On Mon, Jun 06, 2011 at 03:59:28PM +0100, Adrian wrote:
I inspected the coastline data of this tile in JOSM and I could not see any problem with it.
Did you invoke the JOSM Validator on it? The coastline checks are (or at least used to be) in the INFO level; you may have to crank up the chattiness. Note that JOSM and mkgmap do not detect the same class of coastline errors; there is some overlap. Last time I had to use my brain a little was when mkgmap emitted a warning but JOSM Validator thought it is fine. If I remember correctly, the problem was that the map data contained two clockwise (or counter-clockwise) natural=coastline ways so that they did not intersect, but one way fully enclosed the other. I would be surprised if mkgmap did not emit some coastline warnings for the map data. It is sometimes a bit challenging to decipher the messages and it might be impractical to keep the data tidy at all times. In Finland, coastline bugs occur rarely, maybe a few bugs once in a couple of weeks. I only use extend-sea-sectors for one tile, as a work-around because the coastline in the finland.osm.pbf in the north (Tornio/Haparanda) does not extend to as far west as my tile would like to have it. Before going PBF, I had a sed or perl filter that moved the coastline endpoint to the west in the XML data. Best regards, Marko