[mkgmap-dev] trouble routing across extracts

Fri Jan 13 23:25:36 GMT 2012

This combinining-extracts approach used to work for me.  I used
cloudmade state extracts (back when they were updated regularly).  My
understanding was that the extracts had enough data beyond the
boundaries so that when neighboring extracts were fed to splitter one
ended up with connected ways.  Then, after a lull in map building, I
used geofabrik state extracts and found that I couldn't route across
state lines.

Certainly I can see that this won't work in general if there isn't a
node across the line in one or the other extracts so that the resulting
union of datasets isn't connected.  But if the union is connected, it
seems that routing should work.

(And, I believe that people have added near-state-line nodes in some
cases to make the state-union routing work.  My point is that even if
it's theoretically impossible for the scheme to be correct, it can work
well enough to be highly useful.)

My desire to use state extracts stems from wanting to update
massachusetts much more frequently than others -- or whatever states I'm
about to be in, but still build new england maps.   While I could use
us-northeast, that puts more load on Frederik's server, and there is no
solution for the region boundaries.

So are you saying  that the geofabrik extracts don't contain any nodes
across the borders?  Do the ways (that in fact cross the borders) then
stop short of the border?   How did this used to work with cloudmade
extracts?
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