ASTER topography

Download

The one-by-one-degree tiles can be downloaded

• from NASA's EOS data archive and/or
• from Japan's Ground Data System

Steps to import ASTER GDEM tiles in GRASS:

# save downloaded zip files in one directory
# enter in directory and unzip files at once
unzip "*.zip"

# create WGS84 location, import elevation (=dem) and quality (=num) tiles in PERMANENT mapset
for GDEM in *.tif ; do
  r.in.gdal in=$GDEM out=`basename ${GDEM} .tif`
done

# match region to extent of imported gdem tiles
g.region rast=`g.mlist pat=AST*dem sep=,` -p

# patch tiles in one map
r.patch in=`g.mlist pat=AST*dem sep=,` out=aster_gdem

# assign colors
r.colors aster_gdem color=terrain

Note 1: You can also mosaic all tiles with gdalwarp and wildcards:

 gdalwarp AST*.tif mosaic.tif

Note 2: Experimenting on color rules that replicate NASA's "GDEM press colorized topo" published at "Mission News". Some color rules to start with...

# create a file (named for example aster_gdem) under the directory /etc/colors within the local grass installation (e.g. /usr/local/grass-6.4.0svn/etc/colors/aster_gdem)

# copy-paste the following rules
-11000 black
-500 0 0 10
-300 0 0 20
-200 0 0 70
-100 0 0 130
-50 0 0 205
0 black
0.1  123 123 164
50   123 123 255
100  41  156 41
160  164 180 41
350  230 230 41
610  164 205 41
1100 164 213 41
1200 213 255 148
1500 205 255 139
2000 215 255 155
2300 238 238 24
3000 255 255 0
3800 255 213 41
4000 255 150 0
5500 255 255 255
nv white

# apply colors
r.colors aster_gdem color=aster_gdem

See also

• http://gis.fem-environment.eu/aster-gdem-quality/
• https://arrowsmith.blog.asu.edu/2009/07/27/looking-at-the-new-aster-30-m-dems-not-so-impressive-relative-to-srtm-90-m
• http://www.geomorphometry.org/content/gdem-quick-assessment
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