Difference between revisions of "HOWTO import USGS elevation data"

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(r.in.gdal -e flag recommended)
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== Importing USGS 1/3" NED datasets into GRASS ==
== Importing USGS 1/3" NED datasets into GRASS ==


1. Download the datasets you desire. They will arrive in a zip archive of a directory containing a subdirectory containing a file called w001001.adf, which is the main data file (tip: this is the biggest file).
1. '''Download the datasets you desire.''' They will arrive in a zip archive of a directory containing a subdirectory containing a file called w001001.adf, which is the main data file (tip: this is the biggest file).


2. '''Create a new GRASS location to work with the DEMs.'''
2. '''Create a new GRASS location to work with the DEMs.'''
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: <code>r.in.gdal location=''name_of_your_new_location'' in=w001001.adf out=dem</code>
: <code>r.in.gdal location=''name_of_your_new_location'' in=w001001.adf out=dem</code>


3. (re)Start GRASS in the new location.
3. '''Start GRASS''' (or restart) in the new location.
: <code>grass name_of_your_new_location/PERMANENT</code>


4. Import additional files as needed (note the <code>-e</code> flag causing the location's bounds to be extended as needed):
4. Import additional files as needed (note the <code>-e</code> flag, which causes the location's bounds to be extended to accomodate the new data):
: <code>r.in.gdal -e in=w001001.adf out=dem2</code>
: <code>r.in.gdal -e in=w001001.adf out=dem2</code>
: ''.. etc.''
: ''.. etc.''

Revision as of 18:08, 22 May 2007

The US Geological Survey offers a variety of digital elevation models through the Seamless Distribution System. Here is an approach to working with them in GRASS.

Importing USGS 1/3" NED datasets into GRASS

1. Download the datasets you desire. They will arrive in a zip archive of a directory containing a subdirectory containing a file called w001001.adf, which is the main data file (tip: this is the biggest file).

2. Create a new GRASS location to work with the DEMs.
From a GRASS shell:

cd 18437824/18437824 (example directory names --- replace with your actual names)
r.in.gdal location=name_of_your_new_location in=w001001.adf out=dem

3. Start GRASS (or restart) in the new location.

grass name_of_your_new_location/PERMANENT

4. Import additional files as needed (note the -e flag, which causes the location's bounds to be extended to accomodate the new data):

r.in.gdal -e in=w001001.adf out=dem2
.. etc.

5. Use r.patch to combine the tiles into one continuous map, if desired.