[mkgmap-dev] [PATCH v2] - handle "anti-islands"

Thu Jan 28 08:29:49 GMT 2010

Hi Mark,

> > > Can you please check to see whether this location is situated very
> > > close to the corner of a tile? I am guessing that the coastline cuts
> > > the corner of a tile and so you end up with nodes on each of the tile's
> > > edges at the corner.
> > 
> > Like I wrote in the message you replied to, it is at the tile border,
> > lat=62.226562.  If you go to the browse URL, the marker is very slightly
> > SSW of a node of http://www.openstreetmap.org/browse/way/23553585
> > (the coastline).  I would guess that this is some rounding issue.
> > Initially, mkgmap thinks that the pre-existing node is not at the tile
> > border and adds a node there, and later it notices that the coordinates
> > are equal after all.
> 
> Yeah, I know it's on the border but is it at a tile corner?

Sorry, no, it is not.  The tile corners are more than 100 km to the west
and east.

> The patch I posted does (read should) fix a bug in the sea code because
> when it's making up the edges of the land mass that is clipped at the
> tile's edge it doesn't notice if the coastline reaches the tile
> edge  exactly at a corner of the tile. In that (albeit unlikely) case,
> the existing code would generate a consecutive point and you would get
> a message like the above.

I did not look at the map output yet.  So far, I haven't enabled
generate-sea in my "release" maps, because last time I checked, the
output was unusable due to flooding.  I am planning to enable it near term.

	Marko