On Tue, 21 Nov 2017 10:47:30 +1100 Warin <61sundow...@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 _______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
