[mkgmap-dev] sea rendering, geonames

Mon Jan 30 16:54:34 GMT 2012

Thanks Thorsten, I'll try the geonames/description next time.

The reason of the flooding is a bit complicated.
Inspection of the problematic tile turned out that the flooding was not caused by a broken coastline, but some kind of problem with rendering of the land-polygon.
It looked flooded but that was because I used "sea" blue as background colour (0x4b) and green for land, because in some parts of the sea there were no sea tiles at all
and in Mapsource they get the default grey background:

http://img814.imageshack.us/img814/9278/nosea.jpg

With this particular tile near Ipswich the splitter returns an "Area too small to split" error at http://www.openstreetmap.org/?lat=51.87639&lon=1.24321&zoom=17

Maybe this is the cause that it doesn't get a land background, it only gets the default 0x4b background (which was blue in my case). If I make the 0x4b grey again it looks like this screenshot:

http://img685.imageshack.us/img685/2331/ipswich.jpg

Also note the upper right corner of the sea, it is filled with land, despite of the fact that I turned off the floodblocker.
This area contains some ferry lines, marine borders and a windmill park: http://www.openstreetmap.org/browse/way/113741007

So I still keep two problems with the generate-sea option: multipolygon, extend-sea-sectors,land-tag=natural=background

A) the sea is not totally filled with polygons and has some gaps. Those gaps can be filled with a blue 0x4b background as workaround.
B) sometimes there is a tile generated in the sea without coastline but then the whole tile is turned into land.

I tried a different option for generate-sea: polygons,extend-sea-sectors,close-gaps=6000,land-tag=natural=background

Land in the problematic tile around Ipswich is now land again (green), sea is empty, 0x4b (which can be blue if I use that colour). I still have a land tile in the North Sea. As workaround I can delete that tile, then it will be an empty tile with 0x4b background but then I loose the objects in this tile.