[Tagging] Additional detail of Levee mapping via embankments

John Willis johnw at mac.com
Tue Nov 12 04:53:55 UTC 2019

> 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. 

Perhaps it is because while I have 3000+ edits, I rarely use relations or other complex mapping data structures, nor understand exactly what data consumers can infer from data vs what they need explicitly tagged to be useful (as I am not a data user) - but I assume that “top” and "Bottom” are difficult to infer, as slope data needs to be explicitly tagged to ways. 

I thought that the way (man_made=embankment [top]) + a polygon to represent the bank (area:man_made=embankment) would, together, represent the top and the area of the embankment, allowing inference of the direction of the slope. Perhaps an additional line for “bottom” would be necessary too. 

Two embankments would represent the slopes of the levee, while the man_made=dyke way would represent the path of the protection structure as a whole, as the embankments (particularly the outer one) are not continuous - but the levee (as a complete structure) is continuous. 

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