Official source code of TimeMatch: Unsupervised Cross-region Adaptation by Temporal Shift Estimation by Joachim Nyborg, Charlotte Pelletier, Sébastien Lefèvre, and Ira Assent.

The recent developments of deep learning models that capture complex temporal patterns of crop phenology have greatly advanced crop classification from Satellite Image Time Series (SITS). However, when applied to target regions spatially different from the training region, these models perform poorly without any target labels due to the temporal shift of crop phenology between regions. Although various unsupervised domain adaptation techniques have been proposed in recent years, no method explicitly learns the temporal shift of SITS and thus provide only limited benefits for crop classification. To address this, we propose TimeMatch, which explicitly accounts for the temporal shift for improved SITS-based domain adaptation. In TimeMatch, we first estimate the temporal shift from the target to the source region using the predictions of a source-trained model. Then, we re-train the model for the target region by an iterative algorithm where the estimated shift is used to generate accurate target pseudo-labels. Additionally, we introduce an open-access dataset for cross-region adaptation from SITS in four different regions in Europe. On our dataset, we demonstrate that TimeMatch outperforms all competing methods by 11% in average F1-score across five different adaptation scenarios, setting a new state-of-the-artin cross-region adaptation.

• Python 3.9.4, PyTorch 1.8.1, and more in environment.yml.

The dataset can be freely downloaded from Zenodo. The extracted size is about 78 GB.

Pre-trained models and results can also be downloaded from Zenodo

Setup conda environment and activate

conda env create -f environment.yml
conda activate timematch

Download dataset and extract to /media/data/timematch_data (or set --data_root to its path for train.py).

Pre-trained models should be extracted to timematch/outputs.

Example: train model on the source domain

python train.py -e pseltae_32VNH --source denmark/32VNH/2017 --target denmark/32VNH/2017

Train TimeMatch with pre-trained model

python train.py -e timematch_32VNH_to_30TXT --source denmark/32VNH/2017 --target france/30TXT/2017 timematch --weights outputs/pseltae_32VNH

All training scripts can be found in the scripts directory.

If you find TimeMatch or the code useful, please consider citing our paper using the following BibTeX entry.

@article{nyborg2022timematch,
  title={TimeMatch: Unsupervised cross-region adaptation by temporal shift estimation},
  author={Nyborg, Joachim and Pelletier, Charlotte and Lef{\`e}vre, S{\'e}bastien and Assent, Ira},
  journal={ISPRS Journal of Photogrammetry and Remote Sensing},
  volume={188},
  pages={301--313},
  year={2022},
  publisher={Elsevier}
}

• The implementation of PSE+LTAE is based on the official implementation
• The implementation of competitors MMD, DANN, and CDAN is based on Transfer Learning Library, and JUMBOT on its official implementation.
• The annotations used in the TimeMatch dataset from the LPIS produced by the mapping agencies IGN (France), NaturErhverstyrelsen (Denmark), and the AMA (Austria).
• The Sentinel-2 imagery were accessed from the AWS bucket managed by Sinergise