[mkgmap-dev] State of the coastline art

Wed Mar 31 17:27:19 BST 2010

On Wed, Mar 31, 2010 at 12:30 AM, Marko Mäkelä <marko.makela at iki.fi> wrote:

> On Tue, Mar 30, 2010 at 11:08:40PM -0800, NopMap wrote:
> > - What level of confidence do you achieve with generate sea? Many posts
> > still mention minor failures, disappearing islands etc.
>
> As far as I am concerned, it just works.  Any errors will be logged and
> will
> come through my error message filter.  You can fetch my scripts and files
> at
> http://www.polkupyoraily.net/osm/ and adapt to your area.
>
>
can confirm that. now also --generate-sea=multipolygon works and didn't have
any failures on whole california which has some real complex coastlines.
don't remember the exact mkgmap version. any newer one will do.
I like it more this way because I don't need to have a typ file

> Also, when debugging coastline errors (gap in coastline, coastline not
> extending to map border), you may want to use a command like this:
>
> osmosis --rx finland.osm.bz2 --tf accept-ways natural=coastline --used-node
> \
> --wx finland-coastline.osm
>
>
xapi is your friend and can achieve the same without downloading the planet
or excerpts
wget
http://www.informationfreeway.org/api/0.6/way\[natural=coastline\]\[bbox=-124.5,32,-114,42\]-O
coastline.osm

> The resulting file should be so small that you can load it in JOSM
> to see the way and node ids of the broken coastlines.
>
> > - Is it possible to save the resulting sea/land polygons for later
> re-use?
> > Apparently the OSM data changes more frequently than the actual coastline
> > and re-generating it from scratch every time you update is not necessary.
>
> Generating the coastline is not that slow any more.  If you absolutely
> wanted,
> I guess you could generate a separate map layer with just the sea, and
> compile
> your regular map without --generate-sea.
>
>        Marko
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