[mkgmap-dev] Analysis of MP issues in Finland

Fri Jan 29 21:15:55 GMT 2010

> It would be great if we could print a message saying "outer polygon does
> not contain one or more inner polygons; should some outer and inner roles
> be swapped?"

Yep, I just have to think about how to code that. The idea to check if 
an outer polygon does not contain any inner polygon is a good starting 
point (sounds very simple but simple is good :-). Additionally I could 
check if the outer polygon is contained by an inner polygon that is not 
contained by an outer polgon. So we can swap the rule and say: Check all 
inner polygons that are not contained by an outer polygon and complain 
about that. Sounds good and too difficult to implement :-)

>
> By the way, should we complain if there appear to be multiple outer polygons?
> I know that the outer polygon can consist of multiple role=outer lines
> (such as long coastlines split to 500 nodes each), but can there legitimately
> be multiple outer polygons?  Hmm yes, thinking about administrative borders,
> such as Russia+Kaliningrad (Königsberg), Denmark+Greenland, or from the past
> West Germany + West Berlin.

It is defined in the description of the multipolygon relation 
(http://wiki.openstreetmap.org/wiki/Relation:multipolygon) that multiple 
outer polygons are allowed. And from my point of view it doesn't harm 
anything.

WanMil