On 14/03/2016 20:50, Rob Nickerson wrote:
My concern with rivers is that we don't have tools to measure progress - taginfo gives a count of nodes/ways/relations whereas we'd want total length of features per region (in miles/km).
I'd agree that tracking progress with that one would be tricky. I've mapped lots of rivers and streams from a combination of survey, imagery and OS OpenData, and while we've got something approaching the "length" of major rivers and streams, what we've got in some areas is largely ex-NPE, and in many cases some distance from the actual waterway on the ground.
GPS traces (unless there are lots) and Bing imagery can of course be misplaced, but OS OpenData is normally pretty good (actually better than the OS vector data that people have imported in a couple of areas) although it can be wrong when watercourses have changed, and the top end of small Welsh streams is often a bit "wishful thinking" in OSSV - where in reality there's just a boggy mess the OS sometimes has well-defined streams.
The other problem with the waterways we've got in OSM is that many are just either "stream" or "river" - with things that I'd normally map as drains and ditches just in as "stream". Obviously changing a tag post-survey is pretty straightforward, but it's something else to bear in mind.
There is a real benefit of having OSSV streams, ditches and drains in though - it's often clear that a watercourse hasn't moved for years, and it can then be used to help align imagery and GPS traces.
Cheers, Andy (SomeoneElse) _______________________________________________ Talk-GB mailing list [email protected] https://lists.openstreetmap.org/listinfo/talk-gb
