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.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@lists.mkgmap.org.uk> im Auftrag
> von Pinns UK <osm@pinns.co.uk>
> Gesendet: Montag, 4. November 2019 16:29
> An: mkgmap-dev@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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