i.sentinel1.gdargeocode - GRASS GIS manual

NAME

i.sentinel1.gdargeocode - Geocode Sentinel-1 data using the GDAR library

KEYWORDS

imagery, satellite, download, SAR, Sentinel

SYNOPSIS

i.sentinel1.gdargeocode

i.sentinel1.gdargeocode --help

i.sentinel1.gdargeocode [-ar] input=name elevation=name [output_directory=name] aoi=name [register_file=name] polarization=string[,string,...] mode=string scale=string suffix=string [overviews=integer[,integer,...]] [nprocs=integer] [--help] [--verbose] [--quiet] [--ui]

Flags:

-a: Apply precision orbit information if available
-r: Remove border noise
--help: Print usage summary
--verbose: Verbose module output
--quiet: Quiet module output
--ui: Force launching GUI dialog

Parameters:

input=name [required]: Path to input file(s); Comma separated list of paths to Sentinel-1 SAFE files or single text file with list of Sentinel-1 SAFE files (one path per row)
elevation=name [required]: Name of input elevation raster map
output_directory=name: Directory where to store geocoded Sentinel-1 data; Name for output directory where to store geocoded Sentinel-1 data (default: ./)
aoi=name [required]: Path to GeoJSON file with the Area Of Interest (aoi); Path to GeoJSON file with the Area Of Interest (aoi)
register_file=name: Path to register file for registering results in TGIS
polarization=string[,string,...] [required]: Currently only VV and VH from Sentinel-1 GRD IW are supported; Sentinel-1 polarization to geocode; Options: VV, VH; Default: VH
mode=string [required]: Currently only IW mode is supported for Sentinel-1; Sentinel-1 mode to geocode; Options: IW; Default: IW
scale=string [required]: Currently only dbi scaling is supported; Scaling applied to output values; Options: abs, intensity, dba, dbi; Default: dbi
suffix=string [required]: Suffix added to geocoded file / map names; Default: gec
overviews=integer[,integer,...]: Add overviews to resulting GeoTiffs (e.g. 2,3,8,16)
nprocs=integer: Number of threads for parallel computing; Default: 1

DESCRIPTION
EXAMPLES
REQUIREMENTS
REFERENCES
AUTHOR

DESCRIPTION

i.sentinel1.gdargeocode geocodes Sentinel-1 imagery on a user defined Digital Elevation Model (DEM) elevation using the proprietary GDAR library developed by (NORCE). Sentinel-1 images with Coordinate reference systems (CRS) different from the current LOCATION will be projected to the CRS of the LOCATION and results will be aligned with and resampled to the pixels in the input DEM.

i.sentinel1.gdargeocode requires a digital elevation model with ellipsoidal reference height as input in the elevation option. Usualy, elevation models represent geoidal heights. Users can apply an Earth Gravitational Model (EGM) to compute ellipsoidal heights from their geoidal elevation models. EGMs can be downloaded as GeoTiffs here: https://cdn.proj.org/ and added to the heights in the geoidal elevation model:

r.mapcalc expression="DTM_ellipsoidal=DTM+EGM"

Values in the output raster maps can be scaled in four different ways using the scale option:

abs: absolute values
intensity: absolute squared values
dba: dB absoulute values
dbi: dB intensity values

If the a-flag is set, a precise orbit file is fetched from ESAs web service if available (recommended). Note that there is usually a several days time lag after sensing time before these files are made available. If precise orbit files for the given scene are not available, the process will proceeed without and give a warning.

input can be a single Sentinel-1 SAFE file, a directory containing Sentinel-1 files, a comma separated list of Sentinel-1 files or a text file with a list of Sentinel-1 files to geocode. Geocoded images are stored in GeoTIFF format in the output_directory and linked to the GRASS GIS database using r.external.

If only a specifc extent of the Sentinel-1 images is supposed to be geocoded, the user can define the Area of Interest aoi in form of a GeoJSON with a single geometry.

In the nprocs option, users can specify the number of parallel process to run.

Currently, only geocoding of Sentinel-1 imagery in IW mode and VV or VH polarization is supported.

EXAMPLES

i.sentinel1.gdargeocode -a input=S1A_IW_GRDH_1SDV_20200304T161544_20200304T161609_031528_03A1CB_4A98.SAFE output_directory=./ elevation=elevation

REQUIREMENTS

i.sentinel1.gdargeocode uses the following non-standard Python libraries:

The proprietary GDAR Python library developed by NORCE (coming with own dependencies)
Python bindings for GDAL
the rasterio Python library

In order to make GRASS GIS Raster maps directly available to rasterio, the GDAL-GRASS plugin is required to.

REFERENCES

asf_search Basics

AUTHOR

Stefan Blumentrath

SOURCE CODE

Available at: i.sentinel1.gdargeocode source code (history)

Accessed: Monday Sep 16 09:38:03 2024