private PolyTree Union(IReadOnlyList<IReadOnlyList<TriangulationPoint>> input)
{
var landUnionClipper = new Clipper(Clipper.ioStrictlySimple);
landUnionClipper.AddPaths(input.MapList(x => x.MapList(UpscalePoint)), PolyType.ptSubject, true);
PolyTree landUnionPolyTree = new PolyTree();
landUnionClipper.Execute(ClipType.ctUnion, landUnionPolyTree, PolyFillType.pftNonZero, PolyFillType.pftNonZero);
return landUnionPolyTree;
}
