Semantics-Augmented Set Abstraction (SASA)

By Chen Chen, Zhe Chen, Jing Zhang, and Dacheng Tao

This repository is the code release of the paper SASA: Semantics-Augmented Set Abstraction for Point-based 3D Object Detection, accepted by AAAI 2022.

Introduction

TL; DR. We develop a new set abstraction module named Semantics-Augmented Set Abstraction (SASA) for point-based 3D detectors. It could largely enhance the feature learning by helping extracted point representations better focus on meaningful foreground regions.

Abstract. Although point-based networks are demonstrated to be accurate for 3D point cloud modeling, they are still falling behind their voxel-based competitors in 3D detection. We observe that the prevailing set abstraction design for down-sampling points may maintain too much unimportant background information that can affect feature learning for detecting objects. To tackle this issue, we propose a novel set abstraction method named Semantics-Augmented Set Abstraction (SASA). Technically, we first add a binary segmentation module as the side output to help identify foreground points. Based on the estimated point-wise foreground scores, we then propose a semantics-guided point sampling algorithm to help retain more important foreground points during down-sampling. In practice, SASA shows to be effective in identifying valuable points related to foreground objects and improving feature learning for point-based 3D detection. Additionally, it is an easy-to-plug-in module and able to boost various point-based detectors, including single-stage and two-stage ones. Extensive experiments validate the superiority of SASA, lifting point-based detection models to reach comparable performance to state-of-the-art voxel-based methods.

Main Results

Here we present experimental results evaluated on the KITTI validation set and the corresponding pretrained models.

Method	Easy	Moderate	Hard	download
3DSSD	91.53	83.12	82.07	Google Drive
3DSSD + SASA	92.34	85.91	83.08	Google Drive
PointRCNN	91.80	82.35	80.21	Google Drive
PointRCNN + SASA	92.25	82.80	82.23	Google Drive

Getting Started

Requirements

Linux
Python >= 3.6
PyTorch >= 1.3
CUDA >= 9.0
CMake >= 3.13.2
spconv v1.2

Installation

a. Clone this repository.

git clone https://github.com/blakechen97/SASA.git
cd SASA

b. Install spconv library.

git clone https://github.com/traveller59/spconv.git
cd spconv
git checkout v1.2.1
git submodule update --init --recursive
python setup.py bdist_wheel
pip install ./dist/spconv-1.2.1-cp36-cp36m-linux_x86_64.whl   # wheel file name may be different
cd ..

c. Install pcdet toolbox.

pip install -r requirements.txt
python setup.py develop

Data Preparation

a. Prepare datasets.

SASA
├── data
│   ├── kitti
│   │   ├── ImageSets
│   │   ├── training
│   │   │   ├──calib & velodyne & label_2 & image_2 & (optional: planes)
│   │   ├── testing
│   │   ├── calib & velodyne & image_2
│   ├── nuscenes
│   │   ├── v1.0-trainval (or v1.0-mini if you use mini)
│   │   │   ├── samples
│   │   │   ├── sweeps
│   │   │   ├── maps
│   │   │   ├── v1.0-trainval  
├── pcdet
├── tools

b. Generate data infos.

# KITTI dataset
python -m pcdet.datasets.kitti.kitti_dataset create_kitti_infos tools/cfgs/dataset_configs/kitti_dataset.yaml

# nuScenes dataset
pip install nuscenes-devkit==1.0.5
python -m pcdet.datasets.nuscenes.nuscenes_dataset --func create_nuscenes_infos \ 
    --cfg_file tools/cfgs/dataset_configs/nuscenes_dataset.yaml \
    --version v1.0-trainval

Training

Train with a single GPU:

python train.py --cfg_file ${CONFIG_FILE}

Train with multiple GPUs:

sh scripts/dist_train.sh ${NUM_GPUS} --cfg_file ${CONFIG_FILE}

Testing

Test a pretrained model with a single GPU:

python test.py --cfg_file ${CONFIG_FILE} --ckpt ${CKPT}

Please check GETTING_STARTED.md to learn more usage of OpenPCDet.

Acknowledgement

This project is built with OpenPCDet (version 0.3), a powerful toolbox for LiDAR-based 3D object detection. Please refer to OpenPCDet.md and the official github repository for more information.

License

This project is released under the Apache 2.0 license.

Citation

If you find this project useful in your research, please consider cite:

@article{chen2022sasa,
  title={SASA: Semantics-Augmented Set Abstraction for Point-based 3D Object Detection},
  author={Chen, Chen and Chen, Zhe and Zhang, Jing and Tao, Dacheng},
  journal={arXiv preprint arXiv:2201.01976},
  year={2022}
}

blakechen97 / SASA