Usage
Configuration
Usage of the S1_NRB package relies on a configuration file that needs to be set up by the user. The configuration
file follows the INI format, which uses plain text to store properties as key-value pairs. INI files can be created and
opened with any text editor. An example config.ini
file for the S1_NRB package can be found here:
https://github.com/SAR-ARD/S1_NRB/blob/main/config.ini
The following provides an overview of the parameters the config.ini
should contain and anything that should be
considered when selecting their values:
mode
Options: all | nrb | snap
This parameter determines if the entire processing chain should be executed or only part of it.
aoi_tiles & aoi_geometry
The area of interest (AOI) for which S1-NRB products should be created.
aoi_tiles
can be used to define the area of interest via MGRS tile IDs, which must be provided comma-separated (e.g.,
aoi_tiles = 32TNS, 32TMT, 32TMS
). aoi_geometry
defines the area of interest via a full path to a vector file
supported by spatialist.vector.Vector
. This option will automatically search for overlapping MGRS tiles and use
these for processing.
Both parameters are optional and can be set to None
or left empty. aoi_tiles
overrides aoi_geometry
.
If neither is defined, all tiles overlapping with the scene search result are processed.
mindate & maxdate
The time period to create S1-NRB products for. Allowed date formats are %Y-%m-%d
and %Y-%m-%dT%H:%M:%S
.
acq_mode
Options: IW | EW | SM
The acquisition mode of the source scenes that should be processed.
product
Options: GRD | SLC
The product of the source scenes that should be processed.
work_dir & scene_dir
Both need to be provided as full paths to existing directories. work_dir
is the main directory in which any
subdirectories and files are stored that are generated during processing. scene_dir
will be searched recursively for
any Sentinel-1 scenes using the regex pattern '^S1[AB].*\.zip$'
.
rtc_dir, tmp_dir, nrb_dir, wbm_dir & log_dir
Processing S1-NRB products creates many intermediate files that are expected to be stored in separate subdirectories. The
default values provided in the example configuration file linked above are recommended and will automatically create
subdirectories relative to the directory specified with work_dir
. E.g., nrb_dir = NRB
will create the subdirectory
/<work_dir>/NRB
. Optionally, full paths to existing directories can be provided for all of these parameters.
db_file
Any Sentinel-1 scenes found in scene_dir
will be stored in a database file created by pyrosar.drivers.Archive
.
With db_file
either a full path to an existing database can be provided or it will be created in work_dir
if only
a filename is provided. E.g., db_file = scenes.db
will automatically create the database file /<work_dir>/scenes.db
.
kml_file
The Sentinel-2 Military Grid Reference System (MGRS) tiling system establishes the basis of the processing chain and a
local reference file containing the respective tile information for processing S1-NRB products is needed. The official
KML file provided by ESA can be retrieved here.
With the kml_file
parameter either a full path to this reference file can be provided or it is expected to be located
in the directory provided with work_dir
if only a filename is provided. E.g., the processor expects to find
/<work_dir>/s2_grid.kml
if kml_file = s2_grid.kml
.
dem_type
Options: Copernicus 10m EEA DEM | Copernicus 30m Global DEM II | Copernicus 30m Global DEM | GETASSE30
The Digital Elevation Model (DEM) that should be used for processing.
Note that water body masks are not available for “GETASSE30”, and will therefore not be included in the product data mask. “Copernicus 10m EEA DEM” and “Copernicus 30m Global DEM II” (both include water body masks) are retrieved from the Copernicus Space Component Data Access system (CSCDA), which requires registration. The processor reads username and password from the environment variables DEM_USER and DEM_PASS if possible and otherwise interactively asks for authentication if one of these DEM options is selected.
gdal_threads
Temporarily changes GDAL_NUM_THREADS during processing. Will be reset after processing has finished.
measurement
Options: gamma | sigma
The backscatter measurement convention. Either creates gamma naught RTC (\(\gamma^0_T\)) or ellipsoidal sigma naught (\(\sigma^0_E\)).
annotation
A comma-separated list to define the annotation layers to be created. Supported options:
dm: data mask (four masks: not layover not shadow, layover, shadow, ocean water)
ei: ellipsoidal incident angle (needed for computing geolocation accuracy)
em: digital elevation model
id: acquisition ID image (source scene ID per pixel)
lc: RTC local contributing area
li: local incident angle
np: noise power (NESZ, per polarization)
gs: gamma-sigma ratio: sigma0 RTC / gamma0 RTC (ignored if
measurement
is not gamma)sg: sigma-gamma ratio: gamma0 RTC / sigma0 ellipsoidal (ignored if
measurement
is not sigma)
Use one of the following to create no annotation layer:
annotation =
annotation = None
etad & etad_dir
Determines if the Extended Timing Annotation Dataset (ETAD) correction
should be performed or not. If etad=True
, etad_dir
is searched for ETAD products matching the respective input SLC
and a new SLC is created in tmp_dir
, which is then used for all other processing steps. If etad=False
, etad_dir
will be ignored.
Sections
Configuration files in INI format can have different sections. Each section begins at a section name and ends at the next
section name. The config.ini
file used with the S1_NRB package should at least have a dedicated section for processing
related parameters. This section is by default named [PROCESSING]
(see example config file).
A reserved section [METADATA]
may contain user-specific metadata to be written to the product’s metadata files.
Currently supported fields:
access_url
licence
doi
processing_center
Users might create several processing sections in the same configuration file with parameter values that correspond to different processing scenarios (e.g., for different areas of interest). Note that each section must contain all necessary configuration parameters even if only a few are varied between the sections.
Command Line Interface
Once a configuration file has been created and all of its parameters have been properly defined, it can be used to start the processor using the command line interface (CLI) tool provided with the S1_NRB package.
The following options are currently available:
s1_nrb --help
Print a help message for the CLI tool.
s1_nrb --version
Print the processor version.
s1_nrb -c /path/to/config.ini
Start the processor using parameters defined in the default section of a config.ini
file.
s1_nrb -c /path/to/config.ini -s SECTION_NAME
Start the processor using parameters defined in section SECTION_NAME
of a config.ini
file.