[Tagging] Feature Proposal - RFC - Survey Markers

[Paul Allen]

On Fri, 4 Jun 2021 at 06:09, Kyle Hensel <K.y.l.e at outlook.co.nz> wrote:


> I’m not too sure about the mapping of destroyed features in OSM...
>

In general, we do not map things where no physical trace remains.  But
there are exceptions (and some people who take exception to some of
those exceptions).

>
>
> But there seem to be exceptions to this, so I think someone else needs to
> answer
>
this question.
>

The problem comes where armchair mappers are likely to resurrect features.

The organization "Geograph" exists to collate representative images of
every square kilometer of the British Isles.  Survey marks are popular.
Here's
a link to a very small fraction of them:
https://www.geograph.org.uk/tagged/OS+trig+point
One of those images is of the remains of a pillar: it's no longer usable for
surveying but can be used to help locate oneself.  Others may have been
removed completely but live on in collections like this and are still
visible on
current aerial imagery.

For markers that no longer exist, a lifecycle prefix such as removed,
demolished,
razed or destroyed should be applied to man_made=survey_point to help
preventing their return as zombies.  It is debatable whether it should also
have
was:survey_point:structure=*, or just survey_point:structure=*,  or not
have the
structure tagged at all.

For unusable remains there are opposing points of view as to how to
handle them.  I'd tag them as though they were functional and add
ruins=yes (on many cartos that means they will render but data
consumers can tell they are not usable survey points).  Cue a long,
drawn-out argument about this.  I'll get my response in early and
say it's not wrong to tag it that way rather than with a lifecycle
prefix and people are free to tag it however they like.

BTW, you proposal might benefit if you work through Geograph's
tagging categories for survey marks as you'll find things like
https://www.geograph.org.uk/photo/6791444

-- 
Paul
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