HOWTO import USGS elevation data: Difference between revisions
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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. ( | 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 | 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.