LiDARTouch: Monocular metric depth estimation with a few-beam LiDAR

This is the reference PyTorch implementation for training and testing depth prediction models using the method described in our paper LiDARTouch: Monocular metric depth estimation with a few-beam LiDAR

If you find our work useful, please consider citing:

@misc{bartoccioni2021lidartouch,
    title={LiDARTouch: Monocular metric depth estimation with a few-beam LiDAR},
    author={Florent Bartoccioni and Éloi Zablocki and Patrick Pérez and Matthieu Cord and Karteek Alahari},
    year={2021},
    eprint={2109.03569},
    archivePrefix={arXiv},
    primaryClass={cs.CV}
}

⚙ Setup

Environment

First, clone the repo

# clone project   
git clone https://github.com/F-Barto/LiDARTouch
cd LiDARTouch

Then, create the conda environment, install dependencies and activate env.

# create conda env and install dependancies 
conda env create -n LiDARTouch -f environment.yaml
conda activate LiDARTouch
pip install -e .

💾 Data-preparation

To train the model from scratch on KITTI you first need to download both:

• the raw data
• the depth completion data

⚠️the data weighs about 200GB

Once the data downloaded you need to preprocess it. ℹ️Note that we provide the data split files under data_splits

Under the scripts/kitti_data_preparation folder you will find:

• lidar_sparsification.py
• prepare_split_data.py

Step 1: LiDAR sparsification

This script virtually sparsify the raw 64-beam LiDAR to a 4-beam LiDAR; use as follows:

python lidar_sparsification.py KITTI_RAW_ROOT_DIR OUTPUT_DIR DATA_SPLIT_DIR SPLIT_FILE_NAMES [OPTIONS]

e.g.,

python ./lidar_sparsification.py \
/path_to_kitti_root_folder/KITTI_raw/  \
/path_to_sparfied_lidar_data/sparsified_lidar/ \
/path_to_LiDARTouch_folder/LiDARTouch/data_splits \
'eigen_train_files.txt,filtered_eigen_val_files.txt,filtered_eigen_test_files.txt' \
--downsample_factor=16

the parameter --downsample_factor=16 indicates that only 1 out of 16 beams will be kept (leading to 4 beam). Alternatively, you can choose to select individual beams by their indexes with --downsample_indexes='5,7,9,11,20.

Step 2: Temporal context and Pose pre-computation

Then we will create a pickle split_data containing the data for:

• the source views available for each image listed in the split file
• the relative pose between the source and target views using the IMU and/or Perspective-n-point w/ LiDAR

This script is used as follows:

prepare_split_data.py KITTI_RAW_ROOT_DIR OUTPUT_PATH DATA_SPLIT_DIR SPLIT_FILE_NAMES SOURCE_VIEWS_INDEXES [OPTIONS]

e.g.,

python ./prepare_split_data.py \
/path_to_kitti_root_folder/KITTI_raw/  \
/path_to_output/split_data.pkl \
/path_to_LiDARTouch_folder/LiDARTouch/data_splits \
'eigen_train_files.txt,filtered_eigen_val_files.txt,filtered_eigen_test_files.txt' \
'[-1,1]' \
--imu \
--pnp /path_to_sparfied_lidar_data/sparsified_lidar/factor_16

use --help for more details.

Step 3: Paths configuration

Copy and rename the file .env_example to .env. Change the paths present in the .env file to configure the saving dir, the paths to your dataset and the pre-processed data.

🏋️ Training

Monodepth2 depth network only photometric supervision (relative depth | infinite depth issue)

python train.py experiment=PoseNet_P_multiscale depth_net=monodepth2

Monodepth2 depth network with IMU supervision (metric depth | infinite depth issue)

python train.py experiment=PoseNet_P+IMU_multiscale depth_net=monodepth2

Monodepth2-L depth network with LiDARTouch supervision (metric depth | NO infinite depth issue)

python train.py experiment=PnP_P+ml1L4_multiscale depth_net=monodepth2lidar

Regarding the infinite depth problem, the two major factors alleviating it are the auto-masking and the LiDAR self-supervision. In practice, we found multi-scale supervision and the smoothness loss to be critical for stable training when using the LiDAR self-supervision.

🎖️ Acknowledgements

This work and code base is based upon the papers and code base of:

• PackNet-sfm
• Monodepth2
• Selfsup Sparse-to-Dense

In particular, to structure our code we used:

Please consider giving these projects a star or citing their work if you use them.