[Talk-GB] tracing lakes with Potlatch

Jason Cunningham jamicuosm at googlemail.com
Tue Apr 6 17:26:21 BST 2010


On 6 April 2010 13:37, Henry Gomersall <heng at cantab.net> wrote:

> .... is it worth bothering, as it seems some of
> the new OS datasets will have decent lakes and rivers.
>
> Cheers,
> Henry
>

I'd say it's not worth the effort tracing. I had a look at the 'water area'
and 'water line' layers in the 'VectorMap District' example provided. The
'VectorMap District' product is due to be released next month.
The detail for water is excellent and may be the most 'detailed' vector data
OS is going to provide. It's far better than the OSM community could achieve
with GPSr's and aerial image tracing.

I've mentioned this in another post, but I had a look at the 'water area'
and 'water line' data yesterday. OS map areas of water/streams greater than
1m, and do it very accurately. Streams less than 1m are mapped as simple
lines.
But where a bridge/path goes over the water the water does not exist, so the
data will need to be stitched together (in JOSM?) using personal knowledge.
Below is the example I produced to show the missing sections of a stream in
Milton Keynes where a road bridge and path bridge cross the stream. You can
see the roads/paths in the aerial image of the second link
http://i227.photobucket.com/albums/dd132/jamicu/grassvectorofwaterinMiltonKeynes.jpg
http://snipurl.com/v9xsq

Hopefully 'the community' can reach agreement on how the vector data will be
used. I hope it will be converted in to 2km files that can be viewed in
JOSM, the corresponding OSM info for the area can then be downloaded, then
the two brought together with some though given to the results.

Cheers,

Jason Cunningham
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/talk-gb/attachments/20100406/1acbb05a/attachment-0001.html>


More information about the Talk-GB mailing list