[Talk-ca] Merging ways

[Adam Dunn]

There's two methods to join two areas: you can delete the coincident
segments and combine the two unclosed polygons (as you have tried), or
you can use JOSM's "join ways" feature.

What you are doing (the first method) should have worked, and I don't
know why the two ways "don't want to stay joined together". Make sure
that the two ways are open, and that their coincident nodes are merged
together (highlight them both and click 'm' on the keyboard for
merge). Then select both ways and 'c' on keyboard for combine. You
will get a "tag conflict" window that allows you to select which tags
should apply to the final way, as well as which member of the relation
should be kept or removed. In this case you will want to delete the
tags on the way (since the relation will have the tags you need), and
you will want to keep the member in the relation.

For the second way (faster and less involved), you need to 'm'erge all
coincident nodes, and make sure there aren't any nodes that are part
of only one way or another (all coincident nodes have to be part of
*both* ways). Since the coincident nodes in the middle of the lake
will disappear when the areas are merged, you can just delete them
without worrying about merging. Then select both ways and type
'shift-j' for "join areas". Deal with the tag conflicts (again, you
won't need tags on the way because the tags are in the relation), and
you should be done. "Shift-j"oining areas will handle two ways, a way
and relation, or two relations, just as long as they are well formed
(nodes are merged properly ahead of time and all of the ways are
closed polygons [this won't work where ways have been split at 2000
nodes, since those ways are open polygons and josm won't know how to
merge the two areas]). I demonstrate this technique in
[http://www.youtube.com/watch?v=OJr_gucFGMY#t=3m45s]

Also don't forget to copy over the name of the lake, since Canvec
doesn't appear to have the name.

Adam

On Sat, Aug 20, 2011 at 10:15 PM, James Ewen <ve6srv at gmail.com> wrote:
> Okay, how do I accomplish this task?
>
> I drew the outline of Wolf Lake by hand quite a while ago. I also
> imported the water features from CanVec as well. Now there are three
> ways defining the lake. One is the way that I drew by hand. The second
> is one imported from Canvec which is a simple outline with the tag
> natural:water. The other half of the lake (split across a CanVec tile
> boundary) is a multipolygon outer relation because there's an island
> in the lake. I have tried removing the ways that define the split in
> the tile, and join the two remaining halves. I can't do that because
> there's a tag conflict. I removed the tags from the natural:water
> side, and tried to join the remaining untagged way to the outer
> relation, but it does not want to stay joined together. One would
> think that you should be able to simply join the untagged way to the
> way defining the outer relation, completing the circular way.
>
> This should be the simple part, I would assume. The situation where
> each half of the lake is an outer relation with inner relations would
> make the process more complex as you would somehow have to make the
> inner relations on one of the outer relations move over to become
> inner relations to the other outer relation, while making only one of
> the outer relations define the whole lake.
>
> Having the CanVec data available is excellent, but stitching areas
> back together where they have been artificially split at a tile
> boundary is a bit of a bear for me. Anyone of the CanVec import
> experts out there have a bit of a tutorial lesson for me?
>
> Wolf Lake (Hand drawn) http://www.openstreetmap.org/browse/way/78288197
> Wolf Lake (Canvec natural:water)
> http://www.openstreetmap.org/browse/way/81345148
> Wolf Lake (Canvec outer relation)
> http://www.openstreetmap.org/browse/way/81400283
>
> --
> James
> VE6SRV
>
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