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Bridging the Gap between Events and Frames through Unsupervised Domain Adaptation

This is the code for the paper Bridging the Gap between Events and Frames through Unsupervised DomainAdaptation (PDF) by Nico Messikommer, Daniel Gehrig, Mathias Gehrig, and Davide Scaramuzza.

If you use any of this code, please cite the following publication:

@InProceedings{Messikommer20ral,
  author        = {Nico Messikommer and Daniel Gehrig and Mathias Gehrig and Davide Scaramuzza},
  title         = {Bridging the Gap between Events and Frames through Unsupervised Domain Adaptation},
  journal       = {Robotics and Automation Letters. (RA-L)},
  url           = {http://rpg.ifi.uzh.ch/docs/RAL22_Messikommer.pdf},
  year          = 2022
}

Abstract

Reliable perception during fast motion maneuvers or in high dynamic range environments is crucial for robotic systems. Since event cameras are robust to these challenging conditions, they have great potential to increase the reliability of robot vision. However, event-based vision has been held back by the shortage of labeled datasets due to the novelty of event cameras. To overcome this drawback, we propose a task transfer method to train models directly with labeled images and unlabeled event data. Compared to previous approaches, (i) our method transfers from single images to events instead of high frame rate videos, and (ii) does not rely on paired sensor data. To achieve this, we leverage the generative event model to split event features into content and motion features. This split enables efficient matching between latent spaces for events and images, which is crucial for successful task transfer. Thus, our approach unlocks the vast amount of existing image datasets for the training of event-based neural networks. Our task transfer method consistently outperforms methods targeting Unsupervised Domain Adaptation for object detection by 0.26 mAP (increase by 93%) and classification by 2.7% accuracy.

Installation

Dependencies

If desired, a conda environment can be created using the followig command:

conda create -n <env_name>

As an initial step, the wheel package needs to be installed with the following command:

pip install wheel

The required python packages are listed in the requirements.txt file.

pip install -r requirements.txt

To convert the MVSEC or the One Megapixel dataset to the hdf5 format, the following compression package needs to be installed: https://github.com/conda-forge/blosc-hdf5-plugin-feedstock

To use the Waymo Open Dataset, the following package needs to be installed: https://github.com/gdlg/simple-waymo-open-dataset-reader

Datasets

Caltech101 and N-Caltech101

The paired dataset containing Caltech101 and N-Caltech101 can be downloaded here The dataset should have the following format:

├── N-Caltech101                 # Path in settings.yaml is the directory of this folder
│   ├── accordion                # Classes as folder names
│   │   ├── cam0_events_0001.npy 
│   └── ...
├── Caltech101
│   ├── accordion
│   │   ├── image_0001.jpg
│   └── ...
├── split_train_0.5_val_0.25_test_0.25_new
│   ├── test.txt
│   ├── train.txt
│   └── val.txt
├── split_train_0.5_val_0.25_test_0.25_new_extended
│   ├── test.txt
│   ├── train.txt
│   └── val.txt

As our method does not require paired frame and event data, the extened caltech101 can be used. Thus, the splits in the split_train_0.5_val_0.25_test_0.25_new_extended directory are used by default.

The training splits defined in <mode>.txt should have the following content, where the number corresponds to the sample id in the specific class:

accordion:
- 3
- 10
...

MVSEC

The MVSEC dataset can be downloaded here. Before training, the MVSEC dataset should be converted to hdf5, which can be done with the datasets/export_data_from_rosbag.py script. The command to run the script can be found at the top of the script.

The MVSEC labels can be downloaded from the following repository: https://github.com/alexzzhu/EventGAN.

The labels should be placed in the directory of the corresponding sequence:

├── <sequence_name> 
│   ├── processed_data.hdf5
│   └── labels
│   │   ├── 00000396.txt
│   │   ├── <frame_id>.txt
│   │   ├── ....

The text file should have the following format:

Class Not Specified y_min, x_min, y_max, x_max

If necessary, the dataloader needs to be adapted according the labels provided by the EventGAN authors.

Waymo

The Waymo Open Dataset can be downloaded here.

One Megapixel Dataset

The One Megapixel Dataset can be downloaded here. To use the provided dataloader, the dataset should be converted to hdf5, which can be done with the datasets/convert_oneMP_dataset.py script. The compressed data can directly be converted to hdf5 by the following bash script in datasets/decompress_convert_oneMP_dataset.sh. The file paths should be adjusted in the bash script.

Training

The settings for the training should be specified in config/settings.yaml. To start the training, it is necessary to replace <path> everywhere in the yaml file. If the dataset is not used, the path can also be replaced by None.

Two different models can be trained:

classification_model: standard transfer model for the classification task
object_det_model: transfer model for the object detection task

The following command starts the training:

CUDA_VISIBLE_DEVICES=<GPU_ID>, python train.py --settings_file config/settings.yaml

Acknowledgement

Several network architectures were adapted from: https://github.com/HsinYingLee/DRIT

The general training framework was inspired by: https://github.com/alexzzhu/EventGAN

The object detection network was adapted from: https://github.com/eriklindernoren/PyTorch-YOLOv3/

The mvsec extraction script was adapted from: https://github.com/SensorsINI/ECCV_network_grafting_algorithm

The optimizer was adapted from: https://github.com/LiyuanLucasLiu/RAdam

The ssim loss was adapted from: https://github.com/Po-Hsun-Su/pytorch-ssim