[mkgmap-dev] [PATCH v5] sea polygons

Tue Aug 25 22:46:50 BST 2009

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.

Best wishes
Christian

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