dr-jts
commented
6 years ago Good point, using the general intersection algorithm in InteriorPointAreais quite inefficient.
I think this would be improved with a simpler customized HorizontalLineIntersectionalgorithm, rather than trying to change the current overlay algorithm. Of course, this could be provided as a branch in Geomery.intersection by checking for an input of a horizontal line.
On the wish list is a ClipToRectangle algorithm, which might provide this capability as well. Although I suspect that an algorithm specifically for horizontal lines could be even simpler.
jandam
Geometry intersections = bisector.intersection(geometry); in InteriorPointArea::addPolygon uses general intersection algorithm. We know that bisector is horizontal LineSegment. So there can be specialized algorithm for horizontal/vertical lines. INTERSECTION in OverlayOp can be improved to use segments that fits to horizontal/vertical Interval intersection from both geometries. I think that other segments/monotone chains can be omitted. Example: Czech Republic polygon from OpenStreetMap ~80k nodes -- following can be eliminated if we use only segments/monotone chains that intersects with horizontal line ~22k monotone chains ~44k Mark&Sweep events
Possible issues/regressions I suppose that there can be some problems when SnapIfNeededOverlayOp fallback from OverlayOp to SnapOverlayOp.