LANDSAT
LANDSAT Data Availability
- data download from USGS LANDSAT archive and GLCF and EarthExplorer and USGS GloVis
- see also the Global datasets wiki page
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)
- i.landsat.toar (addon, included in GRASS 7) - convert DN to top of atmosphere radiance
- i.landsat.acca (addon) - cloud identification
- i.landsat.dehaze (addon) - haze removal
LANDSAT Pre-Processing
- see also the Atmospheric correction wiki page
Some notes from Yann Chemin:
- Open GRASS GIS, select create location from georeferenced file
- Use r.in.gdal to import into GRASS GIS.
- Most landsat scenes are delivered in "north-is-up" orientation, hence import is straightforward
- If you get "ERROR: Input map is rotated - cannot import.", the image must be first externally rotated, applying the rotation info stored in the metadata field of the raster image file. For example, the gdalwarp software can be used to transform the map to North-up (note, there are several gdalwarp parameters to select the resampling algorithm):
gdalwarp rotated.tif northup.tif
- In grass/add-ons look for any of these to correct from radiance to reflectance at top of atmosphere
- 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.
Import data
An example of Python script bellow imports raster data into GRASS. For each image creates its own mapset and imports bands as B<id>, e.g. B10, B20, ..., B80. This script also sets up timestamp based on MTL file.
#!/usr/bin/python
import os
import sys
import glob
import grass.script as grass
def get_timestamp(mapset):
try:
metafile = glob.glob(mapset + '/*MTL.txt')[0]
except IndexError:
return
result = dict()
try:
fd = open(metafile)
for line in fd.readlines():
line = line.rstrip('\n')
if len(line) == 0:
continue
if 'ACQUISITION_DATE' in line:
result['date'] = line.strip().split('=')[1].strip()
finally:
fd.close()
return result
def import_tifs(mapset):
meta = get_timestamp(mapset)
for file in os.listdir(mapset):
if os.path.splitext(file)[-1] != '.TIF':
continue
ffile = os.path.join(mapset, file)
name = os.path.splitext(file)[0].split('_')[-1]
kanal = int(name[-2])
grass.message('Importuji %s -> %s@%s...' % (file, name, mapset))
grass.run_command('g.mapset',
flags = 'c',
mapset = mapset,
quiet = True,
stderr = open(os.devnull, 'w'))
grass.run_command('r.in.gdal',
input = ffile,
output = name,
quiet = True,
overwrite = True,
title = 'kanal %d' % kanal)
if meta:
year, month, day = meta['date'].split('-')
if month == '01':
month = 'jan'
elif month == '02':
month = 'feb'
elif month == '03':
month = 'mar'
elif month == '04':
month = 'apr'
elif month == '05':
month = 'may'
elif month == '06':
month = 'jun'
elif month == '07':
month = 'jul'
elif month == '08':
month = 'aug'
elif month == '09':
month = 'sep'
elif month == '10':
month = 'oct'
elif month == '11':
month = 'nov'
elif month == '12':
month = 'dec'
grass.run_command('r.timestamp',
map = name,
date = ' '.join((day, month, year)))
def main():
if len(sys.argv) == 1:
for directory in filter(os.path.isdir, os.listdir(os.getcwd())):
import_tifs(directory)
else:
import_tifs(sys.argv[1])
if __name__ == "__main__":
main()
Example of usage:
- ./import.py walk through current directory and import all found satellite images.
- ./import.py LM41890261983200FFF03 imports images only from given directory.
Minimal disk space copies
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
Reset color tables
for map in `g.mlist pat="$BASE.[0-8]*"` ; do
r.colors $map color=grey255
done
Create an MASK to only show data where coverage exists for all bands
g.region rast=$BASE.1
r.series in=`g.mlist pat="$BASE.[0-8]*" sep=,` -n out=$BASE.thresh method=threshold thresh=1
r.mapcalc "$BASE.mask = if(isnull($BASE.thresh))"
g.remove $BASE.thresh
Calculate top-of-atmosphere reflectance and band-6 temperature:
i.landsat.toar sensor=7 band_pre=$BASE metfile=${BASE}_MTL.txt
Identify clouds in the image:
i.landsat.acca -s -f band_prefix=$BASE.toar out=$BASE.acca
Mask out the clouds:
r.mapcalc "MASK = if(isnull($BASE.acca))"
Sample data
The North Carolina 2008 sample dataset comes with 3 different Landsat scenes:
- (Wake County -- path: 16 row: 35 for various dates)
Landsat-5: Oct 14, 1987
- Glovis download
- LT50160351987287XXX08
- http://edcsns17.cr.usgs.gov/cgi-bin/EarthExplorer/run-phtml/results/download.phtml?node=GV&ordered=LT50160351987287XXX08&dataset_name=LANDSAT_TM
Provided metadata:
IMAGE_ID=P016R35_5T871014 PATH=16 ROW=35 DATE=10/14/87 PLATFORM=LANDSAT5
Landsat-7: Mar 31, 2000
- Glovis download
- LE70160352000091EDC00
- http://edcsns17.cr.usgs.gov/cgi-bin/EarthExplorer/run-phtml/results/download.phtml?node=GV&ordered=LE70160352000091EDC00&dataset_name=LANDSAT_ETM
Values in the metadata below indicate that the version provided with the NC 2008 dataset's production date was after July 1, 2000, and that the channel gains were HHHLHLHHL.
