Hi all,

my observations at resolution 22:
I think the patch re-introduces rendering problems at T-shaped crossings, 
sometimes they look like t-shapes at lower resolutions.
Sample: https://www.openstreetmap.org/node/260418111

It seems to filter more small polygons, even with  --min-size-polygon=0.
I think it tends to make polygons smaller, not sure why.

It sometimes reduces wrong zig-zagging, but only for ways with many points. In 
cities, where roads are often split into many small parts it sometimes makes 
things worse.

It probably helps for the special case contour lines and therefore I suggest to 
limit it to them.

Maybe the code to find the best place for a rounded coord should also consider 
to remove the point if that would give the best result.

Gerd

________________________________________
Von: mkgmap-dev <[email protected]> im Auftrag von Gerd 
Petermann <[email protected]>
Gesendet: Mittwoch, 28. April 2021 15:21
An: Development list for mkgmap
Betreff: Re: [mkgmap-dev] mkgmap-dev Digest, Vol 153, Issue 40 Resolution 23 
raster problems

Hi Felix,

I expect (more) small missing parts of complex shapes like forests or waterway 
areas (those without mkgmap:skipSizeFilter=true) and more obvious differences 
between shapes and lines, e.g. if a style renders outlines of buildings.

The maps are very different at res 22, so it is hard to say if there are more  
improvements then worsenings.

I've experimented with different orders of filters in the past. It's difficult 
to test because the changes heavily depend on the Styte AND the mapped objects 
AND the mappers preferences. For example, if landuse areas are glued to 
highways or not, if landuse areas are glued to other landuse areas or if there 
nodes are just very close.

Gerd

________________________________________
Von: mkgmap-dev <[email protected]> im Auftrag von Felix 
Hartmann <[email protected]>
Gesendet: Mittwoch, 28. April 2021 14:58
An: Development list for mkgmap
Betreff: Re: [mkgmap-dev] mkgmap-dev Digest, Vol 153, Issue 40 Resolution 23 
raster problems

Oh I thought it was mainly meant for contourlines. Did not know you intend it 
to be used in general. I am not really sure how and where to check for quality.

On Wed, 28 Apr 2021 at 20:13, Gerd Petermann 
<[email protected]<mailto:[email protected]>> wrote:
Hi Felix,

your screen shots only show contour lines but the patch works on all types of 
lines and polygons. So, please also check the results with other maps.

Gerd

________________________________________
Von: mkgmap-dev 
<[email protected]<mailto:[email protected]>>
 im Auftrag von Felix Hartmann 
<[email protected]<mailto:[email protected]>>
Gesendet: Mittwoch, 28. April 2021 04:54
An: Development list for mkgmap; Andrzej Popowski
Betreff: Re: [mkgmap-dev] mkgmap-dev Digest, Vol 153, Issue 40 Resolution 23 
raster problems

forgot 1.3 value - that is good enough (and this location is not the most 
difficult, but there are very few places that are worse. So I feel it's good 
enough as if it's fine here - there are very very few other places that are 
still problematic.


On Wed, 28 Apr 2021 at 10:50, Felix Hartmann 
<[email protected]<mailto:[email protected]><mailto:[email protected]<mailto:[email protected]>>>
 wrote:
Thanks for that patch, the improvement is not as big as from the previous patch 
- but there is some.
I analysed it a bit more - and I think there needs to be one more change - 
actually in general and not only for contourlines.

We need different values for the douglas peucker algorithm depending on 
resolution!

Right now we can only set one value, and that is multiplied for each resolution?
Based on the current state I would like to have

resolution
24= 0.0 or maybe actually have it active at 24 as well trying a value of 0.3 or 
so. Where there any problems with autorouting or why is it not possible to use 
it at resolution 24 as well?
23=1.3
22=2.6
21=3.9
20-11=5.4


Especially if we produce a map without resolution 24, then resolution 23 needs 
to have much lower DP value than the subsequent resolutions. Using 1.3 for 
resolution 23 makes the quality IMHO good enough to be used for an contourlines 
only map for GPS devices and skipping resolution 24 altogether. For Desktop use 
resolution 24 may still make sense for contourlines - but even then the 
difference is only in very steep areas.

Attached some screenshots at resolution 24, and at 23 with different DP values 
and one of patch2.

On Tue, 27 Apr 2021 at 23:16, Andrzej Popowski 
<[email protected]<mailto:[email protected]><mailto:[email protected]<mailto:[email protected]>>>
 wrote:
Hi,

some more experiments, see attached patch. I have tried to optimize
rounding of coordinates for lowest distance to line. This is not good
for polygons, because can creates gaps between adjacent polygons.

--
Best regards,
Andrzej
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--
Felix Hartman - Openmtbmap.org & VeloMap.org



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

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

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