[Talk-us] Relations and boundaries

Steve Friedl steve at unixwiz.net
Thu Mar 3 19:02:44 UTC 2016


Hi all,

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.

So a few questions:

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?

I’ve seen some OSM notes that say the ways can be tagged too, but I’m not
sure how. There’s no common name, and there may not even be the same admin
level (a city boundary on the border of a county would have two admin levels
for the given way.

My experience is that if the relation is fully tagged, and one of the ways
is tagged with the same info, we see duplicate city names along the border,
as the renderer takes the name from both the relation and the way. 

I am not sure I see any value *other than* tagging it as a boundary, with no
other information. But I’d really like to do this right.

Second: I’m not sure how to handle quasi-enclaves.  Orange county is made of
many cities, and a few cities contain some small *county* regions - think of
them as donut holes. I don't know how to handle this.

The Orange County relation is tagged with

	boundary = administrative
	border_type = county
	admin_level = 6

The city of Westminster relation (fully inside Orange County) is tagged with

	boundary = administrative
	border_type = city
	admin_level = 8

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?

It just doesn't feel right to have a role=outer fully within another
role=outer, but that's the only way I can think of to handle this.

Or do we just assume that because this donut hole has been excluded from the
City of Westminster, it's automatically part of the next outer item (in this
case, Orange County). The renderer doesn't identify any parts of the
donut-hole boundary.

The hole in question:
http://www.openstreetmap.org/#map=17/33.73488/-117.98422&layers=N  it's just
to the west of Star View Elementary School  There are many of these in
Orange County.
	
Steve
--- 
Stephen J Friedl  | Security Consultant | UNIX Wizard | 714 345-4571
steve at unixwiz.net | Southern California | Windows Guy |  unixwiz.net





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