geos-devel] Change in overlay failure handling heuristic

[Sandro Santilli]

Dear overlayers and exception catchers,

as of r3552 the heuristic used for trying to get to some kind of overlay
result in case of robustness issues (BinaryOp) has been augomented
to perform an additional check to the results of snapping the input
geometries each-other, and running a self-union whenever such snapped
geoms result invalid.

Such behavior is to fix the cases in which snapping
creates self-intersections thus introducing problems
for later computations.

It is known to fix at least one case:
http://trac.osgeo.org/geos/ticket/488

Additional work is required to check for validity, but you'd never
get to that point unless the _original_ run (w/out snaprounding)
worked.

Please test the new behavior as I plan to ship it with upcoming 3.3.2.
Thank you.

--strk; 

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