[Tagging] Elevation and height on vertical features

[Christoph Hormann]

On Thursday 07 January 2016, Aaron Spaulding wrote:
> Hi all,
>
> I’ve been working on generating 3D meshes based on OSM data and I ran
> into a problem. Vertical features like 'natural=cliff',
> 'barrier=retaining_wall’ and 'waterway=waterfall' occupy two points
> in physical space, but because of the 2D nature of OSM its ambiguous
> which side of the feature that the ‘ele’ tag applies.

For cliffs mapping conventions say that you should put the line on top 
of the cliff in case it is not exactly vertical - accordingly the ele 
tag would also refer to the top  - but keep in mind that the elevation 
does not have to be constant.

-- 
Christoph Hormann
http://www.imagico.de/