[OSM-talk] Parking aisle as boundary of car park not showing

[80n]

On Thu, Sep 25, 2008 at 12:53 PM, Dave Stubbs <osm.list at randomjunk.co.uk>wrote:

> On Thu, Sep 25, 2008 at 11:47 AM, 80n <80n80n at gmail.com> wrote:
> > This is an interesting topic which is well worth discussion, but to
> return
> > to the original question for a moment.  The issue is that mapnik is not
> > capable of rendering a way that is both a path and an area.  The example
> > given was highway=service, amenity=parking.
> >
> > Regardless of whether people are centerlineists or not, there are always
> > going to be mappers who will tag ways this way.  We have a free form
> tagging
> > scheme so we cannot prohibit such things.  For example, a way tagged as
> > highway=waterway, power=line (two linear tags) might be unusual (water
> and
> > electricity generally don't mix ;) but we cannot disallow it.
>
> Umm... I don't like that argument.
>
> Saying we have a free form tagging scheme, and saying all the
> renderers should just cope with absolutely anything someone happens to
> have done are two very different things.
> We may not be able to "disallow" something, but we can sure as hell
> disagree with it and refuse to support it in a particular tool.
>
> Just because everything is "allowed" does not mean there is no such
> thing as "wrong" either, it just means our mechanisms for coping with
> it are different.
>
>
> >
> > So, if a way is tagged as highway=service to describe a road, but also
> > amenity=parking to indicate that the road *"is part of the car park and
> > defines its boundaries"* then that's the way it is.
> >
> > Suggesting that the data be changed to accommodate the deficiency of a
> > particular renderer is very much a case of mapping for the renderer.
>  This
> > is a principle that is important to uphold.  Fix the renderer not the
> data.
>
>
> And this is the point -- it's not a deficiency... as far as I'm
> concerned the car park has been incorrectly modelled.

There is no
> sense in tagging a feature as both a line and an area... that way
> madness lies.


You're proposing that a field with a hedge around it should be tagged as two
separate ways that share the same set of nodes right?

A single object tagged with landuse=field, border=hedge seems pretty
reasonable and intuitive to me.  Where's the madness in this?

In this case a renderer might choose to render the field as an area or the
border as a line or, indeed, both.

Sometimes it can be the renderer that needs to decide whether something is
rendered as an area or a line or even a point.  A roundabout being a good
example where at some low zoom level it could be an icon, at another it's a
filled in blob (an area), and at a high zoom level its a road with a hole in
the middle.

80n



> And tagging a way/area with more than one feature can be
> just confusing. One feature per object is an entirely sensible rule
> that people are of course free to ignore... just don't expect anything
> to ever work if people make a regular habit out of it. The problem is
> that all sense of predictability has just been thrown out... does this
> represent a road around a car park, a road in a car park, an area of
> service road you can park on, or a centre line of a service road you
> can park on?
>
> Dave
>
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