[Tagging] Using multipolygons to map bays in Alaska

Kevin Kenny kevin.b.kenny at gmail.com
Sat Nov 17 18:36:59 UTC 2018


On Sat, Nov 17, 2018 at 6:29 AM Frederik Ramm <frederik at remote.org> wrote:

> Another pet peeve of mine is a dislike of what I call "relation mania",
> where we have land boundaries that can easily be part of 20 different
> relations on different admin levels and other boundary types. It's bad
> enough on land, and makes editing harder for everyone;
>

You're welcome to this particular opinion in your personal capacity and are
free to argue the point as passionately as you care to.

When you have your DWG hat on, might I ask you to acknowledge that there is
a diversity of opinion in the community on this topic? A minority of users
(including myself), whose number appears to be growing, find that sharing
boundary ways among multipolygons creates a structure that actually is
easier to enter, edit and maintain than the one that appears from multiple
retraced ways over the same nodes, or worse, independently traced ways that
are approximating the same boundary in the field. Land use, land cover, and
cadastral boundaries (such as administrative regions) in particular appear
to be well served by this sort of topological approach.

Today, the difficulty seems to depend partly on the editor in use. JOSM and
Meerkartor handle it quite well indeed; iD and Potlatch still struggle -
and that may be part of the reason behind the "it makes editing harder"
argument. (There's a chicken-and-egg situation there too: some  edittors
support it badly, so people argue that it shouldn't be done, so those
editors continue to support it badly.) If the idea becomes more relevant,
the tools will improve.

Given that there is some history of arbitrary decisions in this particular
arena, may I make the plea in advance that the technique not be summarily
suppressed until there is more experience with how it works out in the
places where it's being tried? I know you've managed to exercise such
restraint in the past; you've personally disagreed with at least one import
that I've conducted and nevertheless allowed it to stand.

This request also has nothing to do with relations that are large enough to
break the tools. I'm confining my request here to features that are
relatively small in extent - perhaps up to a few tens of km on a side. The
larger of them would be represented as multipolygons in any case because
their bounding ways have too many nodes to be handled gracefully.
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