[Tagging] Feature Proposal - RFC - Survey Markers

Kyle Hensel K.y.l.e at outlook.co.nz
Sat Jun 5 06:24:01 UTC 2021

Hi all,

I was hesitant to propose a tag for destroyed survey markers , but since there seems to be support for mapping them, I think the discussion needs to shift to how to tag them.

Some of the suggestions:

1. survey_point:condition=destroyed
2. former:man_made=survey_point (or a similar lifecycle prefix)

I think the first option is better since a 'destroyed' survey marker is still a valid survey point - Michael has explained this well in an earlier message: https://lists.openstreetmap.org/pipermail/tagging/2021-June/061700.html


To address some other comments:

> “I would therefore propose a survey_point:structure=moved”

I proposed survey_point:condition=not_reliable for this purpose – if the location is known to be incorrect because it was moved.
This way you can still tag the structure of the marker.

> “BTW, you[r] proposal might benefit if you work through Geograph's tagging categories for survey marks [...]”

Thanks for that info, I think we now need some new survey_point:structure values:

underground - https://berntsen.com/Surveying/Specialty-Markers/DEEP1-Magnets-for-Surveys
wall - https://www.geograph.org.uk/photo/6791444

> “Let's use survey_point:structure=ground instead of survey_point:structure=none”

(feedback from https://wiki.osm.org/Talk:Proposed_features/Survey_Markers)

I can see the logic in this argument, do others on this mailing list have an opinion?
Maybe it should be survey_point:structure=pin instead of 'ground' or 'none'

From: Anne-Karoline Distel<mailto:annekadistel at web.de>
Sent: Saturday, 5 June 2021 09:27
To: tagging at openstreetmap.org<mailto:tagging at openstreetmap.org>
Subject: Re: [Tagging] Feature Proposal - RFC - Survey Markers

I have surveyed about 300 benchmarks (crowsfeet) in Ireland which are on old Ordnance survey maps, but i only add those where I can confirm the location, of course. These benchmarks were chiselled into existing structures, mostly walls and bridges, but sometimes milestones or just large stones in a field (very few of those left). However, some have clearly been moved which is recognisable by the stone having been rotated by 90 or 180° or being on the wrong side of a wall or gatepost in comparison to the old maps. I would therefore propose a survey_point:structure=moved rather than survey_point:structure=none to indicate that the survey point is no longer in its original position. I usually left a note or used moved=yes already. I haven't always checked against older maps, though, in cases where I didn't go looking for them and just found them.

http://overpass-turbo.eu/?q=LyoKVGhpcyBoYcSGYmVlbiBnxI1lcmF0ZWQgYnkgdGhlIG92xJJwxIlzLXR1cmJvIHdpemFyZC7EgsSdxJ9yaWdpbmFsIHNlxLBjaMSsxIk6CsOiwoDCnMSLbsWCbcSwaz15ZcSGxLogSXJlbGFuZMWIwp0KKi8KW291dDpqc29uXVt0aW1lxaXFpzI1XTsKLy8gZmV0xYIgxLDFgCDFiMKcxZfFmcWbxZ3CgMKdxJvEq8S_xYHFg8S6Cnt7xJBvY29kZUHFmGE6xofFmsWcfX0tPi7Gj3LFgsacxYDFuMW6xI_ElMSdciDFmHN1bHRzCigKICDGrnF1xJLEmsSjcnTFvG9yOsaExYnFi8WNxY_FkcWTxZ7GvCBud3JbIseNaMWOcmsiPSLFknMiXSjGgmHGp8WAxqloxqthKcW4x6_FucW7cMS3bseGxrTGtsa4CsWzxJjGmXnFuD7FuMe8c2vFmSBxdDs&c=BG7fzs-JkI&R (don't know why it doesn't give me the short link)

Well done on the proposal!

On 04/06/2021 05:58, Kyle Hensel wrote:
Hi, thanks for the feedback

I agree if the survey point still exists but just the structure has been removed, then this proposal would suggest updating the tags from `survey_point:structure=(whatever) ` to ` survey_point:structure=none`

> If you remove the point because it is no longer easily visible

That’s not what’s suggested – if a survey marker still exists but is not easily visible, the proposal is to tag it as `survey_point:condition=not_visible`

So this:


Is totally fine to map.

I was just proposing that if neither the survey point nor the structure exists anymore, then it should be removed from OSM.
This would only happen if a natural disaster or man_made earthworks removed all traces of it... do you think this is logical?

My rationale for suggesting this, is that OSM shouldn’t be used to map historical, non-existent things according to:

From: Michael Patrick<mailto:geodesy99 at gmail.com>
Sent: Friday, 4 June 2021 16:27
To: tagging at openstreetmap.org<mailto:tagging at openstreetmap.org>
Subject: Re: [Tagging] Feature Proposal - RFC - Survey Markers

> > survey_point:condition=destroyed is not proposed. If the survey marker no longer exists, it should be deleted from OSM.

The survey point and observable evidence still exist, even though the monument may no longer be present. Monuments are 'lost' and 'recovered' all the time because of all sorts of events - vandalism, crime, natural disasters, land slips, forestry activity, etc.
There is a whole domain of archeological survey forensics, with techniques such as discontinuities in soil, presence of rust particles, dissecting trees to find blazes, and even collecting oral histories.
If you remove the point because it is no longer easily visible, then you are also obligated to remove many of the intermediary points that define the polylines of a lot of admin and park boundaries - those once had markers also ( especially near rivers ) and are now missing.

Michael Patrick


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