[Tagging] Feature Proposal – RFC – natural=peninsula (Was: Feature Proposal – RFC – place=peninsula)

Dave Swarthout daveswarthout at gmail.com
Thu Jan 10 08:52:55 UTC 2019


We just went through a whole discussion about mapping bays as
polygons. (see https://lists.openstreetmap.org/pipermail/tagging/2018-November/040911.html)
This is a similar one. I was one of the people who promoted converting
nodes that describe bays into polygons in order to better represent
their true size and provide better label placement. Now, after having
to add boundaries to those areas of coastline, I can see the benefits
of leaving the nodes as they are and allowing software to place the
result labels as best it can. Many on this list didn't favor using
multipolygons to outline bays either. Involving polygons does
complicate subsequent mapping chores. For example, I was adding a
National Park boundary in Alaska. I wanted to conflate it with
coastline where I could. So I have this way, the boundary way, that is
also shared with a peninsula, and also a portion of named ocean, the
Chukchi Sea, a large "bay" of sorts, which is also a multipolygon.
Each section of coastline/boundary must now be added separately to
these three multipolygons! It's a ton of work.

I stopped using multipolygons to map bays after that. I might use them
on occasion to better "illustrate" peninsulas but I won't do that in
an area where there's already multipolygon complexity present. As
people pointed out in the last discussion, it makes for a ton of extra
work and invites errors from novice mappers. I now agree with that


On Thu, Jan 10, 2019 at 2:56 PM Tomas Straupis <tomasstraupis at gmail.com> wrote:
> 2019-01-10, kt, 09:06 Martin Koppenhoefer rašė:
> > coding the geometry into the db does not necessarily mean creating polygons though.
> > You could also store just 3 nodes and a hint that these are representing a polygon, to store a triangle (for example).
>   Sorry, I did not get it. How saving only vertexes is better than
> having a polygon (made out of those vertexes)?
>   Full geometry is required to be able to calculate label positions on
> all scales. For small scales this could be a simple curved line
> (calculated from polygon geometry), for large scales it could be a lot
> of labels placed/scattered on the same polygon geometry and
> approximating (simplifying) such polygon too much would decrease
> number of labels placed or labels would be placed outside of an object
> which is even worse.
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Dave Swarthout
Homer, Alaska
Chiang Mai, Thailand
Travel Blog at http://dswarthout.blogspot.com

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