[mkgmap-dev] documentation of new option in branch

Tue Nov 5 10:12:36 GMT 2019

Hi Gerd

Looks good, but should add, after "island as a start", " or end".
Also fix "metres" to "meters" 

Ticker

On Tue, 2019-11-05 at 09:18 +0000, Gerd Petermann wrote:
> Hi all,
> 
> thanks for all the input. Here is my 2nd try:
> --check-routing-island-len=INTEGER
>         Routing islands are small road networks which are not
> connected to other
>         roads. A typical case is a footway that is not connected to
> the main
>         road network, or a small set of ways on the inner courtyard
> of a large
>         building
>         These islands can cause problems if you try to calculate a
> route and the GPS
>         selects a point on the island as a start. It will fail to
> calculate the
>         route even if a major road is only a few steps away. If this
> option is
>         specified, then mkgmap will detect these islands. If the
> value is set to
>         zero, mkgmap will simply report the islands (you will need to
> set
>         uk.me.parabola.imgfmt.app.net.RoadNetwork.level=INFO to
> activate logging of
>         the message). If the value is greater than zero, mkgmap will
> mark islands
>         with a total length less than the specified value in metres
> as not routable.
>         Reasonable values are 500 or higher.
>         The default is for the check to not take place.
>         If any of the roads forming the island touches a tile
> boundary or
>         a country border the island is ignored, as it may be
> connected to other
>         roads in a different tile.
>         See also option --add-boundary-nodes-at-admin-boundaries.
> 
> 
> As Arndt has pointed out there is a possible problem with the island
> detection when the input file doesn't cover the tile boundary.
> This is quite normal. When you split eg. germany-latest.osm.pbf
> you'll get lots of tiles at the country boundary. Since Geofabrik
> uses simplified polygons you will see many small islands next to the
> cutting polygon. These islands may be connected to the road network
> in the neighbour country without touching the country border.
> Of course this is also the case when you use a polygon in splitter
> (options --polygon-file or --polygon-desc-file).
> So, I would not use this test for OSM quality checks (geofabric
> provides this in the routing view of OSM inspector).
> 
> Gerd
> 
> ________________________________________
> Von: Gerd Petermann <gpetermann_muenchen at hotmail.com>
> Gesendet: Montag, 4. November 2019 18:17
> An: Felix Hartmann
> Betreff: AW: [mkgmap-dev] documentation of new option in branch
> 
> Hi Felix,
> 
> the number is about the total length of the roads in the island,
> measured in meters.
> 
> Gerd
> 
> 
> ________________________________________
> Von: Felix Hartmann <extremecarver at gmail.com>
> Gesendet: Montag, 4. November 2019 17:51
> An: Gerd Petermann
> Betreff: Re: [mkgmap-dev] documentation of new option in branch
> 
> Ah okay - so it should be explained that the Integer is the number of
> roads which form an island. e.g. 100 so anything below 200 100
> segments is still an island and thereby routing disabled.
> That is quite interesting then and an addition (still
> set_unconnected_type=XXXXX is then pretty obsolete if its only about
> making the road unroutable).
> 
> On Mon, 4 Nov 2019 at 17:40, Gerd Petermann <
> gpetermann_muenchen at hotmail.com<mailto:
> gpetermann_muenchen at hotmail.com>> wrote:
> Hi Felix,
> 
> mkgmap:set_unconnected_type works very different.
> 1) It only detects single roads not connected to other roads, the
> island detection also finds multiple roads which are only connected
> to each other
> 2) the island detection adds the line as a road to NET, it just
> doesn't add it to NOD. So address search works as usual.
> (I am not yet 100% sure if this is a good idea, have to do more
> testing here)
> 
> Island detection happens after processing of
> mkgmap:set_unconnected_type, right before the AngleChecker is called.
> 
> Gerd
> 
> ________________________________________
> Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk<mailto:
> mkgmap-dev-bounces at lists.mkgmap.org.uk>> im Auftrag von Felix
> Hartmann <extremecarver at gmail.com<mailto:extremecarver at gmail.com>>
> Gesendet: Montag, 4. November 2019 17:27
> An: Development list for mkgmap
> Betreff: Re: [mkgmap-dev] documentation of new option in branch
> 
> Hi
> So basically this is a global:
> 
> set mkgmap:set_unconnected_type=none;
