Hi Ticker,

I've probably not understood the problem before. I've added test code to find 
situations where the ShapeSplitter complains and I found a rather simple case 
where the ShapeMerger produces a self-crossing shape (see attached gpx). Now I 
have an idea what to look for.

Gerd

________________________________________
Von: mkgmap-dev <[email protected]> im Auftrag von Gerd 
Petermann <[email protected]>
Gesendet: Donnerstag, 27. Mai 2021 18:14
An: Development list for mkgmap
Betreff: Re: [mkgmap-dev] special case where splitting fails without a log 
message

Hi Ticker,

I've attached my current state of work as patch for the branch.
It fixes some bugs and merges shapes in a way that is less likely to produce 
long connections to islands.

I think the main problem for shape splitter is when such a connection has a 
U-shape and the cut goes through it horizontally. But I'm just guessing...

Gerd

________________________________________
Von: mkgmap-dev <[email protected]> im Auftrag von Gerd 
Petermann <[email protected]>
Gesendet: Donnerstag, 27. Mai 2021 17:59
An: Development list for mkgmap
Betreff: Re: [mkgmap-dev] special case where splitting fails without a log 
message

Hi Ticker,

JOSM shows the islands properly when you zoom in. And yes, it shows water on 
both sides of the connecting lines. Very simiar to the Garmin renderer.
Does that help?

Gerd

________________________________________
Von: mkgmap-dev <[email protected]> im Auftrag von Ticker 
Berkin <[email protected]>
Gesendet: Donnerstag, 27. Mai 2021 17:48
An: Development list for mkgmap
Betreff: Re: [mkgmap-dev] special case where splitting fails without a log 
message

Hi Gerd

I'm confused. After mp hole cutting and shape merging, I expect a
single closed way that will have in/out lines, probably on top of each
other, to connect each area that was a hole, eventually, to a point on
the outside of the shape.

However, JOSM does show the water band on the outside of what were the
islands, and on both sides of the joining lines.

Ticker

On Thu, 2021-05-27 at 15:10 +0000, Gerd Petermann wrote:
> Hi Ticker,
>
> yes, sure. I've converted a gpx output to OSM. All polygons with
> holes are not valid OSM ways, but they are very normal as MapShape.
> Validator doesn't help much with these polygons.
>
> Gerd
>
> ________________________________________
> Von: mkgmap-dev <[email protected]> im Auftrag
> von Ticker Berkin <[email protected]>
> Gesendet: Donnerstag, 27. Mai 2021 17:06
> An: Development list for mkgmap
> Betreff: Re: [mkgmap-dev] special case where splitting fails without
> a log message
>
> Hi Gerd
>
> JOSM gives a self-crossing way validation error on this.
>
> Ticker
>
> On Thu, 2021-05-27 at 14:53 +0000, Gerd Petermann wrote:
> > Hi Ticker,
> >
> > no need to hurry ;)
> > Here is one:
> > https://files.mkgmap.org.uk/download/508/water.osm
> >
> > Gerd
> >
> > ________________________________________
> > Von: mkgmap-dev <[email protected]> im Auftrag
> > von Ticker Berkin <[email protected]>
> > Gesendet: Donnerstag, 27. Mai 2021 16:47
> > An: Development list for mkgmap
> > Betreff: Re: [mkgmap-dev] special case where splitting fails
> > without
> > a log message
> >
> > Hi Gerd
> >
> > next patch also has a problem - sorry to waste your time.
> > Can I have your test data.
> >
> > Ticker
> >
> > On Thu, 2021-05-27 at 14:33 +0000, Gerd Petermann wrote:
> > > Hi Ticker,
> > >
> > > with my current test environment the patch doesn't improve the
> > > result.
> > > It reports some errors (the old code didn't always detect them)
> > > and
> > > eithers add or removes parts of the heavily merged shapes.
> > >
> > > I've inspected one shape and found no obvious problem. No point
> > > is
> > > visited more then twice, but 167 points are visited twice. Let me
> > > know if you need the data.
> > >
> > > Gerd
> > >
> > > ________________________________________
> > > Von: mkgmap-dev <[email protected]> im
> > > Auftrag
> > > von Ticker Berkin <[email protected]>
> > > Gesendet: Donnerstag, 27. Mai 2021 16:09
> > > An: Development list for mkgmap
> > > Betreff: Re: [mkgmap-dev] special case where splitting fails
> > > without
> > > a log message
> > >
> > > Thanks Gerd, that works for me
> > >
> > > Ticker
> > >
> > > On Thu, 2021-05-27 at 12:54 +0000, Gerd Petermann wrote:
> > > > Hi Ticker,
> > > >
> > > > I first convert the gpx layer to a data layer, then add the tag
> > > > natural=water
> > > > Next execute validator which will complain that the way is not
> > > > closed.
> > > > Right click on that warning allows to "zoom to problem" .
> > > > This tells you where the first point is.
> > > >
> > > > In the "OSM data" preferences I've enabled "Draw segment order
> > > > numbers on selected way"
> > > >
> > > > Hope this helps.
> > > >
> > > > Gerd
> > > >
> > > > ________________________________________
> > > > Von: mkgmap-dev <[email protected]> im
> > > > Auftrag
> > > > von Ticker Berkin <[email protected]>
> > > > Gesendet: Donnerstag, 27. Mai 2021 14:21
> > > > An: Development list for mkgmap
> > > > Betreff: Re: [mkgmap-dev] special case where splitting fails
> > > > without
> > > > a log message
> > > >
> > > > Hi Gerd
> > > >
> > > > Trying to use JOSM to decide if a gpx trace represents a self
> > > > -intersecting polygon is difficult. Is there a way of forcing
> > > > it
> > > > to
> > > > consider it closed and then check itself? Failing that, number
> > > > the
> > > > points or segments somehow.
> > > >
> > > > Ticker
> > > >
> > > >
> > > > _______________________________________________
> > > > mkgmap-dev mailing list
> > > > [email protected]
> > > > https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
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> > > > mkgmap-dev mailing list
> > > > [email protected]
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Description: o_hp.gpx

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