On Thu, Sep 6, 2018 at 6:38 PM François Lacombe <fl.infosrese...@gmail.com> wrote: > To me, waterway=* should only get values to map linear water courses for the > routable hydrographic network. > Newer tagging with natural=water sounds ok, except for artificial water > features. > I'm not so keen of natural=water over a man made irrigation canal, unless > there is no artificial water, even in artificial man made structures
natural=* is a lost cause, and part of the issue there is that there are a good many natural=* tags that don't have neutral equivalents. There does need to be some way to say, "this land is covered by water perennially" without asserting who put it there. It's much worse when it's 'this land is covered by trees.' There is no non-controversial tag to assert that simple fact. As soon as we start in with the idea that a reservoir is 'unnatural' water, we give trouble for initial mapping. I can't necessarily see on aerials whether the pond that I see has a dam at its outlet, or whether the dam was put there by humans or beavers, or whether the dam is creating a new impoundment or merely inducing an insignificant rise in the water level of an already-existing waterbody. If a mapper can't say, 'there's water here', 'there are trees here', 'there is grass here' without doing research on human intent and purpose for the landcover, navigability of the waterways, there's something wrong with the data model. Those are the bones that everything else fleshes out. In some of the places I map, there are still broad expanses of blank areas on the map, where the road network is hallucinatory, even fairly major watercourses are missing, and geomorphology is virtually nonexistent. I need a way to sketch in broad strokes without either telling lies or having to do research before I even start. The idea that waterway=* must be routable is, frankly, a new one to me. How is a mapper supposed to tag a non-navigable river? Water routing sounds like an intriguing idea, but at least so far, tagging doesn't appear to support it. To be more specific: I don't want to stand in the way of that sort of project by mismapping things, but I frankly don't know how to get it right. I recently mapped my first river multipolygon (needed it for a large-scale map that I was rendering), It is most emphatically NOT navigable, but I added the polygons because it's fairly wide and I wouldn't fancy fording it in a season of high water. I'll plead guilty to stopping at, 'induces no warnings in JOSM, and renders correctly on OSM and in my custom rendering.' I used waterway=riverbank and a multipolygon, because that appears to be what others used nearby, and I did indeed try to approximate the Thalweg with waterway=river. In any case, it would be a very quick thing to change that particular multipolygon to natural=water water=river. How *ought* the Thalweg be tagged? That particular river drains into a reservoir. At least *some* of its land area is 'natural' water; there are drowned ponds under there (whose shorelines could be researched; I have maps from a 1903 survey). But recovering their shorelines hardly seems urgent to me. Can we agree on some sort of tagging for, 'this is a waterbody'? That's more observable than, 'this is something Mother Nature put here' as opposed to 'this is something crafted by the hand of humanity.' _______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
