Hi Gerd Any form of self-intersection might cause problems to ShapeSplitter. Not sure what you mean by "connected hole visited.." - I presume something like the outer edge of the shape is clockwise, with a cut leading to a hole that is also clockwise; for this to happen the in/out lines from the edge to the hole conceptually cross. I'm just running low-res-opt on BritishIsles with ShapeMergeFilter maxPoints=65535 to see if I can get a problem to work on. What is your test area? Also, the latest development versions of the suspect code areas are in different branches. Should I attempt to have a composite with the faster-mp bits of MP handling and low-res-opt version of ShapeMergeFilter? Your attached example looks OK and I wouldn't have expected it to cause any difficulties for the later versions of ShapeSplitter. A possible difficulty might be an almost horizontal line close to the in/out lines to the lower shape. I hope my attempt to allow a bit of tolerance where calculated points on the cut-line end up 1/2 HP units the wrong way round isn't causing other problems. Do you have this as an example I can test? Ticker On Sun, 2021-06-13 at 14:17 +0000, Gerd Petermann wrote:
Hi Ticker,
OK, my current understanding is that ShapeSplitter may fail to split 8-like shapes or shapes where the connected hole is visited in the "wrong" direction. Those problem cases are possibly created by 1) MultipolygonRelation.joinways() 2) MultipolygonCutter 3) ShapeMergeFilter (maybe)
Do you see a way to avoid them in those routines? Attached is another example that doesn't work.
Gerd