[Tagging] Peak-based mountain range proof of concept

[Brian M. Sperlongano]

On Tue, Dec 29, 2020 at 3:40 AM Joseph Eisenberg <joseph.eisenberg at gmail.com>
wrote:

> Some other issues: it appears that this relation is mostly the same as the
> set formed by "all natural=peak features in the State of Vermont", with
> some omissions which are hard to explain.
>

Not even close.  There are 1,313 natural=peak objects (
https://overpass-turbo.eu/s/11Ip) in the state of Vermont, so this relation
is only 16% of those objects.


> Why doesn't the mountain range continue south into Massachusetts or north
> into Canada? Is this a Vermont-only concept? Why is it only including the
> peaks in the center of Vermont, but not the hills farther east or west?
>
> Why not include https://www.openstreetmap.org/node/356555077 when 3 peaks
> just a kilometer to the west are included? (Perhaps that is just because
> this is an experiment?)
>

I went with what I could objectively verify with the help of local
knowledge.  The Green Mountains are not the only mountain range in Vermont,
there is also the Taconic range which runs through Vermont and over the
line into New York.  It's west of US7 in southern Vermont, and there are a
few mountains in the "Green Mountain National Forest" that are actually
part of the Taconic range.  Part of the discussion was "should foothills be
included?" - and the answer was that "Vermonters wouldn't consider the
foothills to be part of the mountains".  So, I specifically attempted to
exclude them.  I excluded anything with "Hill" in the name which eliminated
both the foothills and many (but not all) of the sub-peaks.

The initial data set was formed by pulling down a rectangle around VT with
natural=peak objects, then filtering out for elevation so I could pick out
the parallel spines that make the shape of the mountain range that matched
the rough shape of where I understood the range to be.  (I've done some
hiking in the GM, but certainly not enough to declare any sort of local
knowledge).  From that starting point, I consulted actual local knowledge
to figure out what to add or subtract from that set.

Regarding Canada/Mass - I didn't extend the range into those places simply
because I didn't have a license-compatible data source that could tell me
which peaks should be included.  It certainly should extend into Canada,
but the southern portion in Mass is questionable, as the peaks there seemed
to be just foothills and locally described as "The Berkshires".

I freely admit that there are parts of the Green Mountains missing from
that relation, but I'm quite confident that all the peaks I did include ARE
in the Green Mountains.  But, the imperfection of my ability to gather all
of the data is all a side show.  The point is that I'm demonstrating an
(experimental) method of mapping a mountain range.

While mountain ranges are "roughly linear", there is not always a single,
clearly defined spine (as you might find for Hawaii's Koʻolau Range, which
is the rim of an ancient volcano).  There are sections of the Green
Mountains that do have clear spines, for example the area around Stowe and
Waterbury have two clearly defined spines, one on either side of the
towns.  It would certainly be a mistake to run a linear feature through
downtown Stowe and call it the "spine" of the Green Mountains.  However, in
the southern parts, the mountains spread out more and would be poorly
represented by linear features.

Across the spectrum of mountain ranges, you'll find both ranges with
clearly defined spines as well as ones that are composed of a broad swath
of mountains in only a loosely linear layout.
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