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 <wood...@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 > > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/gdal-dev > _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
