[OSM-talk] displayed width of roads

Colin Marquardt colin at marquardt-home.de
Tue Feb 19 21:59:49 GMT 2008


"Dave Stubbs" <osm.list at randomjunk.co.uk> writes:

> On Feb 18, 2008 11:21 PM, Frederik Ramm <frederik at remote.org> wrote:
>> Hi,
>>
>> > > By co-incidence, I was in contact with another mapper who's been doing
>> > > something like this to make low zoom osmarender rendering a bit
>> > > prettier. What's everybody's opinion of this kind of practice? Is it
>> > > not an example of compromising the data (which we want to endure) to
>> > > work around a temporary deficiency in one particular renderer?
>> >
>> > If the slip roads are not really underneath the other roads then
>> > yes it is definitely wrong (IMHO). The layer tag is meant to describe
>> > the physical ordering of the roads on the ground.
>>
>> I've had a similar situation on the talk-de list where some people
>> seem to have started adding layer=1 to tram tracks. I don't like this
>> all that much (a bridge leading over a road with tram tracks would
>> then need to be layer=2 etc) but it's hard to argue with them since
>> the tram tracks *are* on top of the road. The layer tag doesn't say by
>> how much...
>
> People take things written down too seriously, I'd argue that if a
> human being can step over it it doesn't count (at a bare minimum).
> I'm sure they think this too but just want tram tracks to appear above
> roads, which is probably a sensible idea, but this isn't the way to go
> about it.

We had discussed this on IRC, and while jburgess and steve8 say it's
possible to modify osm2pgsql/Mapnik to always draw railways on top of
highways (unless the layer tag says otherwise), people had objections
because then some railways close to, but not *in* highways, might
obstruct the highways (and possibly the name), and the highways were
seen as more important.

jburgess says it might be possible to separate out trams and light_rails
from all the other railway tags and only raise these in z-order, but who
knows if this is enough... Another suggestion (from Sfan00) was having
another tag for such "in street" railways.

Cheers
  Colin





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