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|
|30||B1, B2, B3, B4, B5, B7||B1, B2, B3, B4, B5, B7||B1, B2, B3, B4, B5, B6, B7, B9|
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.
i.landsat.import -p input=data
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
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