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NAME

i.landsat.import - Imports Landsat satellite data downloaded using i.landsat.download.

KEYWORDS

imagery, satellite, Landsat, import

SYNOPSIS

i.landsat.import
i.landsat.import --help
i.landsat.import [-rlop] input=name [unzip_dir=name] [pattern=string] [pattern_file=string] [extent=string] [resample=string] [memory=integer] [register_output=name] [--overwrite] [--help] [--verbose] [--quiet] [--ui]

Flags:

-r
Reproject raster data using r.import if needed
-l
Link raster data instead of importing
-o
Override projection check (use current location's projection)
-p
Print raster data to be imported and exit
--overwrite
Allow output files to overwrite existing files
--help
Print usage summary
--verbose
Verbose module output
--quiet
Quiet module output
--ui
Force launching GUI dialog

Parameters:

input=name [required]
Name of input directory with downloaded Landsat data
unzip_dir=name
Name of directory into which Landsat zip-files are extracted (default=input)
pattern=string
Band name pattern to import
pattern_file=string
File name pattern to import
extent=string
Output raster map extent
Options: input, region
Default: input
input: extent of input map
region: extent of current region
resample=string
Resampling method to use for reprojection
Options: nearest, bilinear, bicubic, lanczos, bilinear_f, bicubic_f, lanczos_f
Default: nearest
nearest: nearest neighbor
bilinear: bilinear interpolation
bicubic: bicubic interpolation
lanczos: lanczos filter
bilinear_f: bilinear interpolation with fallback
bicubic_f: bicubic interpolation with fallback
lanczos_f: lanczos filter with fallback
memory=integer
Maximum memory to be used (in MB)
Cache size for raster rows
Default: 300
register_output=name
Name for output file to use with t.register

Table of contents

DESCRIPTION

The i.landsat.import module allows importing Landsat 5, 7 and 8 products downloaded by the i.landsat.download module.

By default i.landsat.import imports all Landsat bands within the scene files found in the input directory. The number of scene files can be optionally reduced with the pattern_file option. In this option, a regular expression for filtering the file names can be given, e.g. '229083' for importing only scenes from path 229 and row 083.

By default i.landsat.import imports the full scene. Optionally, the import can be reduced to the computational region extent with extent=region.

Note that in case that the spatial reference system of the input data differs from that of the GRASS GIS target location, the input data will be reprojected internally by means of r.import. To speed up this process, a higher than default value can be specified for the memory option.

If the user wants to ignore an insignificant mismatch in the spatial reference system, the projection check can be suppressed with the -o flag and data will be imported directly.

Alternatively, input data can be linked by means of r.external using -l flag. Note that linking data requires that Landsat input data and GRASS location have the same spatial reference system (e.g., the same UTM zone). Take into account that USGS provides all Landsat products in UTM north zones whether they belong to North or South Hemisphere.

The number of Landsat bands to be imported can be optionally reduced by the pattern option. Below an overview of Landsat 5 TM, 7 ETM and 8 OLI band's spatial resolution:

Spatial resolution [m] L5 Bands L7 Bands L8 Bands
15 -- B8 B8
30 B1, B2, B3, B4, B5, B7 B1, B2, B3, B4, B5, B7 B1, B2, B3, B4, B5, B6, B7, B9
60 -- B6 --
100 -- -- B10, B11
120 B6 -- --

Note that while the original resolution of band 6 in Landsat 5 TM and Landsat 7 ETM is 120 and 60 m respectively, they are provided with a resampled resolution of 30 m. For further details about bands wavelength and scene size, visit the band designations page at USGS website.

The file naming convention for Landsat scenes is found here.

With the register_output option i.landsat.import allows to create a text file that can be used to register imported imagery data into a space-time raster dateset (STRDS) by means of t.register. A register file typically contains 2 or 3 columns with the map name and start time or the map name plus start and end time in the case of interval time type. Landsat data is considered to be of instance time type, i.e., we only have one point in time. Hence, the output register file will contain the map name and start time separated by | when using GRASS GIS stable version. In the case of GRASS GIS development version which supports the band reference concept (see g.bands module for details), the output register file is extended by a third column containing the band reference information, see the examples below.

EXAMPLES

List Landsat bands to import

At first, print the list of raster files to be imported by -p. For each file also projection match with current location is printed including detected input data EPSG code:
i.landsat.import -p input=data

Import Landsat data

Limit import to only 4th and 5th bands:
i.landsat.import input=data pattern='B(4|5)'

Limit import to all bands with 30m resolution:

i.landsat.import input=data pattern='B(1|2|3|4|5|6|7|9)'

Link Landsat data:

i.landsat.import -l input=data

Link data from specific path and row while ignoring projection check

i.landsat.import -l -o input=data pattern_file='229083'

Limit import to bands 4 and 5 for path 229 and row 083 in 2019

i.landsat.import input=data pattern_file='229083_2019' pattern='B(4|5)'

Limit import to bands 4 and 5 for path 229 and row 083 in 2019 and get a txt file to use in t.register

i.landsat.import input=data pattern_file='229083_2019' pattern='B(4|5)' \
    register_output=t_register.txt

# create a STRDS and register imported data
t.create output=landsat_ts title="Landsat 8 time series" \
    description="Landsat 8 data, path-row 229-83, year 2020"
t.register input=landsat_ts file=t_register.txt

SEE ALSO

Overview of i.landsat tools

i.landsat.download, i.landsat.qa, i.landsat.toar, i.landsat8.swlst, r.import, r.external

AUTHOR

Veronica Andreo, CONICET, Argentina.

SOURCE CODE

Available at: i.landsat.import source code (history)


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