[OSM-dev] Super-relations or not

Peter Budny peterb at gatech.edu
Mon Nov 1 16:25:19 GMT 2010


Marcus Wolschon <Marcus at Wolschon.biz> writes:

> I'm using routes in way-simplification to generate simplified maps for
> realtime rendering of larger areas when zooming out.
>
> It's quite a lot of work with LOTS of cases to try to sort
> route-relations that are randomly sorted with parts
> being other relations instead of ways, parts being contained twice,
> parts missing in the relation but having a
> ref= -tag or a ref_nat= -tag or ... , parts having a ref= -tag with
> the wrong road-number that should NOT be
> made a part of this simplified way,...

In fairness, much of that sounds like errors.  A route relation ought to
contain exactly the things that are part of it, no more no less.  The
ref=* tag on ways is irrelevant for a route relation.

What would you prefer to see the structure of the relation be, given
your druthers?  Should both directions of a road be in one relation,
tagged with roles?  Should a oneway=no way have a role?  Should it be in
the relation twice with different roles?  Should there be separate
relations for each direction with a super-relation to hold them both?
If super-relations are used, does it still make sense to use
forward/backward tags as appropriate?


As far as I'm concerned, the difference in what's required to tag things
is minimal between these concerns.  Therefore, wouldn't it make the most
sense to choose whichever is programmatically the easiest and most
flexible to deal with?
-- 
Peter Budny  \
Georgia Tech  \
CS PhD student \



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