[gdal-dev] Working with USGS NED data

[Dylan Beaudette]

Supposing that you had the road network and USGS NED data loaded into
GRASS, you could use the v.drape command:

http://grass.itc.it/grass65/manuals/html65_user/v.drape.html

You may be able to automate this, by looping over counties,
downloading the minimum NED required, running v.drape, and then saving
the result.

Alternatively, you could craft a python solution that loops over
vertices of the road network, and submits requests to the NED point
elevation lookup. This would obviously be very slow, and possibly
memory-bound--- therefor you would need to chunk the operation,
possibly by county.

Do you really need the precision of the 1/3 arc second data? You do
realize that this is possibly a multi-terabyte data set?

Cheers,
Dylan

On Wed, Aug 18, 2010 at 6:38 PM, Stephen Woodbridge
<woodbri at swoodbridge.com> wrote:
> Hi all,
>
> I plan to download the USGS NED 1/3 arcsec dataset and I noticed it is
> available in 2 formats: ArcGrid and GridFloat
>
> Is one easier, faster, smaller, etc to work with than the other?
>
> My goal is to augment the Tiger road network with Z elevation data.
>
> I'm wondering if there is a tool that already does this, like read a
> shapefile, augment with elevation and write a new shapefile. Or if I would
> need to write a tools that does that. Can postgis be used to do this?
>
> Given a lat,lon, what is the fastest way to get the elevation?
>
> Thank you for any input you can provide.
>
> -Steve
>
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