[mkgmap-dev] Merging adjacent multipolygons

Fri Feb 26 09:03:28 GMT 2010

Hi WanMil,

> So in the end what does it mean? The artificial cut will be handled  
> as one segment of the outer polygon and will therefore be tagged with  
> the multipolygon tags. This is the same as happens with all inner  
> cuts by the mp code.

That is not a big deal with artificially split natural=water  
multipolygons, as the border lines of the lake will be the same colour  
as the lake. (And I do not think that there any other huge  
multipolygons than lakes.)

>  From my point of view as long as it isn't widely accepted by the  
> community mkgmap should not implement workarounds that help other  
> tools like Osmarender to work properly.

It is not just rendering tools, but editing tools and the OSM server. I  
tried to view the history of one of the multipolygons that I created,  
and the server timed out, repeatedly. OSM just does not scale if there  
are thousands of 500-node ways in a relation.

I guess this means that I will be relying on generate-sea in the  
future. If someone wants to create lake multipolygons for the remaining  
huge lakes in Finland (for example if they want to tag islands), that  
is up to them.

I have been considering "glueing" artificial natural=coastlines to  
"seal" the Geofabrik Finland extract, to avoid flooding with  
generate-sea. Do you have any suggestion how to do this efficiently?  
Optimally, splitter would input two files, my coastline-glue.osm and  
the finland.osm.bz2 from Geofabrik.

	Marko