[Talk-us] Relations and boundaries

[Toby Murray]

On Thu, Mar 3, 2016 at 1:48 PM, Frederik Ramm <frederik at remote.org> wrote:
> Hi,
>
> On 03/03/2016 08:02 PM, Steve Friedl wrote:
>> I’ve been updating all the cities in Orange County California to have fully
>> segmented relationalized boundaries, such that cities sharing a common
>> border share a single way in each of their relations; this eliminates
>> overlapping ways.  It’s been very tedious but it's really getting cleaned
>> up.

Nice. I did the same with county relations a while ago and yes, it is
very tedious. While you're doing that are you also putting wikipedia
tags and adding nodes to the relations? I did this with counties and
talked about it in a blog post a while ago. Some of the same things I
talk about in the blog post likely apply to cities as well:
http://ksmapper.blogspot.com/2014/02/county-borders-in-openstreetmap.html

>> First: The individual relations – city, county, national forest, etc. – all
>> have full information tags about the entity, but how should the way members
>> themselves be tagged?
>
> It is not necessary but may add clarity for people editing the data.
> Generally it is recommended to tag boundary=administrative,
> admin_level=<highgest admin level involved>, and no names (no
> county:left, county:right stuff etc either).

Agree with Frederik here. A completely tagless way is more likely to
be deleted or otherwise messed with by people who don't know the
details of boundary relations so I typically leave the
boundary=administrative and admin_level tags on them.


>> Within Westminster is a "donut hole" , and the Westminster relation has it
>> as a role=inner.
>>
>> Question: should that same donut hole be tagged role=outer in the Orange
>> County relation?
>
> Yes, that's what I would suggest. It would be nice if our tools allowed
> you to simply make the Westminster *relation* an "inner" of Orange
> county and thereby automatically do the donut justice but that's not
> supported by anything really.

Disagree here. As Peter said, when you enter the city you aren't
leaving the county (Independent cities in Virginia are a different
story) so you don't need to do anything with it. There have been some
instances of people using "subarea" relation memberships but I don't
really agree with that myself. Especially in the case of
cities/counties since cities sometimes spread into multiple counties.
See the United States boundary relation for an example of this:
http://www.openstreetmap.org/relation/148838

Note that all the state boundary relations are members of the U.S.
relation with a role of "subarea" - and to reiterate, I do *not*
recommend doing this :)

Toby