polsarpro.io

This code is part of the Python PolSARpro software:

"A re-implementation of selected PolSARPro functions in Python, following the scientific recommendations of PolInSAR 2021"

developed within an ESA funded project with SATIM.

Author: Olivier D'Hondt, 2025. Scientific advisors: Armando Marino and Eric Pottier.

Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

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Description: module containing read / write functions

get_incidence_angle_netcdf_beam(file_in, interpolation_method='linear')

Extract the incidence angle raster from a SNAP NetCDF-BEAM file.

Parameters:

Name	Type	Description	Default
file_in	str | Path	NetCDF-BEAM file produced with SNAP.	required
interpolation_method	str	interpolation method passed to xarray.Dataset.interp.	'linear'

Returns:

Type	Description
Dataset	xarray.Dataset: incidence angle interpolated to the raster grid.

Note

This is a helper function that interpolates incidence angle from the tie point grid to the raster grid in SLC products. For geocoded products this function is not relevant since various incidence angles can be directly computed with SNAP Range Doppler Terrain Correction.

open_netcdf_beam(file_path)

Open data in the NetCDF-BEAM format exported by SNAP and create a valid python PolSARpro Dataset. Also works for complex matrix datasets written with polmat_to_netcdf.

Parameters:

Name	Type	Description	Default
file_path	str | Path	path of the input file.	required

Returns:

Type	Description
Dataset	xarray.Dataset: output dataset with python PolSARpro specific metadata.

Note

Only polarimetric data is allowed. Supported polarimetric types are 'S' scattering matrix, 'C3' and 'C4' covariance matrices, 'T3' and 'T4' coherency matrices as well as 'C2' dual-polarimetric covariance matrix.

polmat_to_netcdf(ds, file_path)

Writes complex polarimetric matrices to a nectdf file. Due to the lack of complex number support in netcdf files, real and imaginary parts are stored separately. Variable names follow the netcdf-beam convention used by SNAP.

Parameters:

Name	Type	Description	Default
ds	Dataset	input dataset with polarimetric matrix elements.	required
file_path	str | Path	output file path.	required