[Tagging] Additional sub tags for survey mark

Mark Wagner mark+osm at carnildo.com
Tue Nov 21 09:32:12 UTC 2017


On Tue, 21 Nov 2017 10:47:30 +1100
Warin <61sundowner at gmail.com> wrote:

> Hi,
> 
> There have been attempts in the past to add sub tags to 
> man_made=survey_point 
> https://wiki.openstreetmap.org/wiki/Tag:man_made%3Dsurvey_point
> 
> To me there are 2 'types'. they are quite different;
> 
> Triangulation (or 'trig point') that are visible over quite some
> distance (say over 2 km), used to triangulate a position without
> having to go to the mark. Usually a pole standing on top of a
> rise/hill.
> 
> Benchmarks that are visible on the surface but cannot be sighted at
> any distance. They can be small brass plaques fastened to the ground
> or engraved into stone. These are used by surveyors by placing a
> tripod over the mark, thus have to be locally approached.
> 
> If consideration is given to
> https://wiki.openstreetmap.org/wiki/Seamarks/Categories_of_Objects#Control_Points_.28CATCTR.29
> 
> then expanding survey_point in a similar manner could be
> 
> survey_point:configuration=triangulation/benchmark
> 
> I use 'configuration' rather then 'type' or 'category' as it is more
> specific as to what is meant.
> 
> Any thoughts?
> Are there any other configurations?

Survey marks in the US tend to come in three types:

1) Benchmarks, which are typically a bronze disk solidly attached to
the top of something.  Both the horizontal and vertical positions are
usually well-surveyed.
2) Vertical control points, which are typically a bronze disk affixed
to the side of something.  The vertical position is well-surveyed, but
the horizontal position is only recorded well enough to let a surveyor
find it.
3) Reference marks.  Typically, a bronze disk attached to something
that gives directions to a nearby survey mark.  The position isn't
recorded beyond what's needed to find it, if that.

(There are also horizontal control points, but these tend to be things
like flagpoles and smokestacks which have been surveyed and documented
for use as survey marks.)

-- 
Mark



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