Re: [jts-dev] Struggling with polygon topology again. Overlapping inner

[Martin Davis <mtnclimb@xxxxxxxxx>]

On Thu, Sep 22, 2016 at 2:45 PM, Phil Scadden <p.scadden@xxxxxxxxxx> wrote:

>1. For polygons which have "loops" in their shell, buffer(0) may FAIL because it keeps only one of the loops (and may choose the smaller one).

>2. For polygons with rings that touch but do not cross, buffer(0) should produce VALID output

That is excellent information. What about the more common case of internal rings that overlap?

Hole rings that overlap should also produce valid output, but perhaps not in the way you might expect.  The entire area covered by the holes will be merged into a single hole (which makes topological sense, since the hole areas were exterior to the polygon to begin with).