[OSM-newbies] Administrative boundaries

[James Ewen]

On Sun, Nov 9, 2008 at 4:09 PM, Thomas Wood <grand.edgemaster at gmail.com> wrote:

>> So if you tag a relation as an administrative boundary, that's not
>> going to render?
>
> It will render based on how the ways are tagged. However, relations
> should still be added and tagged for data-completeness, and future
> possible uses of them.

> My interpretation of the border tagging method is 1 way representing
> the shared Strathcona and Edmonton border, as opposed to one
> representing each county.

Okay, can I tag a way as a road, and also as an administrative
boundary? I think my biggest problem was trying to create ways that
defined an area, for each area, and also the roadway all in the same
spot. But, at that time, that's what the wiki instructions said to do.

> Stacked ways is an issue with the editors, none of them support it
> particularly well, but potlatch probably is trickiest.
> Select a node that has two ways sharing it and hit / to cycle between
> the ways that use it.

I knew there was a '/' in there somehow, I've been trying to get that
to work, but I've been selecting the ways, not the nodes!

So, is there a way to define two adjacent areas that share a common
border without stacking ways on top of each other?

> I'm going to use JOSM to look over the data you've got entered, it's a
> much better editor for the large-scale edits of borders. Plus it's
> slightly easier to see overlapping ways (middle clicking)

I have yet to figure JOSM out... Potlatch seems to be a much better
editor. I've seen an into to JOSM video, but when I try to use JOSM,
it seems to be much more work, and a lot less intuitive to use.
Perhaps someone has a link to somewhere that shows the power of JOSM
for those of us who can't figure it out.

> Ok, the first thing I note is that all the ways are tagged
> boundary=civil, rather than boundary=administrative.
> A minor point is that the names aren't strictly supposed to be defined
> by left and right tags but conty:left and county:right (or something
> similar, I can't remember the exact scheme, but left and right will do
> for now :)

Again, this was copying the example found on the wiki. Since things
are evolving every day, I'm never right!

> I note that several sections of the Edmonton border are duplicated, in
> particular, it seems that 3 identically tagged borders run over the
> north west corner of the city.

That could be... ways laid on top of ways with no idea there are ways
already there. There are a couple of us working in the area, so that
might explain things as well...

> Here's where I should say "don't tag for the renderers", although it's
> nice to see the data, they cannot possibly show all features at all
> zoom levels. I know there is particular issues with these lowzoom
> situations. There's currently no easy way for them to filter by the
> size of a feature to bring it up to the lower zooms without
> compromising the look of more densely packed areas.

If you don't tag for the renderers, then you need to change the
renderers for the tags! There's a problem with that though, because if
you change the renderer, it affects everyone world wide. If you simply
change the admin_level that you use, it will only affect your area.

So, in Canada where everything is far apart, use admin_level 2 for
provincial borders, but in an area like Belgium, where I can fit the
whole country on screen at zoom level 8, provincial borders are set at
admin_level 6. It would make more sense to allow the local users to
determine what zoom levels certain features should show up at in their
area, rather than trying to make a global list that works for
everyone.

I guess what I'd like to see is a way to be able to tag other items
with optional zoom level extents. One of the problems I have here is
that the City of Edmonton with >750,000 people doesn't get labeled
until you're in really close (zoom 8). At zoom 5, Canada is a blank
canvas as far as any cities are concerned. At zoom 6, Fort
Saskatchewan (15,000), Spruce Grove (19,500), and Leduc (17,000) names
get rendered, but the provincial capital remains hidden.

The solution offered by others is to move the name the City of Spruce
Grove out of the way so Edmonton can be displayed. That not only
sounds like tagging for the renderers, but that also means that I
would have to tag an area a couple miles outside the City of Spruce
Grove with the tag for the city name. Being able to put an optional
display level tag would solve this issue.

James