On 23 November 2017 14:37:53 GMT+00:00, Craig Wallace <craigw84+...@gmail.com> wrote: >On 2017-11-20 23:47, Warin 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? >It would be useful to tag the physical style of the survey point. ie >the >size and shape and what it is made of. Is it a pillar, or just a metal > >plate or bolt on the ground. This would tell you whether it is an >obvious landmark or not. > >Tagging what the survey point is used for is a separate thing. ie >triangulation, or a benchmark. Nowadays most trig points are redundant, > >so they are not actually used for any sort of survey work. Though in >the >UK there are some still maintained as "passive stations", plus a few >"active stations" (with a GPS receiver). >Note there are some "Fundamental Benchmarks", which are a small stone >pillar. > >Some of the common types in the UK: http://trigpointing.uk/wiki/Types >
Trig points are an important feature in UK outdoor circles, particularly in mountain and moorland areas. They are places you head to and obviously give a precise reference as to where you are. Some have been adopted by groups who maintain them for future generations. They also provide a good place to sit and watch the world below, my OSM username is no accident. Phil (trigpoint) -- Sent from my Android device with K-9 Mail. Please excuse my brevity. _______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
