[Talk-us] NHD import

Toby Murray toby.murray at gmail.com
Mon Apr 9 08:59:54 BST 2012


On Mon, Apr 9, 2012 at 1:25 AM, Gregory Arenius <gregory at arenius.com> wrote:
>
>
>
>> Yes, I see a lot of water features that are just not corroborated by the
>> aerial imagery, which could mean one of at least three things:
>> 1) The aerial imagery is out of date
>> 2) The NHD data is out of date
>> 3) The NHD data represents something I don't understand (the future, a
>> temporary situation (which should not be in OSM), something underground?)
>>
>
> Some of the water features in NHD are also seasonal, although that is
> usually tagged in the data.   Also irrigation canals are often just ditches
> and can be hard to identify from aerial imagery especially the smaller ones
> as they aren't always in use.
>
> The tags on a lot of those features have some gnis:type tags that say
> ditch-canal or something like that but the OSM tag is just canal which
> doesn't really do a great job describing the situation exactly.
>
> I agree, though, the data you pointed out looks pretty odd, especially the
> square shapes.
>
> I'm surprised that NHD has data that includes irrigation ditches as small as
> some of the ones noted above.  Anybody know how they gathered all of that
> data?
>
> Greg

I saw some odd water features along the coast in California as well
when I was remapping coastlines by importing some NHD data. I don't
have a link handy but I think it came from a California specific data
source and some of the ways didn't have any OSM renderable tags.

Yay for imports?

Toby



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