[Talk-us] Elevation in local units

[Lars Ahlzen]

On 03/25/2015 01:43 AM, Bryce Nesbitt wrote:
>
>   * I feel that osm convention should encourage all mappers to specify
>     units (e.g. 22 m).
>   * That whitespace should be allowed (e.g. 22m, 22 m, or even 22 meters).
>   * And that local units should be encouraged (e.g. 22 feet, or 22' 0").
>
> The wiki templates, if spruced up, could define the rules uniformly 
> for all keys that take a measurement unit
> (e.g. height, width, ele, max_height, etc).
> --
> Parsers are cheap.  Any parser worth using can convert 22m, 22 m, 22 
> feet or a variety of reasonable variants.
> Humans are messy.  Forcing them into boxes generally goes badly.

+1

As much as wish meters were used everywhere, I'd rather make it easier 
for contributors by letting them use whatever make sense to them, and 
worry about unit conversion later. Especially in this case, where 
mechanical conversion is so easy. If the elevation was surveyed in feet, 
entering it in m will almost always result in loss of precision.

For my own maps, such as [1], I use a simple osm2pgsql lua script [2] 
that does various preprocessing, including converting all ele and width 
tags to feet. It's fairly liberal in the formats it accepts for values.

By the way, I thought that the wiki page for ele *used* to say that 
other units than m were acceptable (if explicitly specified) but I may 
be confusing it with something else, like width?

[1] http://toposm.ahlzen.com/hikemap.html
[2] https://github.com/Ahlzen/Hikemap/blob/master/hikemap_tagtransform.lua

- Lars