Unsupervised BatchNorm Adaptation (UBNA): A Domain Adaptation Method for Semantic Segmentation Without Using Source Domain Representations

Marvin Klingner, Jan-Aike Termöhlen, Jacob Ritterbach, and Tim Fingscheidt

Link to paper

Citation

If you find our work useful or interesting, please consider citing our paper:

@article{klingner2020unsupervised,
 title   = {{Unsupervised BatchNorm Adaptation (UBNA): A Domain Adaptation Method for Semantic Segmentation Without Using Source Domain Representations}},
 author  = {Marvin Klingner and
            Jan-Aike Term\"{o}hlen and
            Jacob Ritterbach and
            Tim Fingscheidt
           },
 year = {2020}
 archivePrefix = {arXiv},
 eprint = {2011.08502},
}

Getting Started

To run our code you need to go through the following steps:

1. Start a fresh conda environment and install the necessary packages as follows:

   • conda install pytorch=1.6 torchvision cudatoolkit=10.2 -c pytorch
   • pip install tensorboardX
   • pip install opencv-contrib-python
   • conda install -c conda-forge python-wget (just necessary for kitti download script)

2. Create a dataset folder where all the used datasets will be stored. Specify the environment variables UBNA_DIR_DATASET and UBNA_DIR_CHECKPOINT, leading to the paths of this dataset folder and the folder where the checkpoints are to be saved. Depending on your operating system, this can be done as follows:

   • Windows:

     setx UBNA_DIR_DATASET <PATH_TO_DATASET>
     setx UBNA_DIR_CHECKPOINT <PATH_TO_CHECKPOINTS>

   • Linux:

     export UBNA_DIR_DATASET=<PATH_TO_DATASET>
     export UBNA_DIR_CHECKPOINT=<PATH_TO_CHECKPOINTS>

3. To download the datasets, you can use the following steps. Note that you do not necessarily need all datasets for all experiments (e.g. for GTA to Cityscapes you only need gta-5 and Cityscapes and Cityscapes sequence datasets), but if you download all datasets mentioned here, you should be able to run all experiments described in the paper:

   • Cityscapes: Create a folder called cityscapes in your dataset folder. Go to https://www.cityscapes-dataset.com/downloads/, log in, download and unpack the following dataset parts into that folder:
     • leftImg8bit_trainvaltest.zip
     • gtFine_trainvaltest.zip
   • Cityscapes (sequences): Create a folder called cityscapes_sequence in your dataset folder. Go to https://www.cityscapes-dataset.com/downloads/, log in, download and unpack the following dataset parts into that folder:
     • leftImg8bit_sequence_trainvaltest.zip
   • SYNTHIA: Download the SYNTHIA dataset (SYNTHIA-RAND-CITYSCAPES) from https://synthia-dataset.net/downloads/ and rename the folder to synthia afterwards. Run the script in data_download/convert_segmentation_synthia.py to convert the labels to a nicer format.
   • GTA-5: Download all parts of the GTA-5 dataset from https://download.visinf.tu-darmstadt.de/data/from_games/. Put all color images in a subfolder images and all labels in a subfolder labels. Rename the main folder to gta5 afterwards.
   • GTA-5 (full split): Create an empty folder called gta5_full_split. It will be used later to store the split information for the GTA-5 dataset.
   • KITTI: You can use the script download_kitti.py in the data_download folder. It will automatically create a folder called kitti_download and download all necessary parts of the KITTI dataset. Please rename the folder to kitti afterwards.
   • KITTI (kitti split): Create an empty folder called kitti_kitti_split. It will be used later to store the split information for the KITTI dataset.
   • KITTI 2015:
     • Create a folder called kitti_2015. Download the stereo_2015/flow_2015/scene_flow_2015 dataset from http://www.cvlibs.net/datasets/kitti/eval_scene_flow.php into that folder.
     • Download the labels from http://www.cvlibs.net/datasets/kitti/eval_semseg.php?benchmark=semantics2015 and place them in the respective folders in the kitti_2015 directory.

4. Download the .json files from the following download links and place them in the dataset folders.

   • Cityscapes: https://drive.google.com/drive/folders/1E9RdGX-uAtrU1p_OLjOrVI4tKBdZwg6W?usp=sharing
   • Cityscapes (sequences): https://drive.google.com/drive/folders/1EKGfzjotMc8_R42nHaMmwIfyyv0W4Q42?usp=sharing
   • SYNTHIA: https://drive.google.com/drive/folders/11tzLxx7DvD0xrAyDpHpXIUGC62Xs14jI?usp=sharing
   • GTA-5: https://drive.google.com/drive/folders/1uv4iaOiJ0fbZOHcrTcmFLqje5WdXazPR?usp=sharing
   • GTA-5 (full split): https://drive.google.com/drive/folders/18t4Alb8jhk8Y7BqbxAAK9k8-Yqx1wxBE?usp=sharing
   • KITTI : https://drive.google.com/drive/folders/1i2n5SmKWmst0CenxUznUHZ0oxJzlBfS9?usp=sharing
   • KITTI (kitti split): https://drive.google.com/drive/folders/14ymxqZD1VeH1lBUbX6YwfivBI_mo2a0h?usp=sharing
   • KITTI 2015: https://drive.google.com/drive/folders/1ru77CfONBDwGmU0jwZnFUgrG8e9j6hEp?usp=sharing

   The resulting folder structure should look as follows.

   .
   ├── cityscapes
   │   ├── gtFine
   │   ├── leftImg8bit
   │   ├── basic_files.json
   │   ├── parameters.json
   │   ├── train.json
   │   ├── validation.json
   │   └── test.json
   │ 
   ├── cityscapes_sequence
   │   ├── leftImg8bit_sequence
   │   ├── basic_files.json
   │   ├── parameters.json
   │   ├── train.json
   │   ├── validation.json
   │   └── test.json
   │ 
   ├── synthia
   │   ├── RAND_CITYSCAPES
   │   ├── basic_files.json
   │   ├── parameters.json
   │   └── train.json
   │ 
   ├── gta5
   │   ├── images
   │   ├── labels
   │   ├── basic_files.json
   │   └── parameters.json
   │
   |── gta5_full_split
   |   └── train.json
   |
   ├── kitti
   │   ├── Raw_data
   │   ├── basic_files.json
   │   └── parameters.json
   │
   │── kitti_kitti_split
   │   ├── test.json
   │   ├── train.json
   │   └── validation.json
   │
   └── kitti_2015
       ├── training
       ├── testing
       ├── basic_files.json
       ├── parameters.json
       ├── test.json
       ├── train.json
       └── validation.json
   
   

Pretraining of the Semantic Segmentation Network

With this code example we demonstrate the adaptation from GTA-5 to Cityscapes as described in our paper. The commands for the other settings can be found in the experiments folder. The precedure, however, remains the same for all settings. For pretraining the semantic segmentation network, there is a train.py provided. There are different options available. For a full list see arguments.py. Our pretraining procedure is given by the following command and involves using only the weighted cross-entropy loss as described in the paper.

python3 train.py \
        --model-name ubna_pretrained_seg_gta_vgg16 \
        --model-type "vgg" \
        --model-num-layers-vgg 16 \
        --segmentation-training-loaders "gta5_train" \
        --segmentation-training-batch-size 12 \
        --experiment-class "ubna_pretrained_models"

You can of course also simply run the pretrain.sh shell script located in the experiments/gta_to_cs/ directory. The pretrained model will be saved in the folder ubna_pretrained_models within the directory you specified before with the environment variable UBNA_DIR_CHECKPOINT.

