[Talk-us] NHD import: what data quality is acceptable?

Paul Norman penorman at mac.com
Mon Jul 23 02:33:04 BST 2012


> From: Kevin Kenny [mailto:kkenny2 at nycap.rr.com]
> Subject: [Talk-us] NHD import: what data quality is acceptable?
> 
> A few months ago, I tried to get started on trying to resume the NHD
> import in my area - and some of the places where I hike. I'm trying to
> check results with both P2 and JOSM, and tripping over a lot of things,
> which made me put the project back on hold for a while. (I had some
> other things to be about.)
> 
> But now I'm starting to reconsider again, after hearing that there are
> others out there thinking the NHD import is desirable for an "Open Trail
> Map." I mentioned this in a message earlier today.
> 
> So, let me review some of the things that have me scratching my head.
> 
> (1) The mapping from NHD feature codes to OSM tags is incomplete (and
> not quite consistent). That's fine; for all the FCodes in my area, I've
> been able to find features that I'm familiar with that I can describe.
> So I think I have that problem fairly well licked. (I may have to invent
> a tag or two, like "waterway=rise" and "waterway=sink" to describe
> streams that go underground and appear again in karst terrain.)

The mappings on the wiki are not only incomplete and inconsistent, they're
for an older NHD version and sometimes clearly wrong.

I posted a better one
(http://lists.openstreetmap.org/pipermail/talk-us/2012-July/008502.html)
earlier this month but it didn't attract any comments, and it's not complete
either. It handles most of the FCodes but still is missing a couple. It also
needs some post-processing to clean up over-noded ways and some other
matters.

The main weakness with NHD data that I find is that there is no way to
distinguish between an OSM waterway=stream and waterway=river




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