[mkgmap-dev] [PATCH v5] sea polygons

Wed Aug 26 13:25:15 BST 2009

Christian Gawron escribió:
> This version of the patch fixes a bug in the previous version which
> caused tiles with no shoreline to be "flooded".
>
> Other improvements are
> - Shorelines are clipped at the boundary prior to the processing (may
> fix some problems related to input data)
> - Somewhat improved handling of non-closed shoreline segments (s. below)
>
> The main remaining problems are:
> - Flooded islands (problem in MultiPolygonRelation?)
> - Handling of non-closed shoreline segments not ending at the map
> boundary, usually a result of cutting the shoreline with osmosis
>  (e.g. country-extracts from geofabrik)
>  There are two possibilities to solve this problem:
>   1. Close the way and treat it as an island. This is sometimes the
> best solution (Germany: Usedom at the border to Poland)   2. Create a
> "sea sector" only for this shoreline segment. In some cases this seems
> to be the best solution
>       (see German border to the Netherlands where the shoreline
> continues in the Netherlands)
>   The first choice may lead to "flooded" areas, the second may lead to
> "triangles". Right now, the first choice is used for "nearly closed"
> segments.
I have generated a map for Canary Islands and it seems OK except one of
the islands that is flooded when I zoom in to "3 km level" in MapSource.
You can get the map at
http://mapas.alternativaslibres.es/MapSource_Canarias.zip (the
problematic island is the small one in the top right corner).
Cheers
Carlos