On Thu, Sep 25, 2008 at 1:22 PM, 80n <[EMAIL PROTECTED]> wrote: > On Thu, Sep 25, 2008 at 12:53 PM, Dave Stubbs <[EMAIL PROTECTED]> > wrote: >> >> On Thu, Sep 25, 2008 at 11:47 AM, 80n <[EMAIL PROTECTED]> 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?
Sounds pretty sensible to me too. Border implies it's a property of the field, and you don't normally use hedges for anything else. If we get really super accurate you /might/ find someone mapping hedge areas, and wondering whether you mapped the centre line or not, but I doubt it. Here's another: military=airfield, border=fence, fence_height=3, fence_type=chain_link_with_razorwire, highway=unclassified. Where's the fence/road? > > 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. > Absolutely true. Dave _______________________________________________ talk mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk
