ESL: Entropy-guided Self-supervised Learning for Domain Adaptation in Semantic Segmentation
Antoine Saporta, Tuan-Hung Vu, Matthieu Cord, Patrick Pérez
valeo.ai, France
IEEE Conference on Computer Vision and Pattern Recognition (CVPR) Workshop on Scalability in Autonomous Driving, 2020

If you find this code useful for your research, please cite our paper:

@misc{saporta2020esl,
    title={ESL: Entropy-guided Self-supervised Learning for Domain Adaptation in Semantic Segmentation},
    author={Antoine Saporta and Tuan-Hung Vu and Matthieu Cord and Patrick P{\'e}rez},
    year={2020},
    eprint={2006.08658},
    archivePrefix={arXiv},
    primaryClass={cs.CV}
}

While fully-supervised deep learning yields good models for urban scene semantic segmentation, these models struggle to generalize to new environments with different lighting or weather conditions for instance. In addition, producing the extensive pixel-level annotations that the task requires comes at a great cost. Unsupervised domain adaptation (UDA) is one approach that tries to address these issues in order to make such systems more scalable. In particular, self-supervised learning (SSL) has recently become an effective strategy for UDA in semantic segmentation. At the core of such methods lies `pseudo-labeling', that is, the practice of assigning high-confident class predictions as pseudo-labels, subsequently used as true labels, for target data. To collect pseudo-labels, previous works often rely on the highest softmax score, which we here argue as an unfavorable confidence measurement. In this work, we propose Entropy-guided Self-supervised Learning (ESL), leveraging entropy as the confidence indicator for producing more accurate pseudo-labels. On different UDA benchmarks, ESL consistently outperforms strong SSL baselines and achieves state-of-the-art results.

• Python 3.7
• Pytorch >= 0.4.1
• CUDA 9.0 or higher

0. Clone the repo:

$ git clone https://github.com/valeoai/ESL
$ cd ESL

1. Install OpenCV if you don't already have it:

$ conda install -c menpo opencv

2. Install this repository and the dependencies using pip:

$ pip install -e <root_dir>

With this, you can edit the ESL code on the fly and import function and classes of ESL in other project as well.

3. Optional. To uninstall this package, run:

$ pip uninstall ESL

You can take a look at the Dockerfile if you are uncertain about steps to install this project.

By default, the datasets are put in <root_dir>/data. We use symlinks to hook the ESL codebase to the datasets. An alternative option is to explicitlly specify the parameters DATA_DIRECTORY_SOURCE and DATA_DIRECTORY_TARGET in YML configuration files.

• GTA5: Please follow the instructions here to download images and semantic segmentation annotations. The GTA5 dataset directory should have this basic structure:

<root_dir>/data/GTA5/                               % GTA dataset root
<root_dir>/data/GTA5/images/                        % GTA images
<root_dir>/data/GTA5/labels/                        % Semantic segmentation labels
...

• Cityscapes: Please follow the instructions in Cityscape to download the images and validation ground-truths. The Cityscapes dataset directory should have this basic structure:

<root_dir>/data/Cityscapes/                         % Cityscapes dataset root
<root_dir>/data/Cityscapes/leftImg8bit              % Cityscapes images
<root_dir>/data/Cityscapes/leftImg8bit/val
<root_dir>/data/Cityscapes/gtFine                   % Semantic segmentation labels
<root_dir>/data/Cityscapes/gtFine/val
...

Pre-trained models can be downloaded here and put in <root_dir>/pretrained_models

For evaluation, execute:

$ cd <root_dir>/advent/scripts
$ python test.py --cfg ./configs/advent_pretrained.yml

For the experiments done in the paper, we used pytorch 0.4.1 and CUDA 9.0. To ensure reproduction, the random seed has been fixed in the code. Still, you may need to train a few times to reach the comparable performance.

By default, logs and snapshots are stored in <root_dir>/experiments with this structure:

<root_dir>/experiments/logs
<root_dir>/experiments/snapshots

To train AdvEnt:

$ cd <root_dir>/advent/scripts
$ python train.py --cfg ./configs/advent.yml

To generate ESL pseudo-labels:

$ cd <root_dir>/advent/scripts
$ python esl.py --cfg ./configs/esl.yml

To train AdvEnt with previously generated ESL pseudo-labels:

$ cd <root_dir>/advent/scripts
$ python train.py --cfg ./configs/esl.yml

To test AdvEnt:

$ cd <root_dir>/advent/scripts
$ python test.py --cfg ./configs/advent.yml

To test AdvEnt trained with ESL pseudo-labels:

$ cd <root_dir>/advent/scripts
$ python test.py --cfg ./configs/esl.yml

This codebase is heavily borrowed from AdvEnt and BDL.