Convert DNs to radiance/temperatures:
GRASS> i.landsat.toar -v band=lsat7_2000 sensor=7 date=2000-03-31 \ product_date=2000-07-02 solar_elevation=51.5246529 gain=HHHLHLHHL
Provided metadata:
SPACECRAFT_ID=Landsat7 SENSOR_ID=ETM+ ACQUISITION_DATE=2000-03-31 WRS_PATH=16 CPF_FILE_NAME=L7CPF20000101_20000331_12 SUN_AZIMUTH=139.6033279 SUN_ELEVATION=51.5246529 LMAX_BAND1=191.600 LMIN_BAND1=-6.200 LMAX_BAND2=196.500 LMIN_BAND2=-6.400 LMAX_BAND3=152.900 LMIN_BAND3=-5.000 LMAX_BAND4=241.100 LMIN_BAND4=-5.100 LMAX_BAND5=31.060 LMIN_BAND5=-1.000 LMAX_BAND61=17.040 LMIN_BAND61=0.000 LMAX_BAND62=12.650 LMIN_BAND62=3.200 LMAX_BAND7=10.800 LMIN_BAND7=-0.350 LMAX_BAND8=243.100 LMIN_BAND8=-4.700 QCALMAX_BAND1=255.0 QCALMIN_BAND1=1.0 QCALMAX_BAND2=255.0 QCALMIN_BAND2=1.0 QCALMAX_BAND3=255.0 QCALMIN_BAND3=1.0 QCALMAX_BAND4=255.0 QCALMIN_BAND4=1.0 QCALMAX_BAND5=255.0 QCALMIN_BAND5=1.0 QCALMAX_BAND61=255.0 QCALMIN_BAND61=1.0 QCALMAX_BAND62=255.0 QCALMIN_BAND62=1.0 QCALMAX_BAND7=255.0 QCALMIN_BAND7=1.0 QCALMAX_BAND8=255.0 QCALMIN_BAND8=1.0
Landsat-7: May 24, 2002
- Glovis download
- LE70160352002144EDC00
- http://edcsns17.cr.usgs.gov/cgi-bin/EarthExplorer/run-phtml/results/download.phtml?node=GV&ordered=LE70160352002144EDC00&dataset_name=LANDSAT_ETM
Provided metadata: (`p016r035_7x20020524.met`)
SPACECRAFT_ID=Landsat7 SENSOR_ID=ETM+ ACQUISITION_DATE=2002-05-24 WRS_PATH=016 WRS_ROW=035 SUN_AZIMUTH=120.8810347 SUN_ELEVATION=64.7730999 QA_PERCENT_MISSING_DATA=0 CLOUD_COVER=0 CPF_FILE_NAME=L7CPF20020401_20020630_03 LMAX_BAND1=191.600 LMIN_BAND1=-6.200 LMAX_BAND2=196.500 LMIN_BAND2=-6.400 LMAX_BAND3=152.900 LMIN_BAND3=-5.000 LMAX_BAND4=241.100 LMIN_BAND4=-5.100 LMAX_BAND5=31.060 LMIN_BAND5=-1.000 LMAX_BAND61=17.040 LMIN_BAND61=0.000 LMAX_BAND62=12.650 LMIN_BAND62=3.200 LMAX_BAND7=10.800 LMIN_BAND7=-0.350 LMAX_BAND8=243.100 LMIN_BAND8=-4.700 QCALMAX_BAND1=255.0 QCALMIN_BAND1=1.0 QCALMAX_BAND2=255.0 QCALMIN_BAND2=1.0 QCALMAX_BAND3=255.0 QCALMIN_BAND3=1.0 QCALMAX_BAND4=255.0 QCALMIN_BAND4=1.0 QCALMAX_BAND5=255.0 QCALMIN_BAND5=1.0 QCALMAX_BAND61=255.0 QCALMIN_BAND61=1.0 QCALMAX_BAND62=255.0 QCALMIN_BAND62=1.0 QCALMAX_BAND7=255.0 QCALMIN_BAND7=1.0 QCALMAX_BAND8=255.0 QCALMIN_BAND8=1.0