[Talk-GB] tracing lakes with Potlatch

[Phil James]

> Date: Tue, 06 Apr 2010 13:37:58 +0100
> From: Henry Gomersall <heng at cantab.net>
> Subject: [Talk-GB] tracing lakes with Potlatch
> To: talk-gb at openstreetmap.org
> Message-ID: <1270557478.9949.39.camel at whg21-laptop>
> Content-Type: text/plain; charset="UTF-8"
>
> Dear All,
>
> I've been keen for a while to improve the lake and tarns outlines in the
> lake district. It seems the current data is a little coarse and could be
> improved. The (fairly poor) aerial imagery seems plenty good enough to
> get a decent outline, but Potlatch won't allow zooming beyond a certain
> level in this region, which makes it difficult. Is this something the
> Potlach 2 will allow? Also, is it worth bothering, as it seems some of
> the new OS datasets will have decent lakes and rivers.
>
> Cheers,
>
> Henry
>   
I've been tracing from the OS 1:25k first series which Andy Robinson is 
uploading as a potlatch layer. (see 
http://www.openstreetmap.org/?lat=54.5384502410889&lon=-2.8754997253418&zoom=13and 
http://www.openstreetmap.org/?lat=54.3379497528076&lon=-2.28412628173828&zoom=13 
). You can trace at zoom level 17, and the rectification of the maps is 
pretty good (compare roads on the maplayer with gps traces). The yahoo 
imagery for rural areas is worse than useless, IMHO, and the NPE is not 
well rectified - a comment on the standard of the original mapping, not 
those who rectified the data for OSM use, I hasten to add.

There are very few of the maps available in the Lakes at the moment, but 
I'm hopeful Andy will continue to upload once the furore over OSOpenData 
has settled a little.
As for the comment from another contributor suggesting don't bother 
tracing - I say go for it, so long as you have local knowledge of the 
areas concerned - look further afield (Dales, N York moors etc if you 
know the areas) and get some detail on, but use the best source for 
tracing available; which at the moment is OS1:25k First Edition.

Cheers,

Phil.