<html><head></head><body><div style="color:#000; background-color:#fff; font-family:Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:13px"><div id="yiv5164078795"><div>
<div class="qtdSeparateBR"><br><br></div><div class="yiv5164078795yqt4549737207" id="yiv5164078795yqtfd89818"><div class="yiv5164078795moz-cite-prefix">On 24/09/2018 07:03, Joseph Eisenberg
wrote:<br clear="none">
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<div id="yui_3_16_0_ym19_1_1537797574808_2641">Right! Especially on my island, New Guinea. </div>
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<div id="yui_3_16_0_ym19_1_1537797574808_2642">That’s why we need to check the height of
saddles and peaks “by hand”, or better yet by survey with GPS.</div>
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<div>OSM is the right place for this data, and some map
styles and database users will find it useful to analyze data
about mountain areas and peaks.</div>
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<div>For example, even those lists of “tallest peaks”
actually use topographic prominence as a cutoff. Otherwise the
highest peaks on Earth would all be rocks and bumps on the
slopes of Everest. </div>
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<div>Most of us just estimate the prominence of a peak
intuitively, before choosing to add one to the map. Clearly, a 5
meter tall bump isn’t a peak. Perhaps a 10 meter rise may have a
name in England or Denmark, where mountains are scare. In other
contexts a peak won’t be named unless it is 100m or 200m above
the nearest saddle on a ridge. </div>
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<div>Joseph</div>
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<div class="yiv5164078795gmail_quote">
<div dir="ltr">On Mon, Sep 24, 2018 at 12:59 PM Yves <<a href="mailto:yvecai@mailbox.org" target="_blank" rel="nofollow" shape="rect" ymailto="mailto:yvecai@mailbox.org">yvecai@mailbox.org</a>>
wrote:<br clear="none">
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<blockquote class="yiv5164078795gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">I don't
see no issue in mapping prominence for those interested in.<br clear="none">
Just to mention for the sake of the discussion that
'sufficiently accurate DEM' doesn't exists globally.<br clear="none">
Yves _______________________________________________<br clear="none">
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</div><pre><div class="yiv5164078795yqt4549737207" id="yiv5164078795yqtfd57735">_______________________________________________
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<div>A few points on this thread:</div>
<div>* Prominence has been added for every significant peak in
Scotland (along with which hill-bagging group they are members
of). The peaks called Marilyns (a play on the more famous Munros -
peaks over 3000 ft) are entirely based on prominence, and are
sufficiently well known in the UK to have a guidebook. Overpass
query: <a class="yiv5164078795moz-txt-link-freetext" href="http://overpass-turbo.eu/s/Cbi" target="_blank" rel="nofollow" shape="rect">http://overpass-turbo.eu/s/Cbi</a></div>
<div>* What Michael describes sounds very much like something close to
topographic isolation
(<a class="yiv5164078795moz-txt-link-freetext" href="https://en.wikipedia.org/wiki/Topographic_isolation" target="_blank" rel="nofollow" shape="rect">https://en.wikipedia.org/wiki/Topographic_isolation</a>).
Co-incidentally I looked at calculating something like this after
a recent conversation with Stefan Keller (prompted by a wikipage
on Dominance:
<a class="yiv5164078795moz-txt-link-freetext" href="https://wiki.openstreetmap.org/wiki/User:Maxbe/Dominanz_von_Gipfeln" target="_blank" rel="nofollow" shape="rect">https://wiki.openstreetmap.org/wiki/User:Maxbe/Dominanz_von_Gipfeln</a>).
I simply calculated the closest, higher peaks for all Swiss peaks
and then filtered by that distance (e.g. over 5 or 10 km). This
produces a reasonably good distribution of peaks (see
<a class="yiv5164078795moz-txt-link-freetext" href="https://www.dropbox.com/s/qoe2y9d6n6pjh0c/ch_peak_iso.jpg?dl=0" target="_blank" rel="nofollow" shape="rect">https://www.dropbox.com/s/qoe2y9d6n6pjh0c/ch_peak_iso.jpg?dl=0</a>),
and can obviously be adjusted by other parameters.</div>
<div>* One problem with prominence is that it is probably most easily
obtained from non-open sources (such as those used to populate
wikipedia), and equally there is temptation to use copyright maps
for information on saddle points. For the peaks with a very
significant prominence (say 1000 m or more) this is less of a
problem as most can be deduced very quickly.</div>
<div>* Peak names can be an issue when the high point is part of a
group of peaks with an encompassing name (Dufourspitze Monte Rosa,
Breithorn Occidentale/Westgipfel comes to mind). The Matterhorn
traditionally has 2 summits (the Swiss & Italian ones), but
only one is mapped, avoiding this issue for that peak.<br clear="none">
</div>
<div>* Many peaks which sit on national boundaries are not on located
as part of the border way on OSM, and may therefore not be
included in peaks with a country filter. There are several
examples near Zermatt.</div>
<div>Thanks to Kevin Kenny & others who have pointed out the
theoretical value of prominence.</div>
<div id="yui_3_16_0_ym19_1_1537797574808_2644">Jerry</div><div class="yiv5164078795yqt4549737207" id="yiv5164078795yqtfd99965"><br clear="none">
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