[Tagging] Elevation and height on vertical features

[Warin]

On 8/01/2016 3:32 AM, Christoph Hormann wrote:
> 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.
>

Consider who is going to use the map, and for what purpose.

The most critical use is for aeroplanes .. where the maximum height is 
critical information!
I think for that reason alone most maps should indicate the maximum 
elevation of an object.