<div dir="ltr"><div>I render the things that OSM shows as cliffs, because sometimes surprises lurk between the contour lines. Otherwise, when I care, on my own maps I render elevation contours (and hence have no use for the cliff height in the data base). In a spot like <a href="https://kbk.is-a-geek.net/catskills/test3.html?la=42.1876&lo=-74.0397&z=14">https://kbk.is-a-geek.net/catskills/test3.html?la=42.1876&lo=-74.0397&z=14</a>, it's pretty obvious that there are cliffs about.<br><br></div>I do like the idea of having some sort of object for cuts and fills, because they're important features that often aren't in the elevation databases. Highway and rail embankments would kind of come along for the ride.<br></div><div class="gmail_extra"><br><div class="gmail_quote">On Tue, Nov 29, 2016 at 6:08 PM, Warin <span dir="ltr"><<a href="mailto:61sundowner@gmail.com" target="_blank">61sundowner@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<div class="m_3215297305207488891moz-cite-prefix">I would hope that a scheme can be had
that is one sided - and the same for cliff, embankment, cutting
etc. <br>
<br>
As such it should be one sided. After all another side could have
a different slope/area. A single sided scheme could be used for 2
sided or multi sided structures by many separate one sided OSM
entries, as many entries as required to represent the structure.
In this way the name of the structure has less relevance ... when
does an embankment become a cutting? A cutting a cliff? If the
result is the same .. then it does not really matter what it it
called, avoids arguments of things like masts vs tower, monument
vs memorial. <br>
<br>
One rendering, not OSM based, has cliffs in pink, the top with
spikes pointing downwards and the vertical rise stated as a number
in meters. <br><div><div class="h5">
<br>
On 30-Nov-16 09:57 AM, Lorenzo "Beba" Beltrami wrote:<br>
</div></div></div><div><div class="h5">
<blockquote type="cite">
<div dir="ltr">It makes sense that a road embankment have only one
slope.<br>
<br>
Perhaps for a levee[1] we need a specific tagging system because
a levee has always two slopes.<br>
<br>
I'm native of the Po Valley where levees are along every river
(Volker can confirm it ;) ).<br>
A levee for flood prevention could be simple[2] but even a wide
and complex feature[3] to map.
<div><br>
</div>
Lorenzo<br>
<br>
[1] <a href="https://en.wikipedia.org/wiki/Levee#River_flood_prevention" target="_blank">https://en.wikipedia.org/wiki/<wbr>Levee#River_flood_prevention</a><br>
[2] <a href="http://www.navecorsara.it/wp/wp-content/uploads/2010/01/Stirone_argine_1-580x435.jpg" target="_blank">http://www.navecorsara.it/wp/<wbr>wp-content/uploads/2010/01/<wbr>Stirone_argine_1-580x435.jpg</a><br>
[3] <a href="http://bur.regione.veneto.it/resourcegallery/photos/465_Guarda%20Veneta_ro_Panorama%20con%20argine.jpg" target="_blank">http://bur.regione.veneto.it/<wbr>resourcegallery/photos/465_<wbr>Guarda%20Veneta_ro_Panorama%<wbr>20con%20argine.jpg</a><br>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">2016-11-29 23:28 GMT+01:00 Kevin Kenny
<span dir="ltr"><<a href="mailto:kevin.b.kenny+osm@gmail.com" target="_blank">kevin.b.kenny+osm@gmail.com</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">
<div>'Embankment' is frequently used for a built-up
structure on a steep hillside that keeps a road,
railroad, or similar feature from sliding into a gorge
or river. See <a href="https://en.wikipedia.org/wiki/Embankment_%28transportation%29#/media/File:Embankment_1_%28PSF%29.png" target="_blank">https://en.wikipedia.org/wiki/<wbr>Embankment_%28transportation%2<wbr>9#/media/File:Embankment_1_%28<wbr>PSF%29.png</a>
for an illustration from Wikipedia. Except for the
portion crossing the tributary stream, the road in the
picture is clearly NOT banked on the uphill side, so the
embankment here is what Warin was describing as
'one-sided.'<br>
<br>
</div>
Locally to me, this is the commonest sense of the word. <br>
<br>
I am a native speaker of American English, and I live in
terrain heavily sculpted by the glaciers of the last Ice
Age, where highway and railroad embankments are relatively
common.<br>
</div>
<div class="m_3215297305207488891HOEnZb">
<div class="m_3215297305207488891h5">
<div class="gmail_extra"><br>
<div class="gmail_quote">On Tue, Nov 29, 2016 at 4:34
PM, Volker Schmidt <span dir="ltr"><<a href="mailto:voschix@gmail.com" target="_blank">voschix@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr"><br>
<div class="gmail_extra"><br>
<div class="gmail_quote"><span>On 29 November
2016 at 22:03, Warin <span dir="ltr"><<a href="mailto:61sundowner@gmail.com" target="_blank">61sundowner@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<div class="m_3215297305207488891m_1585881037483698941m_-6595638630347841077m_5528073053367767952moz-cite-prefix">Not
all embankment have 2 slopes <br>
</div>
</div>
</blockquote>
<div><br>
</div>
</span>
<div class="m_3215297305207488891m_1585881037483698941m_-6595638630347841077m_5528073053367767952moz-cite-prefix">To
my understanding of the English term, an
"embankment" is the equivalent of dyke or
levee and is a long, narrow man-made
elevation. Therefore they always have two
slopes of opposite directions (leaving out
the ends)<br>
<br>
</div>
<div class="m_3215297305207488891m_1585881037483698941m_-6595638630347841077m_5528073053367767952moz-cite-prefix">What
Martin proposes should get a different tag
name to distinguish it from an embankment.
