[OSM-dev] Coastline changes Antarctica

Jochen Topf jochen at remote.org
Mon Mar 18 16:02:00 UTC 2013


On Tue, Mar 12, 2013 at 10:09:30AM +0100, Jochen Topf wrote:
> On Tue, Mar 12, 2013 at 01:53:30AM -0700, Paul Norman wrote:
> > You should not import the -180/180 part until a plan for tile.osm.org has
> > been worked out.
> 
> If this isn't solved before we do the import we just add those bogus coastline
> ways back in as a temporary measure.

Christoph did the import on the weekend. The bogus coastline is not in there.
If somebody still needs it, he can add it back in.

These maps already have all the current data and mostly current tiles:
 http://www.openstreetmap.de/karte.html
 http://polar.openstreetmap.de/antarctica
  
Current coastlines are available from:
 http://openstreetmapdata.com/

You probably want for z10+:
 http://data.openstreetmapdata.com/land-polygons-split-3857.zip
 (thats the replacement for processed_p)

and for z0-9:
 http://data.openstreetmapdata.com/simplified-land-polygons-complete-3857.zip
 (thats the replacement for shoreline_300)

If you want to do this yourself, they are generated with:
 osmcoastline -o coastlines-split-3857.db --no-index --srs=3857 --max-points=1000 --bbox-overlap=50 --output-lines --output-polygons=both coastlines-current.osm.pbf
 ogr2ogr -f "ESRI Shapefile" land-polygons-split-3857 coastlines-split-3857.db land_polygons

and:
 osmcoastline -o coastlines-complete-3857.db --no-index --srs=3857 --max-points=0 --bbox-overlap=0 coastlines-current.osm.pbf
 spatialite -batch -bail -echo coastlines-complete-3857.db <simplify.sql
 ogr2ogr -f "ESRI Shapefile" simplified-land-polygons-complete-3857 coastlines-complete-3857.db simplified_land_polygons

Instead of the simplified polygons you can also use the complete polygons,
but they are 10 times as large and in the low zoom levels you will not see
much difference. The split polygons will probably not work for small zoom
levels because you will see the seams between polygons. This could be solved
by using larger overlaps or by using the "gamma" parameter when rendering,
but it is probably easiest just to use the new simplified polygons because
you don't have to change anything in your Mapnik config. We'll probably need
some experimentation to see which configuration is best in the long run.

Jochen
-- 
Jochen Topf  jochen at remote.org  http://www.remote.org/jochen/  +49-721-388298



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