landform promontory

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landform promontory

Warin
Hi,

There is not a tag for the land form 'promontory' meaning a raised mass
of land projecting into a low land or water body.

See https://en.wikipedia.org/wiki/Promontory

I have come across them as named 'points' and have been tagging a few of
them as place=locality for lack of something better.


The nearest thing is natural=cape, but that only applies to sea
retaliated things and I don't like the key 'natural' as it applies to
both 'natural' and 'unnatural' thing making a nonsense of the word.


So I think the best tag would be landform=promontory.


Other ideas?



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Re: landform promontory

Joseph Eisenberg
Where are these features located? I haven't seen anything called a "promontory" in the western USA: we would call these features ridges or cliffs if they are hills or mountains above lower land, or if they are surrounded by water they would be a headland, peninsula, cape, or "point".

In OSM, there is already a tag for natural=cape, and the wiki page suggests it can be used for all water promontories:
"Cape - a prominent, elevated piece of land sticking out into the sea or large lake. Includes capes, heads, headlands, peninsulas and (water) promontories."

"Natural=*" is perfect in this case, because headlands/capes are natural features formed by geological processes and natural erosion. 
So if you are tagging "promontories" that project into a lake or sea, then use natural=cape on a point.

If you are tagging hills or mountains on land, use natural=ridge as a way along the center of the ridge in most cases. 
You can also add natural=peak  to a node, if there is a local high point that is named.
"Natural=*" is also totally appropriate in this case; ridges and peaks are also formed by natural geological and meteorological processes, no?

I've been meaning to ask the folks at OpenStreetMap Carto to start rendering the names of ridges as a name label, so that mappers will not be tempted to add place=locality or natural=peak when the named feature is really a ridge.

Thanks!
Joseph



On Thu, Oct 4, 2018 at 8:20 AM Warin <[hidden email]> wrote:
Hi,

There is not a tag for the land form 'promontory' meaning a raised mass
of land projecting into a low land or water body.

See https://en.wikipedia.org/wiki/Promontory

I have come across them as named 'points' and have been tagging a few of
them as place=locality for lack of something better.


The nearest thing is natural=cape, but that only applies to sea
retaliated things and I don't like the key 'natural' as it applies to
both 'natural' and 'unnatural' thing making a nonsense of the word.


So I think the best tag would be landform=promontory.


Other ideas?



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Re: landform promontory

Warin
On 04/10/18 09:40, Joseph Eisenberg wrote:
Where are these features located?

Inland. Not near the sea.

For the same reason you would not tag a cape as a ridge or a peak you would not tag a promontory as a ridge or a peak.

Not all ridges end as a promontory - some have gradual slopes. Not all promontory are a peak, they may have a line at about the same height leading away from them.

They are named as 'point' here but the closest in wikipedia I could find is promontory. So I used that term.

Sample?
Node 5946074161 https://www.openstreetmap.org/node/5946074161
node 5950099862 https://www.openstreetmap.org/node/5950099862#map=19/-33.59309/150.55939 This does have a named ridge leading to it
https://www.openstreetmap.org/way/630058012

Perhaps 'cape' should be dropped in favour of
promontory as that could be used for both land and sea? :)

I haven't seen anything called a "promontory" in the western USA: we would call these features ridges or cliffs if they are hills or mountains above lower land, or if they are surrounded by water they would be a headland, peninsula, cape, or "point".

In OSM, there is already a tag for natural=cape, and the wiki page suggests it can be used for all water promontories:
"Cape - a prominent, elevated piece of land sticking out into the sea or large lake. Includes capes, heads, headlands, peninsulas and (water) promontories."

"Natural=*" is perfect in this case, because headlands/capes are natural features formed by geological processes and natural erosion. 
So if you are tagging "promontories" that project into a lake or sea, then use natural=cape on a point.

If you are tagging hills or mountains on land, use natural=ridge as a way along the center of the ridge in most cases. 
You can also add natural=peak  to a node, if there is a local high point that is named.
"Natural=*" is also totally appropriate in this case; ridges and peaks are also formed by natural geological and meteorological processes, no?

I've been meaning to ask the folks at OpenStreetMap Carto to start rendering the names of ridges as a name label, so that mappers will not be tempted to add place=locality or natural=peak when the named feature is really a ridge.

Thanks!
Joseph



On Thu, Oct 4, 2018 at 8:20 AM Warin <[hidden email]> wrote:
Hi,

There is not a tag for the land form 'promontory' meaning a raised mass
of land projecting into a low land or water body.

See https://en.wikipedia.org/wiki/Promontory

I have come across them as named 'points' and have been tagging a few of
them as place=locality for lack of something better.


The nearest thing is natural=cape, but that only applies to sea
retaliated things and I don't like the key 'natural' as it applies to
both 'natural' and 'unnatural' thing making a nonsense of the word.


So I think the best tag would be landform=promontory.


Other ideas?



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Re: landform promontory

Andrew Harvey-3
On Thu, 4 Oct 2018 at 10:43, Warin <[hidden email]> wrote:
> Perhaps 'cape' should be dropped in favour of promontory as that could be used for both land and sea? :)

Water based promontories should stay as natural=cape as per the wiki
they are "prominent, elevated piece of land sticking out into the sea
or large lake", if we want we can add a subtag
cape=point|head|promontory... but to be honest most of the time the
name will give this away already.

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Re: landform promontory

Joseph Eisenberg
In reply to this post by Warin
>>Where are these features located?
>Inland. Not near the sea.
>Not all ridges end as a promontory - some have gradual slopes. Not all promontory are a peak, they may have a line at about the same height leading away from them.
>They are named as 'point' here but the closest in wikipedia I could find is promontory. So I used that term.

Interesting. So this is a "node" on a ridge which doesn't qualify as a summit because it's topographic prominence is zero (it isn't the highest point, even locally). But it looks kind of like a pointy peak from the low ground around it, and therefore has a local toponym. 

I actually think there are a number of named features currently tagged natural=peak which are really points or promontories by this definition. Eg: https://www.opentopomap.org/#map=14/51.82578/10.68691 vs https://www.openstreetmap.org/#map=14/51.82578/10.68691

It would be nice to have a more precise tag, so that mappers would not mis-tag named points of hills or ridges as peaks when they are not actually a summit. Place=locality doesn't give any that it is a geological feature. 

I would personally use natural=*, because it fits with all the similar features: natural=ridge, natural=peak, natural=volcano, natural=cliff, natural=valley etc.

It would be somewhat ambiguous to use natural=promontory, because as wikipedia says, this could be a headland or cape, as well as an inland point or promontory above a valley. Natural=point could also work. However, if you document the tag with a short wiki page (proposal) that would be enough to avoid confusion, and we could also put a note on the natural=cape wiki page warning against mistagging with natural=point or =promontory.

-Joseph

Perhaps 'cape' should be dropped in favour of promontory as that could be used for both land and sea? :)

PS: ha ha :-)


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