> 
> Or is there a difference? I've used the unconnected_type and
> semi_connected type basically for all routable lines in my style
> -file. The unconnected_type is now obsolete if you just used to
> disable routing by setting an unroutable type - correct?
> 
> Have you tested that the global option is run after
> semi_connected_type and unconnected_type? Because first the style
> should be able to remove them or change them to unroutable type -
> then leftover islands should be covered with this method.
> 
> 
> 
> Felix
> 
> 
> On Mon, 4 Nov 2019 at 17:06, Ticker Berkin <rwb-mkgmap at jagit.co.uk<ma
> ilto:rwb-mkgmap at jagit.co.uk><mailto:rwb-mkgmap at jagit.co.uk<mailto:
> rwb-mkgmap at jagit.co.uk>>> wrote:
> Hi
> 
> I think the default should be either:
>   Don't check for routing islands
> or:
>   Check for and remove islands of any length
> but I don't feel that strongly about this aspect.
> 
> In the documentation, it should mention the effect of a road meeting
> a
> tile boundary or boundary nodes added at admin boundaries.
> 
> I've been using this feature for a couple of weeks now and it has
> stopped a lot of "Route Calculation Error"s - Thanks Gerd.
> 
> Ticker
> 
> On Mon, 2019-11-04 at 15:37 +0000, Gerd Petermann wrote:
> > Hi Nick,
> > 
> > as always the information is written with the logger (1). You have
> > to
> > activate logging at info level with
> > uk.me.parabola.imgfmt.app.net<http://uk.me.parabola.imgfmt.app.net>
> > <http://uk.me.parabola.imgfmt.app.net>.RoadNetwork.level=INFO
> > 
> > (1) 
> > https://wiki.openstreetmap.org/wiki/Mkgmap/dev#Enabling_Debugging
> > 
> > Using a negative value for NUM means that mkgmap doesn't calculate
> > the islands at all, using
> > 0 means that it only reports the islands. If you want to remove
> > islands you can start with a value like
> > 500. The default is 0.
> > 
> > Gerd
> > 
> > ________________________________________
> > Von: mkgmap-dev <mkgmap-dev-bounces at lists.mkgmap.org.uk<mailto:
> > mkgmap-dev-bounces at lists.mkgmap.org.uk><mailto:
> > mkgmap-dev-bounces at lists.mkgmap.org.uk<mailto:
> > mkgmap-dev-bounces at lists.mkgmap.org.uk>>> im Auftrag
> > von Pinns UK <osm at pinns.co.uk<mailto:osm at pinns.co.uk><mailto:
> > osm at pinns.co.uk<mailto:osm at pinns.co.uk>>>
> > Gesendet: Montag, 4. November 2019 16:29
> > An: mkgmap-dev at lists.mkgmap.org.uk<mailto:
> > mkgmap-dev at lists.mkgmap.org.uk><mailto:
> > mkgmap-dev at lists.mkgmap.org.uk<mailto:
> > mkgmap-dev at lists.mkgmap.org.uk>>
> > Betreff: Re: [mkgmap-dev] documentation of new option in branch
> > 
> > Hi Gerd
> > 
> > Thanks for all you work with regards routing islands!
> > 
> > a) Is there a way of finding out how many .if any. routing islands
> > were found given a certain length?
> > 
> > b)  if NUM is negative is there any point in adding --check-routing
> > -island-len=NUM
> > 
> > Nick
> > 
> > 
> > 
> > On 04/11/2019 13:58, Gerd Petermann wrote:
> > 
> > Hi all,
> > 
> > I think the work on the branch is almost done.
> > Attached is a patch to add documentation for the new option.
> > Please help to improve it:
> > 
> > --check-routing-island-len=NUM
> >         Routing islands are small road networks which are not
> > connected to other
> >         roads. Typical case is a footway that is not connected to
> > the
> > main road
> >         network. These islands can cause problems if you try to
> > calculate a route
> >         and Garmin selects a point on the island as a start. It
> > will
> > fail to
> >         calulate the route even if a major road is only a few steps
> > away.
> >         When calculating the NOD data mkgmap detects the islands.
> > The
> > option
> >         --check-routing-island-len=NUM can be used to tell mkgmap
> > that islands with
> >         a total length below NUM meters should not be written to
> > NOD.
> > The effect is
> >         that the corresponding roads are visible as usual but they
> > are not
> >         routable.
> >         A negative value for NUM means that mkgmap skips the island
> > check.
> > 
> > ciao
> > Gerd
> > 
> > 
> > 
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> 
> --
> Felix Hartman - Openmtbmap.org & VeloMap.org
> Schusterbergweg 32/8
> 6020 Innsbruck
> Austria - Österreich
> 
> 
> --
> Felix Hartman - Openmtbmap.org & VeloMap.org
> Schusterbergweg 32/8
> 6020 Innsbruck
> Austria - Österreich
> _______________________________________________
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