[GRASS-user] Landsat Processing in PyGrass

[Joseph Kariuki]

Hi,

I am new to pygrass, I got the landsat processing script from osgeo pygrass
wiki page. I am stuck here at looping through landsat directories that I
have already created through unzipping lansat .gz archives. Kindly assist,
code is a shown below, the error being raised is
* for L7Dir in L7Dirs:TypeError: 'NoneType' object is not iterable*

#!/usr/bin/env python

# PURPOSE
# This script processes LANDSAT 7 ETM+ images
# 1 - unzip *.gz files
# 2 - import files in GRASS GIS Location of your choice (r.in.gdal)
# 3 - DN to Top of Atmosphere reflectance (i.landsat.toar)
# 4 - TOA reflectance to Surface reflectance (i.atcorr)
# 5 - NDVI (i.vi), Albedo (i.albedo), Emissivity (i.emissivit

# USER HAS TO SET THOSE
# QUIET REPORTS
QIET = True
# OVERWRITE EXISTING FILES
OVR = False
# Define Landsat 7 sensor for i.landsat.toar
LSENSOR = "tm7"

# Setup the path to the Landsat 7 Directories
rsdatapath = "~/rawData/L7Dir"
# set L7 Metadata wildcards
wldc_mtl = "*_MTL.txt"
# Visibility distance [Km]
vis = 18

# DEM input to atmospheric correction
inDEM = rsdatapath + "/dem_30m/Kenya_SRTM30meters.tif"

import glob
import os
import subprocess
import sys

# path to the GRASS GIS launch script
# MS Windows
# grass7bin_win = r'C:\OSGeo4W\bin\grass72svn.bat'
# uncomment when using standalone WinGRASS installer
# grass7bin_win = r'C:\Program Files (x86)\GRASS GIS 7.2.0\grass72.bat'
# Linux
grass7bin_lin = 'grass72'
# Mac OS X
# grass7bin_mac = '/Applications/GRASS/GRASS-7.2.app/'

# DATA
# define GRASS DATABASE
# add your path to grassdata (GRASS GIS database) directory
gisdb = os.path.join(os.path.expanduser("~"), "rawData")
# the following path is the default path on MS Windows
# gisdb = os.path.join(os.path.expanduser("~"), "Documents/grassdata")

# specify (existing) location and mapset
location = "L7_Kenya"
mapset = "hempire"

# SOFTWARE
if sys.platform.startswith('linux'):
    # we assume that the GRASS GIS start script is available and in the PATH
    # query GRASS 7 itself for its GISBASE
    grass7bin = grass7bin_lin
else:
    raise OSError('Platform not configured.')

# query GRASS 7 itself for its GISBASE
startcmd = [grass7bin, '--config', 'path']

p = subprocess.Popen(startcmd, shell=False,
                     stdout=subprocess.PIPE, stderr=subprocess.PIPE)
out, err = p.communicate()
if p.returncode != 0:
    print >> sys.stderr, "ERROR: Cannot find GRASS GIS 7 start script (%s)"
% startcmd
    sys.exit(-1)
gisbase = out.strip('\n\r')

# Set GISBASE environment variable
os.environ['GISBASE'] = gisbase
# the following not needed with trunk
os.environ['PATH'] += os.pathsep + os.path.join(gisbase, 'extrabin')
# add path to GRASS addons
home = os.path.expanduser("~")
os.environ['PATH'] += os.pathsep + os.path.join(home, '.grass7', 'addons',
'scripts')

# define GRASS-Python environment
gpydir = os.path.join(gisbase, "etc", "python")
sys.path.append(gpydir)

# DATA
# Set GISDBASE environment variable
os.environ['GISDBASE'] = gisdb

# import GRASS Python bindings (see also pygrass)
import grass.script.setup as gsetup

gsetup.init(gisbase, gisdb, location, mapset)
from grass.pygrass.modules.shortcuts import raster as r


# Needed for floor()


# env = os.environ.copy()
# env['GRASS_MESSAGE_FORMAT'] = 'gui'
# Function to get a list of L7 Directories in the rsdatapath
def fn(path):
    for top, dirs, files in os.walk(path):
        return [os.path.join(top, dir) for dir in dirs]


# START PROCESS
# PART 0: PRE-PROCESSING STUFF ###
# import DEM for atmospheric correction
# r.in.gdal(input=inDEM,output="dem",overwrite=OVR)
# r.mapcalc(expression="dem=25",overwrite=OVR)
# create a visibility map
# r.mapcalc(expression="vis=18", overwrite=OVR)
# Find the central location of the Landsat file from metadata
metadata = []
fileList = []
L7Dirs = fn(rsdatapath)
for L7Dir in L7Dirs:
    # Ungzip all of your Landsat7 images in all your directories
    # print "Ungzip Landsat files in\t",L7Dir
    # p=os.system("gzip -d -q "+L7Dir+"/*.gz")
    # Using pthreads on multi-core machines
    # p=os.system("pigz -d "+L7Dir+"/*.gz")
    # Wait ten seconds for gzip to create the tif images
    # time.sleep(10)
    print "Import in GRASS GIS"



Kind Regards,

*Joseph Kariuki*

*Geospatial Engineer** | **GIS / Web Developer*
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