[mkgmap-dev] Suppressing or fixing zero-length arc warnings

Sat Sep 26 19:35:59 BST 2009

I have fixed some zero length arc warnings in the Finland extract.  The
count has gone down from 334 to 289.  Most warnings are now for unnamed
roads.  Some of them are badly mapped cycleways or footways, but some are
genuine zero-length arcs that I think should be silently dropped or merged
by mkgmap.

There are some cases that I am having trouble with:

(1) steps and short ramps or paths around them, e.g.,

http://www.openstreetmap.org/browse/way/31345355
at
http://www.openstreetmap.org/?lat=60.15495&lon=24.86515&zoom=17

Perhaps mkgmap should merge the highway=steps to highway=footway?
Could this be done at the style-file level somehow?

(2) short highways that end at some region boundary, such as this one:
http://www.openstreetmap.org/browse/way/31359067
http://www.openstreetmap.org/?lat=60.15515&lon=24.88084&zoom=17

Could we introduce a tag for short arcs, similar to noname=*?  It could
be in the mkgmap namespace and renamed by a style file.  For example, to
suppress warnings about short steps, just add a rule like this:

highway=steps { add mkgmap:zerolength=yes }

(3) crossings on narrow city streets where the footway has been split into
tiny segments due to a tram line crossing:

http://www.openstreetmap.org/browse/way/28842855
http://www.openstreetmap.org/?lat=60.16600&lon=24.94182&zoom=17

See the Bulevardi/Yrjönkatu crossing.  What to do about this?  The same
work-around as above?

	Marko