Changes between Version 6 and Version 7 of Processing/SRTMDEMs


Ignore:
Timestamp:
Sep 9, 2010 3:28:29 PM (9 years ago)
Author:
benj
Comment:

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  • Processing/SRTMDEMs

    v6 v7  
    1111 * SRTM from http://earthexplorer.usgs.gov. Expand the "Digital Elevation" link on the left and tick the box labelled "SRTM". Enter bounding co-ordinates for the area you want data for, clicking the green "+" icon after each one. Note that this currently seems not to always work correctly for locations in DMS format (at least in Firefox), you may need to switch to decimal degrees (which work fine). Click on the "Search" button in the bottom-right, and you should be presented with a list of items matching your search (there should be only one thing in it). Click on the "SRTM" link (you may need to enable pop-ups if you've got them blocked), and you will be presented with a list of matching SRTM tiles and download links - download the data you want to use. Note that only SRTM 3-arc-second resolution data is available for sites outside North America. For sites in North America higher resolution data can be obtained via the USGS [http://seamless.usgs.gov/ Seamless Server]
    1212
    13 2. Unzip the downloaded zip file. ASTER data will contain two GeoTIFFs (you want the "_dem" one). For SRTM data, descend into the directory structure to find the file w001001.adf - this holds the actual data, though you can't move it without the rest of the directory structure.
     132. Unzip the downloaded zip file. ASTER data will contain two GeoTIFFs (you want the "_dem" one) - the file name refers to the lat/lon of the bottom-left corner of the tile. For SRTM data, descend into the directory structure to find the file w001001.adf - this holds the actual data, though you can't move it without the rest of the directory structure.
    1414
    15153. Fire up Grass. Select a location in lat/long projection using WGS84 datum (create one if none avaialble), make a note of the selected location and mapset names.