[OSM-talk] Nested areas

[spaetz]

On Thu, Jun 05, 2008 at 08:14:02PM +0100, Jon Burgess wrote:
> On Thu, 2008-06-05 at 19:49 +0200, spaetz wrote:

> > Why should it work differently? If I want a tunnel under a forest, a
> > layer=-1 *should* draw the tunnel under the forest. Why do you think
> > it's doing something wrongly? 
> 
> If the tunnel becomes invisible because the forest is drawn on top then
> that does not look good. If however the tunnel was drawn over the top
> with an appropriate style then that may be more useful. Mapnik would
> render the tunnel on top of the area but using a dashed style.

OK, tunnel is a bad example on my side. But there are things that I want in the data, but not drawn in regular maps. Think of a dug in powerline (some maps might want to show these too, I know...).

> > tagging a river with layer=-1 seems wrong to me on the other hand.
> Buildings are often constructed over the top of rivers. Whether the
> building is +1 or the river is -1 surely just depends on where you take
> your ground reference. If the river really flows through the building
> then I guess the layer tag is not the right answer.

If you do that for the river part that goes through/under a buiding, then I agree. I have tagged river bits under bridges with -1 myself.

But if you tag a river universally over quite a bit with layer=-1 just for the fun of it, as was in the original example, then this looks weird. And osmarender is right to make it look weird, isn't it?

> A similar issue must occur frequently with railway lines through train
> stations.

I'd think so, yep.

spaetz