A land form ridge too me isa long, narrow raised part of a high edge formed by hill/mountains and
there associated bits. A land form of a dividing range or continental
divide does not have to be narrow, The 'dividing line' marks the
separate water flow from one side to the other and should be 'long'. So
I don't think a divide/range is a ridge necessarily. In fact a divide
could have several ridges as part of the divide. Some sample
divides/ranges? Andes 7,000 km https://en.wikipedia.org/wiki/Andes Rocky
Mountains 4,800 km https://en.wikipedia.org/wiki/Rocky_Mountains Great
Dividing Range 3,500 km https://en.wikipedia.org/wiki/Great_Dividing_Range
The last exists in OSM as an area Way211234843
<https://www.openstreetmap.org/way/211234843> tagged as
fixme=More accurate/better representation/make relation
fuzzy=50000
name=Great Dividing Range
name:cs=Velké předělové pohoří
name:de=Australisches Bergland
name:es=Gran Cordillera Divisoria
name:nl=Groot Australisch Scheidingsgebergte
natural=mountain_range
source=OpenCycleMap terrain rendering
source:name=local_knowledge
wikidata=Q192583 <https://www.wikidata.org/wiki/Q192583>
There are 87 natural=divide in the data base ...
no wiki page to say what it is, looks to be used by North America
Sample found: Relation1643366 <https://www.openstreetmap.org/relation/1643366>
tagged as
FIXME=continue
name=Sierra Crest
natural=divide
route=natural
type=route
----------------
I do agree that a true ridge line may not point uphill all the time, but still
be a single ridge.
On 05/10/18 01:54, Tobias Zwick wrote:
The definition in the wiki is a bit contradictory, in my opinion. On the one side, it
states the thing about that the arrows should point away from the saddle point towards
the peaks, like steps or a oneway street, on the other side it describes a ridge to
connect several peaks and saddle points. Tagging the whole ridge as one way would be
impossible if you followed that "arrow points upward" rule.
There is also no mention of that rule in the original approved proposal. Looking at the
history of the article, that rule was added in January 2018, following a short, well
"discussion" about how a ridge could be rendered.
The change made amounts to a incompatible, as your enquiry shows, redefinition
of the ridge tag because one cannot anymore correctly tag a whole ridge as one
way.
We have two options to go from here:
1. Revert that definition change, continue to allow tagging ridges as one way
spanning over several peaks
2. Leave the wiki definition as it is currently and you tag "name=Catskill
Divide" on every of the multiple natural=ridge ways you'd have to create along the
whole way
I'd favour the first option because
1. Redefinition of an existing tag is a no go
2. The reason why the definition was changed was to make it easier to render a
ridge in a certain suggested way. Don't know if it is even rendered this way
now (on osm-carto), but in any case this'd be tagging for the renderer, as the
information where the ridge goes up and where it goes down is already present
in the peak/saddle nodes
Cheers
Tobias
Am 4. Oktober 2018 16:46:19 MESZ schrieb Kevin Kenny <[email protected]>:
In some maps that I render, I want to show the divide between a couple
of major river basins. (I have a good DEM for the area in question and
can derive the line readily.)
In light of the recent thread on topographic prominence, I wonder if
this is sufficiently interesting information at least to push it to
OSM. (If not, that's fine, I have a PostGIS database and a bucket of
shapefiles and know what to do.)
If it is sufficiently interesting, the question then arises: how to
map/tag it?
'natural=ridge' comes to mind, and the divide in question has a local
name. (The 'Catskill Divide' separates the basins of the Hudson and
Delaware Rivers.) This approach appears to run into problems, as I
read the Wiki. I see:
The way should connect saddle points and peaks, and the arrows should
point upwards.
That may be all right for a ridge ascending the flank of a single
mountain, but what I'm talking about is the spine of a range, with the
ridge traversing dozens of named peaks. Even with a single mountain,
if there are false summits, the arrows on a single way cannot point
upward all the time! (And the wiki is clear that the
Do I misread, and should the reading instead simply be that the
arrowhead should be higher than the arrow tail? In that case, I could
break the divide into two ways, with a common endpoint at the highest
summit in the range.
Consider this a low-priority item. I have (or will have - there is a
bit of debugging yet) the data. I know how to render them. I'm happy
enough with a shapefile or a private PostGIS table if others aren't
interested.
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