[Talk-us] NHD conversions to OSM

[Ian Dees]

On Thu, Jun 9, 2011 at 2:43 PM, Josh Doe <josh at joshdoe.com> wrote:

> I've gone ahead and cleaned up the NHD page a bit.
>
> I've also looked at the data, and I must say I'm confused! One river
> is represented in the flh file as waterway=stream, in arhi as
> waterway=riverbank, in flmd as waterway=stream (but with worse spatial
> accuracy than flh), and then in armd as waterway=riverbank! I suppose
> one of the waterway=stream's should be changed to waterway=river, and
> only one of the waterway=riverbank objects should be used.
>
> Is this really what the NHD data is like? It will take more time than
> I thought to properly merge these these 6 or 7 layers.
>
>
Yes. You should only be using "high" resolution. "High" resolution is
already a bit too low for OSM and "medium" is even worse. The "area" dataset
consists of polygons that represent rivers wider than a certain cut-off
width. Below that width they are represented only as flowlines. Above that
width they are represented as flowlines of type "artificial" and a polygon
in the "area" dataset.

I would suggest reading the NHD data description. It's only a few pages of
text if you skip some of the code/type mappings.


> If I am confused, then please enlighten me. Preferably by putting it
> in the wiki :)
> http://wiki.openstreetmap.org/wiki/NHD
>
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