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Detection in Crowded Scenes: One Proposal, Multiple Predictions

This is the pytorch re-implementation of the paper "Detection in Crowded Scenes: One Proposal, Multiple Predictions" that published in CVPR 2020.

Object detection in crowded scenes is challenging. When objects gather, they tend to overlap largely with each other, leading to occlusions. Occlusion caused by objects of the same class is called intra-class occlusion, also referred to as crowd occlusion. Object detectors need to determine the locations of different objects in the crowd and accurately delineate their boundaries. Many cases are quite challenging even for human annotators.

To address the aforementioned problem, this paper proposed a schema that one anchor/proposal can predict multiple predictions simultaneously. With this scheme, the predictions of nearby proposals are expected to infer the same set of instances, rather than distinguishing individuals, which is much easy for the model to learn. Besides, A new NMS method called set NMS is designed to remove the duplicates during the inference time. The EMD loss is devised to obtain the minimal loss during optimization based on the truth that a set of combinations can be obtained between the predictions and groundtruth boxes. Therefore, the combination that produces the minimal loss can be chosen to better optimize the model during training. Additionally, the proposed schema can be deployed on the mainstream detectors such as Cascade RCNN, FPN and also one-stage detector RetinaNet. The implementation details can be viewed in the repository.

The model structure and results are shown here:

Citation

If you use the code in your research, please cite:

@InProceedings{Chu_2020_CVPR,
author = {Chu, Xuangeng and Zheng, Anlin and Zhang, Xiangyu and Sun, Jian},
title = {Detection in Crowded Scenes: One Proposal, Multiple Predictions},
booktitle = {Proceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR)},
month = {June},
year = {2020}
}

Run

1. Requirements:

   • python 3.6.8, pytorch 1.5.0, torchvision 0.6.0, cuda 10.1

2. CrowdHuman data:

   • CrowdHuman is a benchmark dataset containing highly overlapped objects to better evaluate whether a detector can better handle crowd scenarios. The dataset can be downloaded from http://www.crowdhuman.org/. The path of the dataset is set in config.py.

3. Steps to run:

   • Step1: training. More training and testing settings can be set in config.py.

   cd ROOT_DIR/model/DETECTOR_NAME/OWNER_NAME/project
   

   • Step2: testing. If you have four GPUs, you can use -d 0-NUM_GPUS to use all of your GPUs. NUM_GPUS is the number of GPUs you would lik to use during inference, The result json file will be saved in the corresponding directory automatically.

   cd ROOT_DIR/model/DETECTOR_NAME/OWNER_NAME/project
   python3 test_net.py -d 0-NUM_GPUS -r 40 -e 50
   

   • Step3: evaluating json, inference one picture and visulization json file. All of the value correpsponding the different evalutation metric will be calculated and be saved in a log file

   cd ROOT_DIR/model/DETECTOR_NAME/OWNER_NAME/project
   python3 demo.py
   

Models

This proiect is a re-implementation based on Pytorch. We use pre-trained model from MegEngine Model Hub and convert this model to pytorch. You can get this model from GoogleDrive or Baidu Netdisk(code:yx46).

All models are re-trained based on ResNet-50.