[Talk-us] NHD data import question

[James Umbanhowar]

On Thursday 28 April 2011 08:53:56 Ben Supnik wrote:
> Hi Ian,
> 
> I should be able to convert the NHD data sometime in the next week or
> so.  Also, if/when you want the original data, let me know.
> 
> For the conversion, do we want medium or high resolution?
> 
> Re: the import status map, I don't know how to make an actual map from
> them....short of simply providing a KML file and saying "go look on
> Google Earth", what formats are most useful for making an overlay status
> map?  (I could do that conversion and hand it off to someone.)
> 
> cheers
> ben
> 

I've been checking some of the imported data and my general feel is that it is 
overdigitized.  I don't know if medium versus high reflects just the quality or 
the amount of digitization.  That would be something to check.  One could also 
just run some sort of simplification algorithm on all the data.

Also, are the plans to make one file for each subbasin or one file per attribute 
(flowline, waterbody etc...).  With one file, one can remove all the duplicate 
nodes before uploading.

Maybe it would be useful to do a test subbasin with whatever toolchain you're 
going to use and then post it so that mappers can check to see how the 
conversion meshes with our general wants.


> On 4/28/11 8:48 AM, Ian Dees wrote:
> > Yep: if you have the ability and time to cut the national dataset into
> > subbasins I'll give you an SFTP to upload them to and I'll start
> > converting them to OSM.
> > 
> >  From there we could add links to the pre-converted subbasin OSM bundles
> > 
> > to the wiki pages.
> > 
> > Bonus points for converting the subbasin boundary files to
> > KML/GeoJSON/GML and overlaying them on a "import status" map that a user
> > could click on to find their subbasin. I'd be happy to host all this.
> > 
> > -Ian
> > 
> > On Thu, Apr 28, 2011 at 7:37 AM, Ben Supnik <bsupnik at xsquawkbox.net
> > 
> > <mailto:bsupnik at xsquawkbox.net>> wrote:
> >     Hi Y'all,
> >     
> >     So let me see if I can summarize where we are so far...
> >     
> >     - I could cut the NHD data down to sub-basins. It would not be a
> >     perfect cutting (e.g. each sub-basin might need a little bit of data
> >     "hanging off" since the raw data isn't cut on sub-basin boundaries)
> >     but it would be pretty close, and we expect users to manually check
> >     their imports.  I could also potentially convert the shapefiles to
> >     .osm format on a sub-basin basis.
> >     
> >     - It would be nice to make it easier for users to find their
> >     sub-basins.  I'm afraid I don't know how to use the mapnik tool
> >     chain to create a slippy map though.  (Left to my own, I would
> >     probably convert the sub-basin boundaries to KML...that makes me a
> >     heretic, right? :-)  We could also just post the boundary shapefile,
> >     but some users may not be comfortable with shapefiles.
> >     
> >     - Importing on a sub-basin basis should be possible in JOSM, if not
> >     a bit of a mouthful.  Importing via potlatch2 vector layers should
> >     be possible - others have seen this work although I have not.
> >     
> >     cheers
> >     Ben
> >     
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