[Tagging] Topographic Prominence for Peaks
kevin.b.kenny at gmail.com
Sun Sep 23 23:29:49 UTC 2018
On Sun, Sep 23, 2018 at 5:40 PM Joseph Eisenberg
<joseph.eisenberg at gmail.com> wrote:
> Yes, “prominence” here is a technical term that has only a partially connection to the subjective “importance” of a peak.
> In general, all peaks with high topographic prominence are considered important by local people (if anyone lives near them) and mountain climbers, but some peaks with low topographic prominence are also well-known, eg the Matterhorn.
> I see that the old, abandoned proposal also suggests the possibility of making a relation to show the parent peak and key col. These sort of relations may not be useful to data users, but they might help other mappers to verify the prominence data.
> Personally, I won’t add new relations when the key col and parent peak are close by, but I will if they are far away.
Exactly. None of our data model is set up to say, "you must map all
features of a given place." It's more, "if you're mapping *this*,
consider mapping *that* as well, and here's how to represent it."
And yes, when key col and parent peak are distant, it gets weird. As a
quick test, I looked up Slide Mountain in the Catskill Mountains of
New York https://www.openstreetmap.org/node/357602650 elevation 1276
m, prominence 1000 m. I would have guessed that its line parent would
be on the way to Killington Peak, Vermont
https://www.openstreetmap.org/node/3139475460, which is both the
nearest higher peak and the nearest more prominent peak, but in fact,
the deep valleys of the Hudson and Mohawk rivers mean that the line
leads away, with a key col somwhere near
https://www.openstreetmap.org/#map=15/42.1653/-76.8190 and the next
higher point being an insignificant knoll in the Monongahela National
Forest in West Virginia. Who knew?
By contrast, it mighn't be worthwhile mapping the key col and line
parent for Hunter Mountain
https://www.openstreetmap.org/node/357598537 - its parent is Slide
Mountain (link above) and the key col is somewhere in the pass near
the Bellearyre ski resort
In any case, the point remains that topographic prominence is a
completely objective metric; it can be computed from a sufficiently
accurate DEM; but is computation is sufficiently onerous that it's
worthwhile capturing and recording the results.
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