[mkgmap-dev] Problems with sea in overview map

Mon May 24 10:53:46 BST 2021

yes I know - some version last week or so was horrible in this regard. I
thought this happened because of trying to make the overview map smaller -
so I just wanted to note that the size here is less important.

On Mon, 24 May 2021 at 11:29, Gerd Petermann <
gpetermann_muenchen at hotmail.com> wrote:

> Hi Felix,
>
> white triangles in the sea are obvious errors and therefore I want to fix
> this. The number of points is not the interesting point, it is about
> keeping the important points and removing unnecessary ones. This doesn't
> work well. The same problem occurs with other complex multipolygons that
> have many inners, but you don't see them often in the alps ;)
>
> Gerd
>
> ________________________________________
> Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von
> Felix Hartmann <extremecarver at gmail.com>
> Gesendet: Montag, 24. Mai 2021 11:07
> An: Development list for mkgmap
> Betreff: Re: [mkgmap-dev] Problems with sea in overview map
>
> I feel that there is not too much need to get the size of the overview map
> down. Even for Asia continent map there is enough room. So it is better to
> make sure it looks nice - than smallest size.
> Also for resolution higher than overview map - it is usually not too
> important. Most people are navigating on land - so sea does not have to be
> rendered as often on your GPS device compared to land and roads. Meaning
> for >90% of Garmin mkgmap created map users it is not too often that you
> have a complex sea in your map. Even if you live on a mid sized island -
> say Cyprus or so - most of the time you do not have much sea on your GPS
> device.
> The recent work on reducing road complexity was much more important in
> real world use than what can be achieved by reducing sea complexity. Just
> my opinion. Of course nice if there is an improvement - but compared to
> land features for most users for sea it is not too important to reduce the
> points. The changes recently made did make quite a big difference in speed
> when zooming out / panning the map on my Oregon or etrex devices. For sea
> there is much less to be gained. Of course it is never bad to see some
> improvements - but it is less important. On PC / notebook - usually the
> processor should be plenty fast for drawing the map (plus the cache of
> Basecamp)..
>
> On Mon, 24 May 2021 at 08:52, Gerd Petermann <
> gpetermann_muenchen at hotmail.com<mailto:gpetermann_muenchen at hotmail.com>>
> wrote:
> Hi Ticker / all,
>
> it seems I've looked at the wrong test files. I've tested with a few more
> input files and now I see large white triangles with the branch version
> 4736 while trunk 4735 doesn't show them.
> Looks like a problem with preserving points or maybe special cases with
> ShapeSplitter...
>
> Gerd
>
>
>
> ________________________________________
> Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk<mailto:
> mkgmap-dev-bounces at lists.mkgmap.org.uk>> im Auftrag von Ticker Berkin <
> rwb-mkgmap at jagit.co.uk<mailto:rwb-mkgmap at jagit.co.uk>>
> Gesendet: Samstag, 22. Mai 2021 13:30
> An: Development list for mkgmap
> Betreff: Re: [mkgmap-dev] Problems with sea in overview map
>
> Hi Gerd
>
> I've been doing experiments on tiles with much more sea and islands
> (tests before only had a bit of sea and lots of city).
>
> With my re-ordering I get a very slightly smaller main tile (4096 bytes
> in 5614K) and larger osmmap.img (34304 vs. 25088)
>
> In both cases I'm getting quite a few shapeSplitter messages where it
> finds inconsistencies in the line directions across the split-line;
> normally due to self-intersection. These are happening in both the main
> tile generation and the overview combining.
>
> Once shapeSplitter has generated this type of warning it is
> indeterminate which is shape and which is hole, so I'd expect gaps in
> the rendering.
>
> I think trunk had eradicated split/self-intersection problems in the
> tile processing, including the ovm_ file generation.
>
> I'm not sure about the overview combiner as, in my standard map-build,
> I don't merge shapes.
>
> Ticker
>
> On Fri, 2021-05-21 at 16:41 +0000, Gerd Petermann wrote:
> > Hi Ticker,
> >
> > I tried this patch with r4734 and I see no improvements. Maps are
> > larger, more white rectangles in sea.
> >
> > Maybe my recent changes don't work well with yours? Do you have an
> > example where it improves something with r4734?
> >
> > Gerd
> >
> > ________________________________________
> > Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk<mailto:
> mkgmap-dev-bounces at lists.mkgmap.org.uk>> im Auftrag
> > von Ticker Berkin <rwb-mkgmap at jagit.co.uk<mailto:rwb-mkgmap at jagit.co.uk
> >>
> > Gesendet: Freitag, 21. Mai 2021 18:10
> > An: Development list for mkgmap
> > Betreff: Re: [mkgmap-dev] Problems with sea in overview map
> >
> > Hi Gerd
> >
> > I'd been doing some investigation of filters ordering (based on
> > trunk).
> > I'd also done the pre-filtering of lines & shapes by minRes.
> >
> > My conclusions are:
> >
> > Shapes:
> > It is better to run SizeFilter after RemoveObsoleteFilter.
> > It is more efficient to run DP filter after both of these.
> >
> > Lines:
> > LineSplitterFilter should be run after everything that can remove
> > points.
> > It is more efficient to run DP after RemoveObsoleteFilter.
> >
> > I've adapted my changes into a patch for the low-res-opt branch,
> > along
> > with removal of some resolution tests that are now redundant.
> >
> > For the contourFilters, I've left DP as the first filter but moved
> > LineSplitter as for the normalFilters
> >
> > Ticker
> >
> >
> > _______________________________________________
> > mkgmap-dev mailing list
> > mkgmap-dev at lists.mkgmap.org.uk<mailto:mkgmap-dev at lists.mkgmap.org.uk>
> > https://www.mkgmap.org.uk/mailman/listinfo/mkgmap-dev
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>
> --
> Felix Hartman - Openmtbmap.org & VeloMap.org
>
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>

-- 
Felix Hartman - Openmtbmap.org & VeloMap.org
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