Download the pretrained baseline

Adaptation of the Network to the New Domain

For adaption of the network to the new domain using our UBNA-method, you can choose between the two approaches we introduced in our paper:

1) Batch-wise decaying BN-momentum (UBNA)

To adapt the network with batch-wise decaying BN-momentum (i.e., BN momentum is shrinking in dependency on the number of batches alreday used for adaptation), you may run the adapt_ubna.sh shell script in experiments/gta_to_cs, which you can find within the experiments directory. Our used setup is given by the command:

python3 adapt.py \
        --model-name ubna_adaption_gta_to_cs_vgg16_BS6_alpha_batch=0.08_alpha_layer=0 \
        --adaptation-training-loaders "cityscapes_sequence_train" \
        --adaptation-resize-width 1024 \
        --adaptation-resize-height 512 \
        --adaptation-training-batch-size 6 \
        --model-type "vgg" \
        --model-num-layers-vgg 16 \
        --model-load ubna_pretrained_models/ubna_pretrained_seg_gta_vgg16/checkpoints/epoch_20 \
        --model-disable-lr-loading \
        --experiment-class "ubna_adapted_models" \
        --adaptation-alpha-batch 0.08 \
        --adaptation-mode-sequential "batch_shrinking" \
        --adaptation-num-batches 50

Make sure that the model.pth file of the pretrained model is located in the folder ubna_pretrained_models/ubna_pretrained_seg_gta_vgg16/checkpoints/epoch_20 specified in the model-load argument.

Download the UBNA model

2) Additional layer-wise decaying BN-momentum (UBNA+)

For adapting the Network with an additional layer-wise decaying weighting factor, that is shrinking in dependency on the number of trained batches and additionally is set individually for each BN layer, run the shell script adapt_ubna_plus.sh, which you can find within the experiments/gta_to_cs directory. Our used setup is given by the command:

python3 adapt.py \
        --model-name ubna_adaption_gta_to_cs_vgg16_BS6_alpha_batch=0.08_alpha_layer=0.03 \
        --adaptation-training-loaders "cityscapes_sequence_train" \
        --adaptation-resize-width 1024 \
        --adaptation-resize-height 512 \
        --adaptation-training-batch-size 6 \
        --model-type "vgg" \
        --model-num-layers-vgg 16 \
        --model-load ubna_pretrained_models/ubna_pretrained_seg_gta_vgg16/checkpoints/epoch_20 \
        --model-disable-lr-loading \
        --experiment-class "ubna_adapted_models" \
        --adaptation-alpha-batch 0.08 \
        --adaptation-alpha-layer 0.03 \
        --adaptation-mode-sequential "layer_shrinking" \
        --adaptation-num-batches 50

In both cases, you can choose the number of adaptation steps using the argument adaptation-num-batches. After adaption, the model will be saved in the directory ubna_adapted_models within the directory you specified before with the environment variable UBNA_DIR_CHECKPOINT.

Download the UBNA+ model

Evaluation of the Network

For evaluation of the network, run the evaluate.sh shell script, which you can find within the experiments directory. Make sure that the correct path to the model files is specified in the parameter model_load as given in the below examples. Also note that the paths are defined relative to the UBNA_DIR_DATASET directory.

python3 eval_segmentation.py \
        --sys-best-effort-determinism \
        --model-type "vgg" \
        --model-name "eval_cs" \
        --model-load ubna_adapted_models/ubna_adaption_cs_to_kitti_vgg16_BS6_alpha_batch=0.08_alpha_layer=0.3/checkpoints/batch_50 \
        --segmentation-validation-loaders "cityscapes_validation"

Pre-Trained Models

Our provided models should meet the marks provided in the paper which you should be able to reproduce (up to a small margin, as the PyTorch framework is not deterministic during training):

Model	Cityscapes to KITTI	SYNTHIA to Cityscapes	GTA-5 to Cityscapes
Baseline	Download	Download	Download
UBNA	Download	Download	Download
UBNA+	Download	Download	Download

There is a small "Download" button at the top right

License

This code is licensed under the MIT-License feel free to use it within the boundaries of this license.