[talk-au] Bridges and Tunnels

[Ross Scanlon]

> On Mon, Jun 7, 2010 at 2:18 PM, Ross Scanlon <info at 4x4falcon.com> wrote:
> > Each bridge that currently does not have a layer tag would have layer=1 added.
> 
> That will be incorrect if a bridge crosses a body of water (or other
> object) that has a layer tag other than zero. Which means some
> renderers may go from currently rendering something correctly, to
> rendering it incorrectly as a result of that change.

And they are possibly rendering incorectly at the moment as it's assuming layer=0.
 
> > Each tunnel that currently does not have a layer tag would have layer=-1 added.
> 
> Likewise.

Ok. So we add a fixme tag instead and something along the lines of "fixme=Does this need a layer tag?".  These show up correctly on keepright and josm validator and are more of a prompt to do something about it.
 
> > The script does the changes in small chunks, (configurable but currently set at maximum 100 ways), so it is easy to look through each changeset to see what has been added.
> 
> Is anyone planning to do this? You said there are 2500 instances. I
> don't think it's reasonable to make a massive change and leave
> checking them as an exercise for the reader, without putting in place
> some kind of process to actually check them.

I intended that if there was a problem then any user could find the changeset easily and then advise me of the problem and I could go back and alter it or they could alter it.

It's a lot easier to look through 100 ways than 2500 ways in one change set.

> Incidentally: how do current renderers (principally mapnik and
> osmarender) currently behave? Are any of these assumed defaults
> actually implemented, or have I got my wires crossed?

unknown.

--
Cheers
Ross