LANDSAT: Difference between revisions

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(→‎Notes: examples)
Line 36: Line 36:


<source lang="bash">
<source lang="bash">
BASE=L71074092_09220040924_B
BASE=L71074092_09220040924


for BAND in 10 20 30 40 50 61 70 80; do
for BAND in 10 20 30 40 50 61 70 80; do
   BAND1st=`echo $BAND | sed -e 's/0$//'`
   BAND1st=`echo $BAND | sed -e 's/0$//'`
   r.reclass in="$BASE$BAND" out=$BASE.$BAND1st << EOF
   r.reclass in="${BASE}_B$BAND" out=$BASE.$BAND1st << EOF
     * = *
     * = *
EOF
EOF
Line 50: Line 50:


Identify clouds in the image:
Identify clouds in the image:
  i.landsat.acca -2 -f band_prefix=$BASE.toar out=accaout
  i.landsat.acca -2 -f band_prefix=$BASE.toar out=$BASE.acca





Revision as of 14:01, 9 September 2010

LANDSAT Data Availability

Modules

  • d.rgb - display 3-band data
  • i.landsat.rgb - auto-enhance colors
  • i.atcorr - correct top of atmosphere to surface reflectance
  • i.oif - calculate the 3 bands showing the greatest difference (for use as R,G,B bands)
  • r.composite - flatten 3-bands of data into a single image (lossy)

LANDSAT Pre-Processing

Some notes from Yann Chemin:

  1. Open GRASS GIS, select create location from georeferenced file
  2. Use r.in.gdal to import into GRASS GIS.
  3. In grass/add-ons look for any of these to correct from radiance to reflectance at top of atmosphere
    1. i.landsat.toar
    2. i.dn2full.l5
    3. i.dn2full.l7
  4. Use i.atcorr to correct top of atmosphere to surface reflectance

Notes

The i.landsat.toar and i.landsat.acca modules want the maps to be named such as "scenename.1, .2, .3", etc. for the different bands. GloVis names LANDSAT-7 like _B10, _B20, _B30, etc.

Here's a little trick with r.reclass to rename it without touching the data or wasting disk space:

BASE=L71074092_09220040924

for BAND in 10 20 30 40 50 61 70 80; do
  BAND1st=`echo $BAND | sed -e 's/0$//'`
  r.reclass in="${BASE}_B$BAND" out=$BASE.$BAND1st << EOF
    * = *
EOF
done

Calculate top-of-atmosphere reflectance:

i.landsat.toar -7 band_pre=$BASE metfile=L71074092_09220040924_MTL.txt

Identify clouds in the image:

i.landsat.acca -2 -f band_prefix=$BASE.toar out=$BASE.acca