[mkgmap-dev] special case where splitting fails without a log message

Tue May 25 17:46:54 BST 2021

Hi Gerd

Patch attached that I hope fixes the splitting problem.

I haven't looked at your change yet, but your split-failed.osm test
had, and needed, lots of points visited twice and I don't see how this
can, or should, be avoided.

Ticker

On Tue, 2021-05-25 at 15:56 +0000, Gerd Petermann wrote:
> Hi Ticker,
> 
> with the attached patch ShapeMerger avoids to produce shapes where
> more than the start point is visited twice.
> This produces much larger img files (even larger than trunk) but
> PolygonSplitter doesn't complain.
> 
> I have to find out what GpsMapEdit means with "has a jitter". Maybe
> only those are problematic.
> 
> Gerd
> 
> 
> ________________________________________
> Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag
> von Ticker Berkin <rwb-mkgmap at jagit.co.uk>
> Gesendet: Dienstag, 25. Mai 2021 14:00
> An: Development list for mkgmap
> Betreff: Re: [mkgmap-dev] special case where splitting fails without
> a log message
> 
> Sorry - sea.zip!
> 
> On Tue, 2021-05-25 at 12:36 +0100, Ticker Berkin wrote:
> > Hi Gerd
> > 
> > I'm getting very confused by this. When I build with my trunk (some
> > filter order changes + a few others), I see a whole lot more that
> > JOSM
> > shows. It and your 6324001.img just show a central bit. Looking
> > with
> > GPSMapEdit with "Highlight Polygon Contours". I also see areas
> > where
> > all islands are inverted.
> > 
> > I'll undo my trunk changes and look again.
> > 
> > Does JOSM have self-intersection checking?
> > 
> > Was the gpx trace hi-res (30bit) and then this kept when generating
> > the
> > osm. If not, then I'd expect problems.
> > 
> > Ticker
> > 
> > 
> > On Tue, 2021-05-25 at 11:18 +0000, Gerd Petermann wrote:
> > > Hi Ticker,
> > > 
> > > I didn't investigate the details. I've created the osm data by
> > > converting a gpx back to osm. I guess in the original input
> > > duplicate
> > > points are identical. I found more such cases where parts are
> > > removed.
> > > 
> > > Gerd
> > > 
> > > 
> > > ________________________________________
> > > Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im
> > > Auftrag
> > > von Ticker Berkin <rwb-mkgmap at jagit.co.uk>
> > > Gesendet: Dienstag, 25. Mai 2021 12:51
> > > An: Development list for mkgmap
> > > Betreff: Re: [mkgmap-dev] special case where splitting fails
> > > without
> > > a log message
> > > 
> > > Hi Gerd
> > > 
> > > OK - I've reproduced this. Is split-failed.osm self-intersecting?
> > > I'm
> > > not sure how to tell from Josm, but it looks like it isn't. I get
> > > the
> > > messages from shapeSplitter because it thinks it is and then the
> > > result
> > > is not good - as expected.
> > > 
> > > I'll investigate more.
> > > 
> > > Ticker
> > > 
> > > 
> > > On Tue, 2021-05-25 at 10:04 +0000, Gerd Petermann wrote:
> > > > Hi Ticker,
> > > > 
> > > > while looking at the problems with sea I found this case where
> > > > ShapeSplitter removes a small part of an island from a self
> > > > -intersecting polygon in res 24.
> > > > Compiled with mkgmap from trunk, default style and no options.
> > > > 
> > > > Look at 67.6742611, 14.6783525
> > > > 
> > > > Found this with some check code that compares the area of the
> > > > original polygon with that of sum of the parts.
> > > > 
> > > > Gerd
> > > > _______________________________________________
> > > > mkgmap-dev mailing list
> > > > mkgmap-dev at lists.mkgmap.org.uk
> > > > https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
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