[mkgmap-dev] [Patch V1] Subdivision width is 36627 at 3230916/1236133

Thu May 3 22:19:54 BST 2012

Hi WanMil,

> Date: Thu, 3 May 2012 22:10:57 +0200
> From: wmgcnfg at web.de
> To: mkgmap-dev at lists.mkgmap.org.uk
> Subject: Re: [mkgmap-dev] [Patch V1] Subdivision width is 36627 at	3230916/1236133
> 
> Ok, I missed that the split routine is called only if the maxdimension 
> is larger than max width/height.
> 
> Why do you use maxSize-MapSplitter.MIN_AREA_DIMENSION(10) as max dimension?

I think any large value smaller than maxSize will work. There is no good reason to use this constant, I forgot to remove it
when I tried to create a test case for the problem described in your picture. I failed to create such a case, but I think it is 
possible to hit that case, and my patch doesn't solve it.

Gerd

> 
> WanMil
> 
> > Hi WanMil,
> >
> > makeSplittable is called very seldom, and the number of points is typically
> > also small,
> > so performance really doesn't matter here (at least not with my test cases).
> > I did not want to modify the points of the original MapLine object to avoid
> > side effects.
> > I did also want to avoid complex calculations for the new points, so I
> > simply always add one
> > new point in the middle of the existing ones.
> >
> > Adding the calculated points to the List coords that is used to create the
> > new MapLine
> > objects might be an option, but I did not find a simple way to handle the
> > loop control for
> > cases where we have to add multiple points.
> >
> > So, in short, I didn't find a better solution.
> >
> > Regarding the other changes in the patch:
> > I agree that the code is complex, but I did not see a reason for a complete
> > rework.
> >
> > Gerd
> >
> >
> >
> >
> > WanMil wrote
> >>
> >> Hi Gerd,
> >>
> >> the LineSizeSplitterFilter patch is a good idea. After reading the code
> >> I am not sure if the other changes work for all situations (just because
> >> the things are quite complex there). I think I will wait for at least
> >> one week if someone complains...
> >>
> >> Anyhow I want you as our performance guy to have a look on the
> >> LineSizeSplitterFilter :-) makeSplittable always copies all points
> >> although it changes them in very rare cases.
> >> Can you check (and implement) the following approach?
> >> ListIterator<Coord>  iter = points.listIterator();
> >> Check all subsequent points. If maxWidth or maxHeight is exceeded
> >> calculate the number of points that must be added (something like int
> >> split = Math.max(realWith/maxWidth, realHeigh/maxHeight))
> >> Go back one point in the list iterator and add the additional points to
> >> the list iterator.
> >>
> >> WanMil
> >>
> >>> Hi all,
> >>>
> >>> attached is a corrected version of the patch. Please note the change in
> >>> the
> >>> logger initialisation for
> >>> LineSizeSplitterFilter. I guess the old code was not intended.
> >>>
> >>> Gerd
> >>> http://gis.19327.n5.nabble.com/file/n5680163/subdivision_width_v2.patch
> >>> subdivision_width_v2.patch
> >>>
> >>>
> >>> GerdP wrote
> >>>>
> >>>> Hi Marko,
> >>>>
> >>>> unfortunately it produces new errors for a tile in south-america which
> >>>> wasn't in my test data yesterday, so it should not be used yet :-(
> >>>>
> >>>> Gerd
> >>>>
> >>>>
> >>>>
> >>>>
> >>>> Marko Mäkelä wrote
> >>>>>
> >>>>> Hi Gerd,
> >>>>>
> >>>>>> http://gis.19327.n5.nabble.com/file/n5672934/subdivision_width_v1.patch
> >>>>>
> >>>>> Thanks, this removed the message. I did not test the resulting map yet,
> >>>>> but I will do that when downloading and compiling the next map extract.
> >>>>>
> >>>>> 	Marko
> >>>>> _______________________________________________
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> >>>>> mkgmap-dev at .org
> >>>>> http://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
> >>>>>
> >>>>
> >>>
> >>>
> >>> --
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> >>> Sent from the Mkgmap Development mailing list archive at Nabble.com.
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> >>
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> >>
> >
> >
> > --
> > View this message in context: http://gis.19327.n5.nabble.com/Patch-V1-Subdivision-width-is-36627-at-3230916-1236133-tp5672934p5682325.html
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