[mkgmap-dev] Flooding in Germany

Wed Jan 20 10:55:25 GMT 2010

On 20.01.2010 11:12, Clinton Gladstone wrote:
> 2010/1/20 Felix Hartmann <extremecarver at googlemail.com 
> <mailto:extremecarver at googlemail.com>>
>
>
>     Just downloaded new data for Germany, problem persists:
>
>     Is this maybe not solvable with current code?
>     I'll retry with different max-nodes to see if it then maybe works.
>
>
> I also noticed this with the Geofabrik extract of Germany: The tile 
> around Bremen always gets flooded. My tiles are different from yours, 
> so I assume we have different max-nodes parameters.
>
> I did also compile Geofabrik's complete Europe extract: here the 
> problem did not occur. There were a couple of other landlocked tiles 
> in France and Poland which were flooded though (caused by, I assume, 
> some bad data in the tiles).
>
> This may mean, therefore, that the problem stems from the way 
> Geofabrik extracts Germany. You could try making your own extract 
> (using a bounding box) for Germany out of the Europe extract. Perhaps 
> this would work better.
>
> Cheers.
-- I reduced maxnodes to 800.000 and then the flooding became a lot 
smaller (and not the whole tile anymore). The problem seems to be that 
there is sea in the North, then a section with land until the boarder, 
and then further south again sea.
See below (or to the right) a screenshot of Garmin (Mapsource) Topo 
Deutschland v2. One can nicely see the problem of the country boundary 
going seperated through the sea. It is really strange that there is a 
sea section without exit on dutch territory. But well.

I don't know whether this can be fixable in code, or whether we should 
simply take it out from the main ocean and make a separate sea section 
in OSM data to make it easier to work with country extracts.

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