I would hope that a scheme can be had that is one sided - and the same
for cliff, embankment, cutting etc.
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.
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.
On 30-Nov-16 09:57 AM, Lorenzo "Beba" Beltrami wrote:
It makes sense that a road embankment have only one slope.
Perhaps for a levee[1] we need a specific tagging system because a
levee has always two slopes.
I'm native of the Po Valley where levees are along every river (Volker
can confirm it ;) ).
A levee for flood prevention could be simple[2] but even a wide and
complex feature[3] to map.
Lorenzo
[1] https://en.wikipedia.org/wiki/Levee#River_flood_prevention
<https://en.wikipedia.org/wiki/Levee#River_flood_prevention>
[2]
http://www.navecorsara.it/wp/wp-content/uploads/2010/01/Stirone_argine_1-580x435.jpg
[3]
http://bur.regione.veneto.it/resourcegallery/photos/465_Guarda%20Veneta_ro_Panorama%20con%20argine.jpg
2016-11-29 23:28 GMT+01:00 Kevin Kenny <kevin.b.kenny+...@gmail.com
<mailto:kevin.b.kenny+...@gmail.com>>:
'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
https://en.wikipedia.org/wiki/Embankment_%28transportation%29#/media/File:Embankment_1_%28PSF%29.png
<https://en.wikipedia.org/wiki/Embankment_%28transportation%29#/media/File:Embankment_1_%28PSF%29.png>
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.'
Locally to me, this is the commonest sense of the word.
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.
On Tue, Nov 29, 2016 at 4:34 PM, Volker Schmidt <vosc...@gmail.com
<mailto:vosc...@gmail.com>> wrote:
On 29 November 2016 at 22:03, Warin <61sundow...@gmail.com
<mailto:61sundow...@gmail.com>> wrote:
Not all embankment have 2 slopes
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)
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).
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.
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?
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?
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)?
On 30-Nov-16 01:25 AM, Volker Schmidt wrote:
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.
Independently of the name used fo the tag I see the
prblem of defining where the slope starts, normally these
are rounded features.
On 29 November 2016 at 13:48, Martin Koppenhoefer
<dieterdre...@gmail.com <mailto:dieterdre...@gmail.com>>
wrote:
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.
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)
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).
What do you think, which representation is better?
Are there alternatives?
Cheers,
Martin
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