[mkgmap-dev] Multipolygon problem

Mon Feb 28 12:53:50 GMT 2011

2011/2/27 Martin Simon <grenzdebil at gmail.com>:
> Hi!
>
> This sounds like exactly the thing needed, as I create these Polygons
> seperately. :-)
>
> I tried to build the patched mkgmap from source but this failed. But
> as the patch is committed now, I'll simply try with the next
> automatically buit version from the website.

OK, I was wrong; I now tried to build a map with contour lines
generated by GroundTruth (commands: "GroundTruth.exe contours
--gridlat=1 --gridlon=1 -b=50,6,51,7 -o=50-6.ibf" and "GroundTruth.exe
ibf2osm -i=50-6.ibf").
Then I built a map from the resulting .osm file with a mkgmap style
just for polygons. The Lines were closed, but unfortunately, not
around the corners of the source file (the contour lines' start and
end points are exactly at 50/51 degree latitude and 6/7 degree
longitude).

GroundTruth doesn't add "bounds" to the osm file, but adding it
manually doesn't change the result.

As the contour lines generated by Groundtruth are always running
clockwise around a hill, what needed to be done is closing them from a
lines' endpoint clockwise around the tile edges until the startpoint
is reached *or* the startpoint of another contour line with the same
tags is reached, merging them, and continue.

I don't know at all how much work would need to done to implement this
behaviour...

--Martin