Changeset: 47138016
Fix tagging of some bays by natural=bay: https://wiki.openstreetmap.org/wiki/Tag:natural%3Dbay
Closed by jptolosa
Tags
created_by | JOSM/1.5 (11639 es) |
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source | survey |
Discussion
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Comment from aharvey
These bays have been changed between natural=water and natural=bay many times in their history, unfortuantly most renderers don't yet support natural=bay areas. Even the wiki notes that "they should not be rendered in solid color indicating water themselves".
What's the harm in leaving as natural=water, water=bay until the renders are caught up?
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Comment from aharvey
Let's discuss over at https://lists.openstreetmap.org/pipermail/tagging/2017-March/031856.html.
In the meantime I've reverted this change. You'll see in the history that I tagged this as natural=bay a few years ago and think this is the best way to tag, unfortunately it's a big area and the current advice on the wiki says renders shouldn't render it as water, which breaks maps in a severe way. So I think we should keep it as is until we can resolve that.
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Comment from jptolosa
You're wrong, all renders support natural=bay. This is the approved tag by the community for mapping a bay area. Here you can see an example of a successful rendering: http://overpass-turbo.eu/s/nOQ
Obviously, to obtain a correct render, the polygon should be inside a water polygon or in the ocean. In the past you tagging it as natural=bay, but you remove natural=coastline also. natural=coastline should not been removed from maritime waters. This is the reason of a deficient rendering. More info here: https://wiki.openstreetmap.org/wiki/Tag:natural%3Dbay#How_to_map -
Comment from aharvey
Thank you, I can see that makes sense, the bay area should either be within the ocean or some other waterbody like a lake, river, etc. So the blue water rendering would come from the waterbody or ocean and the natural=bay area is there to label the area.
I disagree with tagging the insides here as coastline as it doesn't match the description of natural=coastline on the wiki.
In my view the solution here to remove the coastline tag from the inside of the bay and work out what kind of waterbody it is and tag it as that. Perhaps riverbank will work?
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Comment from jptolosa
According the description of natural=coastline it should be placed exactly in the mean high water spring i.e. IMO more or less here: https://www.openstreetmap.org/#map=15/-33.9765/151.0237
Is better to solve the "conflict" consulting the different sources about this topic.
Check the concept of "ria": https://en.wikipedia.org/wiki/Ria
Article of Botany Bay is also usefull that cite a paper about the marine condition of the bay: https://en.wikipedia.org/wiki/Botany_Bay
We can review different sources about the topic to decide the best placement of natural=coastline. In the mailing list somebody posted this paper that show us a clearly sea water dominant in the estuary: http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.575.3453&rep=rep1&type=pdf
Regards. -
Comment from jptolosa
Furthermore, note that in the description of natural=bay you can read the next text: "The edge of a bay towards land should coincide with the coastline" in the section 'how to map'.
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Comment from jptolosa
But technically the wiki doesn't prohibit the usage of waterway=riverbank into the sea. Then, if the sources doesn't convince you, we can use both tagging: natural=coastline & waterway=riverbank + tidal=yes
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Comment from aharvey
This is going to be an uphill battle , so I'm going to pivot and look into using something like coastline=pelagic from wikipedia "A pelagic coast refers to a coast which fronts the open ocean, as opposed to a more sheltered coast in a gulf or bay." on the oceanic coastline because I need separation of these shorelines within these bays and the coastline facing the ocean. Combined with creating my own sea/ocean polygon which excludes rias. I'd like OSM to be able to differentiate between a sea/ocean (excluding rias) and flooded rias such as Botany Bay. I thought the natural=coastline tag would provide the sea/ocean polygon, but I guess not since I don't consider Woolooware Bay the sea, as people wouldn't say you're at sea or in the ocean when in that bay, I'll continue this discussion on the list to work out the best way to tag rias.
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Comment from jptolosa
Definition of the natural=coastline is independent of locally established divisions. boundary=* tag supplies the second purpose. Your point view is incompatible with the OSM basic principle "Map what's on the ground".
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Comment from aharvey
Exactly, I'm trying to ensure the natural=coastline tag and other tags are reflecting the natural environment on the ground based on my ground surveys of the area.
As I mentioned on the tagging thread for me, based on on the ground surveys and local knowledge Botany Bay (http://www.openstreetmap.org/relation/1214649)
isn't part of the open ocean but Bondi Bay
(http://www.openstreetmap.org/node/926183187) is, and I'd like OSM to be able to distinguish the two cases.Just the same way as the internal shoreline of Botany Bay is different to the coastline along Bondi Beach, your proposed tags don't offer any way to differentiate these different shorelines/coastlines.
Tagging rias and pelagic coastlines may prove to offer some way to do this.
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Comment from jptolosa
Of course, is interesting to differentiate the type of a coastline. Unfortunately there are no a tag for this purpose yet. The tag natural=coastline is only used to mark mean high water spring and it doesn't capable to differentiate the type of seawater. We can create a new tag based on your ground observations.
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