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

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 
itself.
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 
other):

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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