[Tagging] Additional detail of Levee mapping via embankments

Richard ricoz.osm at gmail.com
Mon Nov 18 21:51:34 UTC 2019


On Mon, Nov 18, 2019 at 11:15:49AM +0900, Joseph Eisenberg wrote:

> 
> 1) Map the central line as man_made=dyke, or highway + cutting=yes /
> embankment=yes as relevant. This line should not be 100 kilometers
> long, but a reasonable length: probably no more than 10 kilometers,
> and even shorter in a major city.
> 
> This step is enough for most uses. You don't actually have to do steps 2 or 3.
> 
> 2) If you want to, you can map the top line of any man_made=embankment
> lines, if desired.
> 
> 3) Finally (this part is very optional), you could map the area of the
> cutting or embankment or dike as a series of closed ways. Don't make
> them more than a kilometer or 2 long, since it's a pain to edit them
> if they are too huge. It's better to use a few smaller closed ways
> rather than a huge multipolygon to map complex features with holes.

a couple of points:
* people may confuse what the "area of embankment" is, my intuition is this 
  would be the top area of the embankment not the slope of it as you perhaps
  intend it.
* still thinking in most case it would be better to map eg the bottom edge of
  the embankment where there is a clear cut bottom edge as it much easier 
  than mapping a slope area. If you map both the edge of the embankment and
  the slope, the top ways will be "shared", which means either a multipolygon 
  or drawing the ways on top of each other. Slope areas would typically get 
  another area attributes (surface, landuse, vegetation), again to be solved 
  with multipolygons or the hacky way.
* the comparison with riverbanks may miss some points: rivers are named so 
  they are easier to piece together. Two adjacent embankment areas may be 
  a valid attempt to map an edge of an embankment for example.
  River areas are just water and don't have any other landuse or vegetation
  attributes.
* it would be nice to have a concept that extends easily to earth banks, cliffs
  and cuttings.

> (We should not use a new tag like man_made=levee for this, because
> "levee" is American English for "dike", so it would be better to use
> man_made=dyke_area or something similar.)

After googling dyke I am wondering if we should make an exception and use 
American English in this very particular case ? Googling levee gives me much
more useful information than "dyke".

Other than that, "dyke_area" or "area:dyke" in analogy to 
https://wiki.openstreetmap.org/wiki/Key:area:highway ?


Richard




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