This is a despeckling-filter for TerraSAR-X images based on convolutional networks. The code only contains the inference (application) part, not the training.

This is an initial test of applying the speckle2speckle deep learning approach to TerraSAR-X images. The filter has been trained on TerraSAR-X images of Colima volcano (Mexico) only.

In case of questions contact:

• Andreas Ley ([email protected])
• Sébastien Valade ([email protected])

If you use this in a publication, please consider citing us (see section Credits below).

Teaser image showing crops of a TerraSAR-X image before and after filtering (the image captures Popocatépetl volcano in Mexico, and is published in the Supplementary Material of Valade et al. 2023 (Nature Communications)):

The code is CPU only and thus does not need a GPU or associated drivers. It does, however, need AVX extensions which should be present in every x86(_64) cpu from the last decade. If in doubt, check with:

cat /proc/cpuinfo | grep avx

The code is very much self contained and only needs an OpenMP capable C/C++ compiler and libTiff. A cmake file for building is also provided.

Install the following dependencies:

• gcc
• cmake
• libtiff (development packages)

E.g. for ubuntu:

sudo apt install gcc cmake libtiff5-dev

Or on fedora:

sudo dnf install gcc cmake libtiff-devel

Create a subdirectory for an out-of-source build:

mkdir buildRelease
cd buildRelease

Run cmake:

cmake .. -DCMAKE_BUILD_TYPE=Release

Build:

make -j 8

This should build an executable "applicationCPU" in the "buildRelease" directory.

The program ingests a (geo-)tiff image which must be the complex valued hh component in radar coordinates. Usually this is stored as two 16-bit integer values. The program can also ingest other data types (e.g. floats) but the value range/scaling must be the same.

The program outputs the filtered log-intensity values as a tiff image with float values which is intended for further processing. For visualization purposes it also outputs 8-bit images of the input and output. These are only intended for visualization and are not to be used for further processing. If you base your research on low quality 8-bit images with arbitrary tonemapping, you have none to blame but yourself!

The program takes two arguments. The filename of the source tiff image and a prefix for the output. Running it like so:

./applicationCPU /path/to/Popo/track_136_ASC_spot_090_20190425_004720.tif Popo_track_136_ASC_spot_090_20190425_004720

will produce these three files:

• Popo_track_136_ASC_spot_090_20190425_004720.tif -- Filtered log intensity output
• Popo_track_136_ASC_spot_090_20190425_004720_before.tif -- Visualization of input image
• Popo_track_136_ASC_spot_090_20190425_004720_after.tif -- Visualization of output image

TerraSAR-X raw products used for training were provided by the German Aerospace Center (DLR) to Prof. Thomas R. Walter (GFZ-Potsdam), under the project TSX-ID 1505.

The filter (version 1.0) was developed as part of the publication by Valade et al. (2023):
Valade S., Coppola D., Campion R., Ley A., Boulesteix T., Taquet N., Legrand D., Laiolo M., Walter T. R., De la Cruz-Reyna S. (2023) "Lava dome cycles reveal rise and fall of magma column at popocatépetl volcano", Nature Communications, doi: 10.1038/s41467-023-38386-9

The code version used in the publication is archived on Zenodo and citable as:
Ley, A. & Valade, S. (2023) "Andreas-Ley/S2S-TSX-Colima: Version v1.0.4", doi: 10.5281/zenodo.7838864.

Speckle2Speckle based despeckling filter for TerraSAR-X Spotlight mode
Copyright (C) 2020  Andreas Ley <[email protected]>

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <https://www.gnu.org/licenses/>.