[Talk-ca] Maritime Boundary

David E. Nelson denelson83 at yahoo.ca
Mon Jan 13 04:24:25 UTC 2014


It seems to me that the provincial boundary should be displaced from the coast of the Island of Newfoundland by 3 NM.  Is there a tool one can use to do that?

 
- David E. Nelson



On Sunday, January 12, 2014 8:00:21 PM, Richard Weait <richard at weait.com> wrote:
 
On Sun, Jan 12, 2014 at 9:05 PM, Adam Martin <s.adam.martin at gmail.com> wrote:
> Hello!

> Is this supposed to be the actual maritime boundary? I don't think it is -
> the parts of the line appears to be for the Provincial boundary. If it is
> the Provincial boundary, shouldn't it follow the coastal boundary?
>
> If I am mistaken, let me know.

I don't think that you are mistaken, but I don't think you have all of
the facts either.

The 12NM line does look to be one that was created automatically.  It
certainly wasn't surveyed by a local mapper.  :-)  Same for the inland
"maritime boundary".  I looked at that one in more detail.  Here's
what I see going on.

The boundary way is this one

http://www.openstreetmap.org/way/30114485

It is also part of two relations.  One relation is a civil boundary,
the other is an administrative (provincial)

Boundary ways can not be understood fully, or edited wisely, without
understanding relations.  I wouldn't edit any complex form, such as a
boundary relation, with an editor other than JOSM.  And not with any
editor, on a mobile device.

Today, the way appears badly drawn, and incomplete in tagging.  I'll
take a few guesses at why.

The history of that way shows 28 revisions.  The first one was the
creation of the way, as an import from geobase in 2009. It was tagged
as an administrative boundary (not a maritime boundary).  Likely, this
was the best data available to us at the time.  With the currently
available imagery, we can see that the imported boundary does not
align with imagery, nor does it reflect some of the details in the
current imagery.

Revisions 2 through 25 have been redacted, due to edits by users who
did not agree to the license change.  The boundary may have had some
improvements and corrections through those edits.  Improved or
otherwise, those edits are gone.

Revision 26 shows that the redaction bot cleaned out the data that we
were no longer entitled to keep.  That left the way without tags.

R27 in 2012 appears not to have directly affected the way. It may have
edited an intersecting way?  It was a large changeset.

R28 in 2013 added the maritime tag you report. The maritime tag alone,
is an unusual form.  I don't think that it would be considered
complete, unless combined with the tags of the parent relations.

When compared with the 'bot-drawn 12nm maritime boundary, this way
appears to be incorrect.  It just doesn't seem to be far enough
offshore to be a maritime boundary.

When compared to http://www.openstreetmap.org/way/115038287 (from
2011, and a canvec import) the '485 way appears "low resolution and
poorly aligned".

So there are are multiple imported boundaries here.  Each were the
probably best available at the time.  Neither are perfect, and now the
appear to somewhat duplicate each other, given the parent relations of
'485.

Hope that helps a bit.


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