The term "on-sided enmbankment" is used in
OSM for this, but I do not like it at all.
I strongly recommend to use a different
tag name. I used "slope" as this is the
term used to describe the inclined flanks
of levees (=embankments).<br>
</div>
<div>
<div class="m_3215297305207488891m_1585881037483698941h5">
<div class="m_3215297305207488891m_1585881037483698941m_-6595638630347841077m_5528073053367767952moz-cite-prefix"><br>
<br>
Length - simple set as the length of
the way. Cliffs are tagged as a single
way at the top of the cliff, with the
right hand side being 'downwards' when
facing the direction of the way. <br>
<br>
Vertical rise - could be tagged with
the height key.. this can vary over
the length of the feature (I have
found this on some maps as a number in
meters ... assumed to be the maximum
vertical locally rise in meters) To
accomodate teh change in vertical
height .. put the height on individual
nodes? <br>
<br>
Slope - or in OSM terms 'incline'.
This in OSM is entered as a way along
the top where the slope would be
minimal and not what 'we' want to
describe. ... as cliffs, cuttings and
embankments are best described this
way I think incline may not be the
best thing to tag? Humm stairs are
described using the incline key ...
but on a way that goes up .. leaving
the top and bottom free of this. So
maybe a top and bottom way .. with a
simple way from bottom to top
containing the incline information? <br>
<br>
While the 'top' and 'bottom' of
natural features can be a bit fuzzy
they are features that should be
mapped. Definition? Something for a
geologist? Along the lines of the line
formed by the intersection of the
average slope of land before the
change to the average slope of land
after the change ( the change being
the cliff, embankment or cutting)?
<div>
<div class="m_3215297305207488891m_1585881037483698941m_-6595638630347841077h5"><br>
<br>
<br>
<br>
<br>
On 30-Nov-16 01:25 AM, Volker
Schmidt wrote:<br>
</div>
</div>
</div>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<div>
<div class="m_3215297305207488891m_1585881037483698941m_-6595638630347841077h5">
<blockquote type="cite">
<div dir="ltr">
<div>If you want to micromap
slopes you should create a
new key "slope" or
something similar. An
embankment has two slopes.
It is equivalent to dyke
or levee. The one-side
embankments that are
defined in the OSM wiki,
are in reality slopes and
should be retagged
accordingly.<br>
<br>
</div>
Independently of the name
used fo the tag I see the
prblem of defining where the
slope starts, normally these
are rounded features.<br>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On
29 November 2016 at 13:48,
Martin Koppenhoefer <span dir="ltr"><<a href="mailto:dieterdreist@gmail.com" target="_blank">dieterdreist@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">
<div>
<div>
<div>
<div>
<div>Currently
we are mapping
only one side
of the
embankment (I
think it's the
upper side,
but am not
sure if the
wiki says this
explicitly),
with the
direction.
What we would
IMHO need is a
way to map the
lower side as
well and to
combine both.
A closed
polygon will
not work I
believe.<br>
<br>
</div>
The obvious
solution that
comes to mind
is a new
relation type:
in case the
upper end is
mapped, draw a
new way for
the lower end
and combine
both with a
relation
(possibly
assigning
roles like
upper and
lower, maybe
also draw
lateral ways
(ways that
connect the
ends of the
upper and
lower ways and
defines their
shape) in
cases they are
not straight).
(The type=area
relation does
this)<br>
<br>
</div>
Maybe it could
also be done
without the
relation, simply
by tagging the
upper and lower
ways
accordingly, and
connect them at
least at one of
their ends with
an explicit
lateral way (and
respective
tags). This
would require
from the data
user to
topologically
search for the
embankment area
in order to be
able to render
it (or make
other use).<br>
<br>
</div>
What do you think,
which
representation is
better? Are there
alternatives?<br>
<br>
</div>
Cheers,<br>
</div>
Martin<br>
</div>
<br>
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