Am 30.03.2012 11:17, schrieb Paul Norman:
There are a significant number of cities in BC and Washington which have
borders that in practice[1] coincide with the Canada/US border. Currently in
OSM these are represented with many nearly-overlapping ways.
The Canada/US border here consists of the BC-WA border, BC-ID border, BC-MT
border, AB-MT border, SK-MT border, SK-ND border, etc. There are separate
ways for the cities on the Canada side and cities on the US side.
...
This would reduce the number of ways present when you download a section of
the border and have many advantages. The one big disadvantage is that it
would boost the number of ways in the Canada and US relations. This
increases the chance of conflicts and also increases the number of places it
could be broken.
I merged the us/canadian border with the north dakota, minnesota and
montana state borders and also county borders a while ago, and I agree
that there should only be one way for one part of the border, this line
being shared in all affected boundary relations.
I don't really think this will increase conflicts, as if you delete one
way of a border, all affected relations will be notified (at least in
JOSM it's impossible to download a way without downloading all relations
this way is connected.
I did include city boundaries where available, but this was the case
only on one city (Emerson, MB). In Europe, nearly all borders are made
up of individual municipality border stretches (I once loaded italy's
circumference, made up of >2500 ways).
Either way, the Canada/US border will remain very complex with so many
different boundary relations ending there.
If I do this, I will also align the borders to the IBC data (PD). I've
investigated the accuracy of their data, and it agrees with the markers on
the ground to within 10cm. I believe the most significant source of error in
their data is the NAD83 to WGS84 conversion.
[1]: The actual legal situation is much more complicated and serves as a
good example of the problems that arise when you define what is supposed to
be one line in multiple ways. The biggest oddity is that the Washington
border extends out of the United States into Canada. All of the other
oddities are just a few meters at most.
--
cheers,
Alex
_______________________________________________
Talk-us mailing list
[email protected]
http://lists.openstreetmap.org/listinfo/talk-us
