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[mkgmap-dev] Routable intersecting polylines not corrected and some other bugs

From Felix Hartmann extremecarver at gmail.com on Tue Dec 7 22:05:17 GMT 2010

I just used the verify maps function of gpsmapedit (a new version was 
released a few days ago, that improved the error checking possibilities 
-- http://www.geopainting.com/en/ ) to check for errors in mkgmap 
created maps. Most found stuff is IMHO not really important.

However there should never be the case that a routable line intersects 
Of course this is a data fault in OSM, but maybe such intersecting lines 
harm the routing over longer distances...

Usually the reported problems are roundabouts (but not tagged as such) - 
and no problem, sometimes there are really strange shapes however, or 
obvious errors like this (note the oneway arrows, that go against each 

There are also sometimes real intersections without roundabouts - those 
are really really rare however (found one, but then gpsmapedit crashed 
before I could make a screenshot, would need to search again to find em).

Also sometimes gpsmapedit complains about too short distance (under 
2.3m) of routing nodes, but I think these are false positives, as I 
think this problem got fixed after a report by me about 1 1/2 years ago.

Not sure what to make of the other errors found. I think most are not 
really harmful - but just to list them.
Other bugs that should be fixed but are not high importance to what I 
would guess:
-- No space at the end of a string. (pretty rare)
-- Polygons intersect themselves (again error in osm data, but cutting 
intersecting polygons into seperate single ones would be cleaner - or 
drop them altogether as obviously data is wrong) - this is quite common.
--- Polygons have jitter - Polygons that have parts that get averaged to 
a straight line or that are a strait line in OSM data. Obviously those 
jitter points should be dropped.

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