[OSM-dev] Relationships - working prototype
Frederik Ramm
frederik at remote.org
Thu Aug 23 13:47:36 BST 2007
Hi all,
thank you for discussing & trying the relationship stuff in my
absence. I was happy to see that many people recognized the potential
of the concept.
I have noted that discussion has partly focused on turn restrictions,
with non-relationship ideas proposed by, among others, Andy Robinson
and Steve Coast. Both these suggestions would work (in a way - I
don't want to go into too much detail here). But finding some other
way to describe turn restrictions does not diminish the case for
relationships in general.
Someone has said that relationships would somehow impose a constraint
on what people can enter into the system and that this would be un-
OSM-ish. The opposite is the case; anything that was possible before
is still possible, and there is much more room for mapping creativity
- or "unexpected uses"! - with something like relationships in place.
I view the whole thing as an offer to the mapping community - if it
is not taken up, then it will die and eventually be removed with very
little harm done. In my eyes, there is very little risk involved with
just taking relationships on board and seeing how they're used. It is
not a giant change, really.
I would ask those who oppose the idea of relationships to rethink: If
you believe that relationships are unnecessary, the best way to prove
your point is to agree to their deployment and, when the next API
overhaul is due, just get agreement to drop them based on lack of
practical use. We do allow people to map all kinds of nonsense using
fantasy tags, and this is not an accident - we say this over and
over, OSM is where the mappers decide what to map, not the database
designers. This is almost an OSM "core value". Relationships will
furnish the mapper with a powerful new tool to map things that could
not be properly mapped before, and mappers can use this tool with all
the degrees of freedom they have applied to tagging in the past. If
mappers don't use it because other ideas are simpler, easier, faster,
nicer, or better supported by their editors - fine, they don't have to!
A lot of detailed changes have been suggested and I'll read
everything and try to make it into a "version 2 prototype" which I'll
announce here after the weekend. One thing I'm pretty sure of is that
we need a new name; I suggest we use "relation". ("relationship" or
"group" would also be ok for me, I don't really mind.) - This word
does not encompass all possible uses, as the object can also be used
to represent something by itself, but (a) it'll probably work in 90%
of cases, and (b) a community that routinely uses something called
"way" to describe a lake or forest should have no problem with a
little leeway concerning names ;-)
I would like to enlist your help for the following areas of this sub-
project:
(a) Is there anyone who is good enough at hacking one of our existig
renderers - Mapnik, Osmarender, or the Postscript renderer - to
actually modify one of them to support one or the other kind of
relationship, a "superway" perhaps? That would make a very cool proof
of concept.
(b) The same for routing - anyone with a piece of routing software,
however alpha, who would like to make some modifications to have it
recognize superways, or turn restrictions or signposting information
or something?
(c) The idea also needs "political" support. At some point in the not
so distant future, someone has to actually deploy the stuff on our
database server, and this is only going to happen if the powers that
be agree. As most of you know I'm only a very occasional visitor on
our IRC channel so I cannot argue for relationship support there. I
hope that those of you who like the idea will do their part to
overcome skepticism.
Thanks,
Frederik
--
Frederik Ramm ## eMail frederik at remote.org ## N49°00.09' E008°23.33'
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