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

Wed May 26 05:46:44 BST 2021

Hi Ticker,

doesn't help much with the low-res-opt branch. I've attached a patch which contains my test code. It writes gpx files, so please modify the path.
I use it with in Eclipse a breakpoint on the line
log.error("split failed, ratio:", ratio);
to be able to load the GPX files into JOSM for further analyses.
I use it with my precomp-sea test-environment, see http://gis.19327.n8.nabble.com/precomp-sea-test-environment-tt5974624.html
options:
--output-dir=e:\ld  --gmapi --precomp-sea=f:\osm\sea.zip  --max-jobs=1 --style-file=e:\precomp-sea-check\sea-check -c e:\precomp-sea-check\tiles\template.args

or with the files in https://files.mkgmap.org.uk/download/507/xxx.zip
and options
--output-dir=e:\ld  --gmapi --generate-sea=multipolygon,floodblocker --max-jobs=1 --preserve-element-order --allow-reverse-merge  -c e:\xxx\template.args

If I got that right your algo has problems when the polygon goes through points A and  B twice, once in A-B direction and and again in B-A and the cut is between A and B?

I try to find efficient code to detect and avoid just those.

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 18:49
An: Development list for mkgmap
Betreff: Re: [mkgmap-dev] special case where splitting fails without a log message

Sorry - excess stuff in patch, correct one now.

Ticker

On Tue, 2021-05-25 at 17:46 +0100, Ticker Berkin wrote:
> 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
> > > > _______________________________________________
> > > > mkgmap-dev mailing list
> > > > mkgmap-dev at lists.mkgmap.org.uk
> > > > https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
> > > > _______________________________________________
> > > > mkgmap-dev mailing list
> > > > mkgmap-dev at lists.mkgmap.org.uk
> > > > https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
> > > _______________________________________________
> > > mkgmap-dev mailing list
> > > mkgmap-dev at lists.mkgmap.org.uk
> > > https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
> > _______________________________________________
> > mkgmap-dev mailing list
> > mkgmap-dev at lists.mkgmap.org.uk
> > https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
> > _______________________________________________
> > mkgmap-dev mailing list
> > mkgmap-dev at lists.mkgmap.org.uk
> _______________________________________________
> mkgmap-dev mailing list
> mkgmap-dev at lists.mkgmap.org.uk
> https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
-------------- next part --------------
A non-text attachment was scrubbed...
Name: report-split-problems.patch
Type: application/octet-stream
Size: 4117 bytes
Desc: report-split-problems.patch
URL: <http://www.mkgmap.org.uk/pipermail/mkgmap-dev/attachments/20210526/ebf2418f/attachment-0001.obj>