Hi Ticker, my understanding is that Garmin software has no problems with this kind of self-intersection. In this particular case the problem could be solved in method MultipolygonRelation.joinWays(), as 4 ways are connected at the same point, but self-intersecting shapes are also possible as simple ways. While they are wrong for OSM they should be allowed for MapShape since Garmin allows them, too. A possible way to fix those shapes is something like this: Path2D.Double path = Java2DConverter.createPath2D(polygonPoints); path.setWindingRule(Path2D.WIND_EVEN_ODD); List<List<Coord>> shapes = Java2DConverter.areaToShapes(new java.awt.geom.Area(path)); So, maybe ShapeSplitter could do this with the input shape in case of error and try again with shapes? Gerd ________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Ticker Berkin <rwb-mkgmap@jagIT.co.uk> Gesendet: Dienstag, 8. Juni 2021 08:54 An: mkgmap-dev@lists.mkgmap.org.uk Betreff: Re: [mkgmap-dev] low-res-opt branch: error message from ShapeSplitter for self-intersecting multipolygon Hi Gerd The shape is a figure-of-8 so shapesSplitter needs to give some error. If this isn't an original OSM shape, it points to some problem with earlier processing, probably shape-merging. Although it might render (could be device dependent), further processing (eg overview merging) could come to grief. Ticker On 07/06/2021 10:24, Gerd Petermann wrote:
Hi Ticker,
okay, no problem, I'll work on the faster-mp branch in the mean time Maybe I'll merge it first into the low-res-opt branch.
Gerd
________________________________________ Von: mkgmap-dev <mkgmap-dev-bounces@lists.mkgmap.org.uk> im Auftrag von Ticker Berkin <rwb-mkgmap@jagit.co.uk> Gesendet: Montag, 7. Juni 2021 11:23 An: Development list for mkgmap Betreff: Re: [mkgmap-dev] low-res-opt branch: error message from ShapeSplitter for self-intersecting multipolygon
Hi Gerd
The shape I'm getting in my build has a major problem with a twist between the 2 parts. I'm having trouble reconciling it with the OSM map. I've attached the original shape trace.
I agree that some of the messages do need tweaking, but, in this cases there is a significant problem.
I'll consider the types of messages etc in the new version I'm working on.
I'm away for a few days and won't be able to do much remotely.
Ticker
On Mon, 2021-06-07 at 07:22 +0000, Gerd Petermann wrote:
Hi Ticker,
please check https://files.mkgmap.org.uk/download/512/63240024.o5m with (unpatched) r4756 and these options --generate -sea=multipolygon,floodblocker --preserve-element-order --order-by -decreasing-area --allow-reverse-merge
Produces an error message SCHWERWIEGEND (ShapeSplitter): e:\osm_out_work\norway\20210511_095323\63240024.o5m: Vertical split 36691968 failed on shape at http://www.openstreetmap.org/?mlat=65.979056&mlon=12.308790&zoom=17 P ossibly a self-intersecting polygon for this invalid multipolygon : https://www.openstreetmap.org/relation/5294624
The result doesn't look wrong, so I think there should either be no error message or we need code to remove those self-intersections or ignore invalid MP like that?
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