[Tagging] Additional detail of Levee mapping via embankments

Richard ricoz.osm at gmail.com
Tue Nov 12 18:44:20 UTC 2019

On Tue, Nov 12, 2019 at 01:53:55PM +0900, John Willis via Tagging wrote:
> > On Nov 12, 2019, at 10:26 AM, Joseph Eisenberg <joseph.eisenberg at gmail.com <mailto:joseph.eisenberg at gmail.com>> wrote:
> > 
> > If you are mapping an area, as in this case, just use a closed way or multipolygon.
> How would a closed way (area polygon) denote “top” and “Bottom”? 
> if embankments can be easily expressed as a single simple polygon, how data users infer “top” and "bottom” from that is beyond me. 
> That is the issue: I don’t understand how a polygon would represent that, and I think those two different pieces of mapping need to be explicitly tagged. 

do not search the problem on your side of the screen:)

We need new tags for the bottom of embankmets, top of cuttings, bottom of cliffs, earth_banks 
and maybe a few others if we want to map them.

Imho all those should be tagged ways such as cliff:base, relations could be used optionaly
to relate a particular cliff edge to a particular cliff base which would define the
area of the slope.

Here is what I see:
* man_made=embankment_base or man_made=embankment:base
* man_made=cutting or man_made=cutting:top - top edge of cutting in analogy to 
  man_made=embankment (126 pieces in database but straightforward to extend)
* natural=cliff_base or natural=cliff:base
* natural=earth_bank_base or natural=earth_bank:base

I would favor the ":" variants, it might have been nicer if we had a scheme like
cliffe:edge and cliff:base and same for cutting, embankment, earth_bank from the 
beginning. The "old" defs like man_made=cutting can be left or man_made=cutting:base
can be defined as an alias.


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