[OSGeo-Discuss] Re: Digital Nautical Charts

[Frank Warmerdam]

John Griffiths wrote:
> Frank et al,
> Took me a while since the data I am working with came to me second hand.
> 
> The data can be downloaded here:
>  http://www.nga.mil/portal/site/dnc/index.jsp?epi-content=GENERIC&regionTitle=DNCDX017%20-%20Eastern%20United%20States&regionEdition=040&channelID=4a0874dd2cd3cf00VgnVCMServer3c02010a____&regionNtMDate=02%2F08&beanID=30513340&viewID=library_list

John,

This DNC data works with OGR.  On Windows for instance, I can issue the
following command to see a list of layers for a dataset unpacked in
\warmerda\wrk\dnc17:

  ogrinfo -ro gltp:/vrf/warmerda/wrk/dnc17/a1707300

The report shows rather esoteric names for layers like "riverl at iwy(*)_line".
You can get a list of features in a layer like:

  ogrinfo -ro gltp:/vrf/warmerda/wrk/dnc17/a1707300 "riverl at iwy(*)_line"

Note the quoting of the layer name since it contains fair special characters
for the shell.

This access depends on having an OGR that is built with OGDI support - which
is certainly not a default option.  So, while in theory you could import
the data with the GRASS v.in.ogr, it is unlikely your GRASS build includes
an OGR with OGDI support.  A work around is to use an appropriately built
OGR external to GRASS to translate the data into an intermediate format,
like Shapefiles.

eg.

   ogr2ogr riverl.shp gltp:/vrf/warmerda/wrk/dnc17/a1707300 "riverl at iwy(*)_line"

Then use that in grass.

The FWTools binaries for windows and linux available from:

   http://fwtools.maptools.org/

Include OGDI support.  Lastly, I must warn you that the OGDI driver for VRF
data is very sensitive to upper and lower case file naming on Linux and
other case sensitive filename systems.  If you can easily do the translation
on windows that may be best.  Otherwise you may need to do something like
convert all the files to lower case.

Best regards,
-- 
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I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org