[mkgmap-dev] Splitting an country borders?

Sat Sep 19 10:12:42 BST 2009

>  
>   
>> I seem to remember someone mentioning that Garmin supports non-rectangular
>> map tiles.  Would that help?  Or would it be too much effort with too little
>> gain to implement that in mkgmap (and splitter)?
>>     
>
> I have seen a Garmin map with boundary points that do not lie on a
> rectangle so, it's plausible that the boundary between two tiles can be
> any shape. The important thing is that the coordinates of the boundary
> points have to be the same in both tiles so that the GPS can match them
> up.
>
> In principle, it should be quite possible to route across tiles that
> have a wiggly boundary. This could be achieved quite straightforwardly
> by the splitter tagging the boundary points so that mkgmap knows where
> they are.
>
>   
Yes, the official garmin maps have a not ractangular boundary and 
routing works perfect. So it is possible.

The problem seems to be the osmosis data from geofebtric. They dont cut 
a line at the boundary and create a new node exact on the boundary, but 
instead simply drop the last segement, which crosses the border.
If you try to merge two parts from geofabric, e.g. austria and germany, 
then all segments crossing the borderline are missing. (At least this 
was the case last time I tried it an year ago. There was an other thread 
on the list discussing this).

So imho it would be an better idea to fix the osmosis sources than 
implement it to splitter.