[mkgmap-dev] Large polygons and subdivisions

Sat Sep 10 17:17:03 BST 2016

Hi Gerd

Just noticed that I didn't reply to the list either!

I need to change mergeShapes so that it only re-joins polygons that got
split by MultiPolygonRelation, because the sorting has to be by
original area, otherwise, across a subdivision join, areas might be in
different order.

The gmapsupp.img is 0.2% bigger (probably mostly the effect of not
doing mergeShapes)

When I've changed mergeShapes I need to tidy up my changes and remove
quite a lot of diagnostics and I'll post a patch

Regards
Ticker

On Sat, 2016-09-10 at 15:40 +0000, Gerd Petermann wrote:
> Hi Ticker,
>  
> sorry, just noted that I did not reply to the list.
> Why do you have to disable the mergeShapes?  
> What is the effect on img size?
> I don’t have much time for mkgmap now as I am working on some patches
> for JOSM.
> Feel free to post Patches to the list, maybe others like them, too.
>  
> Gerd
>  
> Von: Ticker Berkin
> Gesendet: Samstag, 10. September 2016 17:31
> An: Gerd Petermann
> Betreff: Re: AW: [mkgmap-dev] Large polygons and subdivisions
>  
> Hi Gerd
> 
> I've done this and haven't found any side effects yet. I had to track
> the original full area of polygons and sort on this (and disable
> MapBuilder.mergeShapes). It seems to fix the problems I was having.
> 
> Ticker
>  
> 
> On Fri, 2016-09-09 at 15:27 +0000, Gerd Petermann wrote:
> > Hi Ticker,
> >  
> > Yes, that’s what is happening and I hink it is intended. You may
> try
> > to add code that cuts the polygons
> > when subdivs are split in MapSplitter, but maybe this will have
> side
> > effects.
> >  
> > Gerd
> >  
> >  
> > Von: Ticker Berkin
> > Gesendet: Freitag, 9. September 2016 17:06
> > An: mkgmap development
> > Betreff: [mkgmap-dev] Large polygons and subdivisions
> >  
> > Hi
> > 
> > I'm getting inconsistent displays in, for example, an area with
> woods
> > and a large sports area, also area of wetland with many lakes (not
> > expressed as outer/inner relation). 
> > 
> > From my reading of the code, the problem occurs where the larger
> > polygon crosses a subdivision boundary. It seems that its full area
> > is
> > allocated to just 1 subdivision, even though it might span many. 
> > 
> > In the subdivision to which the large area is allocated, it is
> drawn
> > first, then the small areas are drawn, overwriting nicely (because
> > the
> > shapes in the subdivision have been sorted by decreasing size). But
> > in
> > an adjacent subdivision the small areas are overwritten.
> > 
> > Shouldn't polygons be split on subdivision boundaries? I can't see
> > any
> > code that does this.
> > 
> > Regards
> > Ticker Berkin
> >   
> > _______________________________________________
> > mkgmap-dev mailing list
> > mkgmap-dev at lists.mkgmap.org.uk