[mkgmap-dev] Option generate-sea buggy

Mon Oct 18 08:33:31 BST 2010

On Sun, Oct 17, 2010 at 09:17:33PM +0200, Minko wrote:
>Maybe it's caused by the geofabrik extract of germany.osm because I 
>notice the same problems happen for the same region (near Emden) if I 
>use the Benelux abstract from planet.openstreetmap.nl
>For my Benelux maps I have use the europe.osm extract from geofabrik 
>and then split it with a wider border area.

My workaround for this problem is to move the endpoints of the coastline 
to the tile borders. This is part of my osm2img.sh script:

bzip2 -dc "$OSM_BZ2"|
perl -e \
'my $del=0;
while(<>){
     $del=1 if (/<relation.* version="1".* user="usm78-gis"/);
     s/(<node id="28954644".*lat=)"60\.51564"/$1"59.326172"/;
     s/(<node id="29193143".*lon=)"24\.12826"/$1"19.072266"/;
     print unless $del;
     $del=0 if m|</relation>|;
}'|
tee "$OSM"|
$JAVACMD $JAVACMD_OPTIONS -jar splitter.jar --split-file=areas.list

>Maybe the German extract has a border area that is too small so some 
>coastlines get broken?

That should be easy to check. Just extract the natural=coastline ways 
from the German extract with Osmosis, and load the result in JOSM. That 
is how I fixed the generate-sea for my map of Finland. Something like 
this should do the trick:

osmosis --rx germany.osm --tf accept-ways natural=coastline --used-node --wx germany-coastline.osm

	Marko