[Tagging] better mapping for embankments / slopes

Warin 61sundowner at gmail.com
Tue Nov 29 23:08:52 UTC 2016


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+osm at gmail.com 
> <mailto:kevin.b.kenny+osm at 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 <voschix at gmail.com
>     <mailto:voschix at gmail.com>> wrote:
>
>
>
>         On 29 November 2016 at 22:03, Warin <61sundowner at gmail.com
>         <mailto:61sundowner at 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
>>             <dieterdreist at gmail.com <mailto:dieterdreist at 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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