Changes between Version 9 and Version 10 of Help/DEM_scripts

Timestamp:

Feb 11, 2012, 1:49:35 PM (13 years ago)

Author:

adbe

Comment:

--

Help/DEM_scripts

@@ -55 +55 @@
     *  Select the purpose of the tile usage
     *  Then download the tiles.
+
+==== Choosing Tiles ====
+When creating an ASTER DEM it is important to choose the correct tiles to use, as this could impact on the speed at which the script runs, as if tiles with large gaps between them are chosen when grass fills the nulls it has a lot of nulls to fill, so will take a very long time.
+I suggest that a square region of tiles should be chosen, as this means that the script should not need to fill a large number of nulls.
+If you require tiles in the region (50.23 - 52.56, -2.34 - 1.23) lat/lon:
+  To calculate the tiles round the numbers down to get (50 - 52, -3 - 1), so you need:
+     ASTGTM2_N50W003_dem.tif
+     ASTGTM2_N50W002_dem.tif
+     ASTGTM2_N50W001_dem.tif
+     ASTGTM2_N50E000_dem.tif
+     ASTGTM2_N50E001_dem.tif
+     ASTGTM2_N51W003_dem.tif
+     ASTGTM2_N51W002_dem.tif
+     ASTGTM2_N51W001_dem.tif
+     ASTGTM2_N51E000_dem.tif
+     ASTGTM2_N51E001_dem.tif
+     ASTGTM2_N52W003_dem.tif
+     ASTGTM2_N52W002_dem.tif
+     ASTGTM2_N52W001_dem.tif
+     ASTGTM2_N52E000_dem.tif
+     ASTGTM2_N52E001_dem.tif
+  The name of the tiles relates to the bottom left corner of the region so ASTGTM2_N50W003_dem.tif covers (50-50.9999, 3-3.0001).
 
 ==== Geoid Height Grid ====
@@ -131 +153 @@
 I would advise that the grass version be 6.3 as the script was written to work with this grass version.
 
+==== Using asterdem.sh ====
+The script is partly configured to be used in-house and so some options that are available are not applicable, as for example the navigation file is used to calculate the tiles to use by default. So here is a usage for out of house usage:
 
+asterdem.sh[[BR]]
+[[BR]]
+Generates a binary lat-long ASTER DEM from downloaded raw ASTER data[[BR]]
+[[BR]]
+Arguments:[[BR]]
+   (Optional)[[BR]]
+      -h:   Display usage and exit[[BR]]
+      -o:   Final output filename for DEM, defaults to leaving in grass database[[BR]]
+      -j:   Filename to output a jpeg image of the DEM[[BR]]
+      -a:   Directory containing ASTER tiles only. If not given then script needs to be run within a project[[BR]]
+      -g:   Grass database to use, defaults to creating one[[BR]]
+      -p:   Projection of output tiles:proj4 string or UTM[utm_num(zero padded)](N|S) or UKBNG or ll[[BR]]
+      -r:   Resolution of output DEM, defaults to using resolution of ASTER tile[[BR]]
+      -s:   binary geoid-spheroid seperation file[[BR]]
+      -m:   Maximum size of output DEM in GB, will be overridden by specified resolution. Note this does change the output resolution[[BR]]
+      -f:   Do not fill nulls or smooth, i.e. do not run the command r.fillnulls and r.neighbours on the DEM before outputting[[BR]]