2016-02-17 22:05 GMT+01:00 Marc Zoutendijk <marczoutend...@mac.com>: > Generally, when the definitions in OSM are different from what a person > speaking the language might expect, it doesn't work. The issue here: > "small" "a few meters high" seems not pertinent for radio masts which are > among the tallest man made structures on earth, particularly when made of > concrete or steel they can be hundreds of meters high. A quick image search > confirms this (no small structures at all had been found) > > > I was talking about a mast, not about towers. > The wiki (how “unlucky" it may be) is clear on the difference between a > mast and a tower. [1] >
> [1] http://wiki.openstreetmap.org/wiki/Tag:man_made%3Dmast > <http://wiki.openstreetmap.org/wiki/Tag:man_made=mast> > really, this is what I was writing about. You have asked, so here we go: it does define some arbitrary rules that don't fit within the general meaning of mast (as a mast can be very large, indeed the biggest masts are bigger than the biggest towers) by saying they must be small. Then, it contradicts itself by giving examples like this one: http://wiki.openstreetmap.org/wiki/File:Mobile_communications_mast.JPG (declaring it as a mast, and indicating the height as 40m +), and this one: http://wiki.openstreetmap.org/wiki/File:Greifswald_Funkturm_Hans-Beimler-Stra%C3%9Fe_July-2010_SL274692.JPG (although requiring "platforms" in the text this is given as an example for a tower). I do partly agree with the classification of the given examples, and I believe the textual definitions are insufficient and partly "wrong"/not well chosen, and the text contradicts the pictures. There is also an inconsistency in that there now seems to be a man_made=communications_tower as an alternative to the man_made=tower tower:type=communication but the examples for tower and communications_tower should be inverted (because the tower example is clearly a pure communications tower, while the com tower example is clearly a tower that has other purposes aside from the communication function it also serves, e.g. it is a viewing platform (with a cafe that rotates inside the sphere: takes roughly 30m for one turn) and had a clear political message / representation function in 1970 when it was opened (going from memory, figures could be slightly different). Also there are tag suggestions I believe should be removed, e.g. "communication:bos" which is a mash up of English and German (BOS= Behörden, Ordnung, Sicherheit, a German abbreviation for emergency radio). Using tower:type on masts is a bit strange, but could be accepted (it is simplifying the work of the data users). man_made=communications_tower together with tower:type=communication seems an odd recommendation, because it is clearly redundant. Also I miss a statement on the mast page that the whole mast can be an antenna itself (right now it is only stated that it can "hold" an antenna). In osm there is also man_made=antenna and maybe this is the preferred tag in this case, still something should be written about this on the mast page. proposing "communication:microwave" for microwave_links seems to be orthogonal to the intended type of communication (the German word "Richtfunk" added there to the English version indeed describes links of any wavelength and is not a translation of "microwave"). It is also odd in this list of communication subtags (here without prefix): radio television mobile_phone microwave (or are these communication features for microwave ovens?). I don't think there is a reasonable system if we make a typological and functional distinction for masts and towers but then introduce another toplevel category (man_made=communications_tower) for "Really big communications towers >= 100 m". In this system, a tower with any height but without any communication function would get the tower tag, like a communication tower with a height of 99 m, but a tower with 101 m and some antenna would get a completely different tag? How should I tag an office tower with some antenna on top, communications tower if it's more than 100m? Basically the mast page seems to be a collection of stuff people have put there, without broader discussion I believe, because otherwise the inconsistencies and contradictions of this page with other osm feature definitions and pages would have come to light earlier. > > From a mast I'd expect to have guy wires, while a tower should typically > be freestanding, so the word "small tower" doesn't seem to be a lucky > choice either. > > > I don’t expect guy wires, neither does the wiki, nor have I ever seen them > in use for all (55 or so) man_made=mast structures that are in my > neighbourhood (in the Nehterlands). Typically “small” masts of steel or > concrete and about 5 - 15 meters high. > yes, you often won't have guy wires for structures between 5 and 15 meters of height > But that was not my question in the first place, I asked for the use of: > > man_made=mast > mast=lighting > > or > mast:type=lighting > > I'm fine with this usage of mast. Or call it a "lighting_mast" right away, no need to subtype (at least not at this functional level). I also prefer the "mast:type" tag over the tower:type tag for a mast, and it is already used in few numbers (including lighting value): http://taginfo.osm.org/keys/mast%3Atype#values Cheers, Martin
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