[Talk-ca] Merging canvec data into existing lakes

[Adam Dunn]

This kind of depends on quality of each source (has the lake been modified
since either OSM or Canvec traced it?).

I'll assume you're talking about a case where Canvec has better positional
data than OSM, but you don't want to wipe out OSM completely, or it could be
a while before you import the lake in other tiles (some lakes can span many
Canvec tiles and we don't want "half-lakes" on our maps!)

First check the lake in OSM to make sure there aren't any interesting tags
that could get lost (boat launches, alternative names, etc.)

If there's nothing of particular interest in OSM currently, what I do is
"split" (keyboard command 'p' in josm) the lake in OSM and Canvec at the
boundary of the tile, then delete the OSM data in the tile I'm importing,
and the line of the lake along the boundary in Canvec. So instead of having
two closed lakes (two "O" figures"), I now have two non-closed lakes (one
will be a "U" shape, the other an upside-down "U"). Then merge the nodes
(keyboard 'm') and combine the ways (keyboard 'c').

In the end you'll have one lake that is using Canvec data where you just
imported, and original OSM data where you haven't yet. When you get around
to importing the other areas, you split/merge/combine again so the whole
lake is now Canvec sourced.

Adam

On Thu, Nov 18, 2010 at 4:00 PM, Samuel <samueldyck at gmail.com> wrote:

> Hi
>
> How would I take canvec lake data into already mapped lakes that stretche
> outside the canvec tile?
>
> Sam
>
> _______________________________________________
> Talk-ca mailing list
> Talk-ca at openstreetmap.org
> http://lists.openstreetmap.org/listinfo/talk-ca
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/talk-ca/attachments/20101118/93101023/attachment.html>