[Tagging] Using multipolygons to map bays in Alaska

Paul Allen pla16021 at gmail.com
Sat Nov 17 20:35:21 UTC 2018


On Sat, Nov 17, 2018 at 7:09 PM Frederik Ramm <frederik at remote.org> wrote:

>
> My argument was that if you can get away with using a single node for
> labelling, then you don't have to burden all those 1,400 coastline ways
> with one (or two or three) extra relation memberships and that would be
> preferable.
>

I agree entirely with that sentiment, because I'm lazy (but I dress it up
by telling people that I
work smarter, not harder).  If you can get the exact same result by two
different methods and one
of those methods requires a lot less work than the other, then of course
you should go for the
one that is less work.

But it's rarely the exact same result when dealing with bays, as Kevin
(amongst others) has
pointed out.  The node and area give different results in some
circumstances and could, given
improvements in rendering, give even greater differences in their output in
the future.

You point out that neither a new polygon that shares nodes with coastline
ways nor a complex
relationship are going to play nicely with the toolchain.  Being a bear of
little brain, and lazy to
boot, my first thought would be a crude polygon approximating the
coastline.  It would have few
enough nodes that it would be renderable but approximate the coastline
sufficiently well for label
placement.  Provided the carto didn't render the bay in a different colour
or with a visible border it
would handle label placement nicely (particularly if the renderer's
placement algorithms
improved in the future) without looking fugly.  I must be wrong about this,
though, because I
recall an earlier post in this thread pointing out where somebody had done
something very like
that and denounced it as a crime against humanity.

So all that appears to leave is a node with sub-tags of bay=small,
bay=intermediate, bay=large and
bay=supersize to control the size of the label whilst the mapper controls
the position of the label by
guessing where the node ought to go.  I still like a polygon even if the
water in the bay looks no
different from the ocean because using the query tool on the polygon will
bring up an approximation
to the extent of the bay.

-- 
Paul
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