[mkgmap-dev] Duplicate roads added by default style

Mon May 10 16:15:53 BST 2021

Hi Gerd, 

I misunderstood the problem you were discussing - I was indeed referring to
overlapping ways from different OSM ways. The multiple ways from the same
OSM way is not a problem for me in the style I use (I think - I haven't
enabled any logging of this so perhaps might not have noticed).

Overlapping ways from different OSM ways is however a problem I have. Mainly
because I include routing around car parks and some car parks have part of
their outline coincident with a road.

Cheers,
Mike
-----Original Message-----
From: Gerd Petermann [mailto:gpetermann_muenchen at hotmail.com] 
Sent: 10 May 2021 16:07
To: Development list for mkgmap <mkgmap-dev at lists.mkgmap.org.uk>
Subject: Re: [mkgmap-dev] Duplicate roads added by default style

Hi Mike,

Please give an example, I don't understand what you mean. Do you talk about
the situation that two OSM ways are overlapping (sharing segments)? That
would be a completely different problem and requires a different check which
maybe also looks at the layer=* tag.

The issue here is that the style adds multiple identical routable lines for
the same OSM way. Those duplicates would just blows up the road network and
therefore can be safely ignored.

The attached patch is like v5 but contains the additional check in
StyledConverter.

Gerd

________________________________________
Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von Mike
Baggaley <mike at tvage.co.uk>
Gesendet: Montag, 10. Mai 2021 16:56
An: 'Development list for mkgmap'
Betreff: Re: [mkgmap-dev] Duplicate roads added by default style

HI Gerd,

I would ideally like a new mkgmap tag that if found would remove the
duplicated way or part of a way. This could get tricky when the part to be
deleted is in the middle of the way, as it would need to produce two ways.
Something like:

railway=platform {set mkgmap:removeoverlap=true} [0x16 road_class=0
road_speed=0 resolution 23]

The code would need to check that the access of the overlapping way and
could merge the accesses if necessary. A decision would also have to be made
what to do if two overlapping ways both have the tag set.

Cheers,
Mike

-----Original Message-----
From: Gerd Petermann [mailto:gpetermann_muenchen at hotmail.com]
Sent: 10 May 2021 10:21
To: Development list for mkgmap <mkgmap-dev at lists.mkgmap.org.uk>
Subject: Re: [mkgmap-dev] Duplicate roads added by default style

Hi Felix,

sure, I meant roads which RoadMerger would combine. Roadmerger checks a lot
more attributes.
Multiple (different) routable ways for one OSM way are quite normal, esp.
with the --make-opposite-cycleways option.

I think it's worth to log a warning for each.

Gerd

________________________________________
Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk> im Auftrag von
Felix Hartmann <extremecarver at gmail.com>
Gesendet: Montag, 10. Mai 2021 11:16
An: Development list for mkgmap
Betreff: Re: [mkgmap-dev] Duplicate roads added by default style

It makes the style very complicated to try to remove any identical copies -
I do this by setting loads of temporary keys, that are checked later for
existing or not existing and based on that add or not add other lines.  I
guess some actual duplicates will still happen.

On Mon, 10 May 2021 at 17:14, Felix Hartmann
<extremecarver at gmail.com<mailto:extremecarver at gmail.com>> wrote:
hmm no, please no warning. This can be very beneficial. As long as the type
OR road_speed OR road_class OR oneway plus direction is different. The above
of course makes no sense, as it will set exactly the same road twice.

On Mon, 10 May 2021 at 16:49, Gerd Petermann
<GPetermann_muenchen at hotmail.com<mailto:GPetermann_muenchen at hotmail.com>>
wrote:
Hi all,

while double checking patch for the RoadMerger I wondered what might happen
if the style adds two or more identical roads for the same OSM way.
Of course this makes no sense but to my surprise I found out that this
really happens with the default style.
A way with e.g. highway=footway and railway=platform is added twice
...
highway=footway {set tmp:stopMopUp=yes} [0x16 road_class=0 road_speed=0
resolution 23 continue with_actions]
...
railway=platform [0x16 road_class=0 road_speed=0 resolution 23]

Of course the default style should be fixed to avoid that but I think mkgmap
can detect this easily and should print a warning when the style does that?

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

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

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