[Talk-ca] Merging ways

[Adam Dunn]

My involvement with OSM predates Potlatch by a couple months, so I
learned to edit OSM with JOSM, and that's what feels most natural to
me. I get frustrated trying to use Potlatch. The complete opposite of
you :)

Your data looks good, except for one thing: you tagged the way with
the name, whereas the proper thing is to tag the relation with the
name. The way should have no tags in this case (there may be other
cases where the way would have tags even though is a member of a
relation, but not in this case).

For >1K, I split at approx the half-way mark. Doesn't need to be
exactly half. Linear ways (highways, etc) just get split and left as
two ways, whereas polygons (lakes, forests) get split and then made
into a multipolygon relation. I think that having boundaries will be
inevitable, especially when mapping out forests of Canada (a forest
relation could extend hundreds of kilometers!). I'm currently
experimenting with making Great Slave Lake a giant multipolygon, which
may end up being the largest multipoly in OSM, since GSL is the 9th
largest lake in the world, and I expect the 8 larger are tagged with
coastline. I'm doing this to see how well the renderers deal with this
case. I wouldn't suggest making multipolys so large, and they should
be divided at smaller areas. Where to split is up to you, and how
large to make a multipoly is up to you, just as long as an individual
way does not exceed 2000 nodes.

Just to be sure you're aware:
http://wiki.openstreetmap.org/wiki/Relation:multipolygon

Happy mapping!

Adam

On Sun, Aug 21, 2011 at 9:33 PM, James Ewen <ve6srv at gmail.com> wrote:
> On Sun, Aug 21, 2011 at 9:14 AM, Adam Dunn <dunnadam at gmail.com> wrote:
>
>> 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".
>
> Not sure what was going on there, but Potlatch 2 didn't want to play nice.
>
> I watched your videos and decided to give JOSM yet another go... I've
> tried twice before and both times gave up in disgust with trying to
> figure out the arcane logic behind using JOSM. Perhaps I have learned
> a bit over the years using other editors, like Merkaartor, but this
> time I had better luck.I still hate using an editor with defined
> modes. There are far too many extra button presses to get it to just
> do what you want. Just to add a node to an existing way I have to
> press A, then click on the node, then hit ESC to stop adding a way.
> Why not just shift-click on the way like you do in Potlatch? I found
> where you can select having JOSM go to modeless like Potlatch but it
> doesn't seem to make any changes.
>
> Anyway, I think I managed to merge a few ways to create a one piece
> version of Wolf Lake. I don't think I've buggered anything up, but
> time will tell. About a week from now, if Wolf Lake disappears, we'll
> know why.
>
> Video tutorials like the ones you made are a great help. Trying to
> follow along in a written help file can be pretty tough if you have no
> idea what they are telling you to look for, or where to find the
> buttons to press. The video help was nice and easy to follow, and I
> was able to replicate the instructions given without having to go back
> and watch the video again to figure out what you had done.
>
> Thanks for the help Adam!
>
>
> BTW, what do you do with an entity that has over 1000 nodes? You said
> you don't like to make any that big. Do you just arbitrarily cut lakes
> or forests into bits? Should I just leave the Canvec tile boundaries
> in place if the lake is too big? When you zoom in, the lines show up,
> which isn't all that desirable. The only other way to reduce the
> number of data points would be to reduce the precision level of the
> depiction of the feature, which also is not desirable.
>
> --
> James
> VE6SRV
>
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