Toby Speight schrieb:
I've just started using the --generate-sea option, and it almost works. The problem is that of the UK, the whole of northern Scotland (north of a line through Stirling) is inverted - i.e. the land is blue and the sea is light yellow (black at night). This is inconvenient, as that's where I live.
What's the likely cause? Could it be due to an island that's tagged in the wrong direction? I've checked the most northerly and most westerly islands and they all look okay to me. GeoFabrik's OSM Inspector doesn't flag up any coastline errors in that area, so that's no help.
Could you provide me a download link for the offending tile? Did mkgmap print a warning message "Non-closed coastline segment does not hit bounding box: ..."? The algorithm I implemented handles two cases of land masses: - closed shoreline segments (aka islands) - shoreline segments which are not closed but extend to the border of the tile (i.e. the intersection of a closed shoreline with the bounding box) In the latter case the shoreline is "closed" along the tile border. The algorithm then generates a sea background and a multipolygon relation which adds a "hole" for each landmass. Obviously a landmass with a non-closed boundary will be drowned by that approach :-) One limitation I know of arises with country extracts from geofabrik - they have shorelines cut-off at the country border. As UK is a big island, this should not be the cause of your problem, though. Best wishes Christian