[OSM-dev] Zeroing or Extending a Hillshade-Tiff

Jochen Topf jochen at remote.org
Wed Mar 13 16:13:45 UTC 2013

On Tue, Mar 12, 2013 at 07:00:25PM +0100, Peter Körner wrote:
> Am 11.03.2013 21:10, schrieb Sven Geggus:
> >Peter Körner <osm-lists at mazdermind.de> wrote:
> >
> >>what way would you choose and wich tools could be used to go that way?
> >
> >Use the Water-Polygons from openstreetmapdata.com instead of land
> >polygons.
> That's not that easy for the polar regions, because transforming the
> splittet polygons to the destination projection results in gaps
> because of straigt lines not beeing curved.
> For the land there are complete polygons which are used on the
> Antarctica map but there are no complete water polygons, because
> they would be too complex (a huge polygon with 400.000+ holes).
> So in order to get this right one would need to modify jochend
> osmcoastline tool to support EPSG:3031 natively, to all corrdinates
> are transformed before splitting and calculating the water polygons.

Another option would be to split up the long straight lines resulting from
the splitting into shorter pieces. If the pieces are short enough, it should
be okay. Maybe there is some tool around that can do that easily? I don't
want to put more and more of these things into OSMCoastline, because they
are not really related to coastlines, but general issues with large objects.

My first plan was to have a separate tool for the splitting, but because
I needed the split land polygons to create the water polygons I decided
to add this functionality into OSMCoastline to make it not too complicated
to use for the most common cases.

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

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