[Talk-us] NHD import and conversion - sample data

[Ben Supnik]

Hi Y'all,

So first: a new extraact is attached with...

- Dupes removed.
- GNIS names fixed.
- One file per export.

http://dev.x-plane.com/download/01090001.zip

(Be sure to nuke caches to get the build from today's date...)

On 4/29/11 9:51 AM, James Umbanhowar wrote:

> 2.  You should use one file per attribute.  If you are using Ian's shp-to-osm
> tool, crank up the changeset size to some very large value to accomplish this.

That seems to work so far...I had to boost heap size to cope with the 
flow line files.

> 3.  Duplicate nodes need to be merged, especially in the flowline files.  The
> data currently have duplicate nodes a every point where one reach intersects
> another.  This creates many duplicate nodes.  The Corine data import folks
> wrote a java tool to remove these
> (http://wiki.openstreetmap.org/wiki/WikiProject_Corine_Land_Cover/Corine_Data_Import)
> which I use to remove the duplicate nodes.

With some modification, that seems to have worked.

> 4.  The conversion rules you are using seem to have a lot of issues.  I see
> some of these on the default rules for shp-to-osm wiki page and I have
> corrected them where I see them, but others I can't identify their source:

So first, those rules did come off the wiki.  For some reason, 
capitalization in the shapefiles is...a bit funky.  I tried to fix some, 
but may have missed them.

The GNIS names are just me being stupid - I fixed all capitalization 
issues except for that one.  The other issues (specific codes) are due 
to the limits of the rule set I took.

Since the posted sub-basin dump has the original .shp files, would it be 
simpler for you to simply correct the rules and then send me back the 
rule sheet you used for inclusion directly in my process?

> 	f.  It would probably be good to have a discussion of how much of the
> additional NHD/GNIS tags we want to import.  I think we should import the
> FCODE and

That's beyond my pay grade...I'll trust whatever y'all come up with. :-)

> 	g.  In points and lines files there were many things that had no osm tags
> including gauging stations and nonearthen shores.  We should not import things
> that have no osm tags.

Hrm...interesting.  The tools don't currently strip untagged data, do 
they?  Is there an existing tool that strips 'null' data?

> 5.  Once we set this up, we'll need to give a fair bit of guidance on what
> sorts of things to look for.  One thing that is quite tricky is importing
> coastline.  One has to make sure that you delete all the previously existing
> coastline in the area and to connect the new coastline at the edges of its
> extent.  Given the poor resolution of the PGS and the general disagreement
> between it and USGS on whether tidal riverbanks are coastline or not this can
> be quite a bit of work.

Right...I would go a step further and say that I'd be terrified of the 
results of users attempting to use these extracts to create coastline 
without a lot of experience.  In some cases, the cut-over where OSM 
switches from coastline edge marking to closed water bodies might not be 
in the same place as NHD.

cheers
ben




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