Current state-of-the-art approaches for spatio-temporal action localization rely on detections at the frame level and model temporal context with 3D ConvNets. Here, we go one step further and model spatio-temporal relations to capture the interactions between human actors, relevant objects and scene elements essential to differentiate similar human actions. Our approach is weakly supervised and mines the relevant elements automatically with an actor-centric relational network (ACRN). ACRN computes and accumulates pair-wise relation information from actor and global scene features, and generates relation features for action classification. It is implemented as neural networks and can be trained jointly with an existing action detection system. We show that ACRN outperforms alternative approaches which capture relation information, and that the proposed framework improves upon the state-of-the-art performance on JHMDB and AVA. A visualization of the learned relation features confirms that our approach is able to attend to the relevant relations for each action.
1. The **gpus** indicates the number of gpu we used to get the checkpoint.
According to the [Linear Scaling Rule](https://arxiv.org/abs/1706.02677), you may set the learning rate proportional to the batch size if you use different GPUs or videos per GPU,
e.g., lr=0.01 for 4 GPUs x 2 video/gpu and lr=0.08 for 16 GPUs x 4 video/gpu.
:::
For more details on data preparation, you can refer to AVA in [Data Preparation](/docs/data_preparation.md).
## Train
You can use the following command to train a model.
For more details and optional arguments infos, you can refer to **Training setting** part in [getting_started](/docs/getting_started.md#training-setting).
## Test
You can use the following command to test a model.
For more details and optional arguments infos, you can refer to **Test a dataset** part in [getting_started](/docs/getting_started.md#test-a-dataset) .
## Citation
<!-- [DATASET] -->
```BibTeX
@inproceedings{gu2018ava,
title={Ava: A video dataset of spatio-temporally localized atomic visual actions},
author={Gu, Chunhui and Sun, Chen and Ross, David A and Vondrick, Carl and Pantofaru, Caroline and Li, Yeqing and Vijayanarasimhan, Sudheendra and Toderici, George and Ricco, Susanna and Sukthankar, Rahul and others},
booktitle={Proceedings of the IEEE Conference on Computer Vision and Pattern Recognition},
pages={6047--6056},
year={2018}
}
```
```BibTeX
@inproceedings{sun2018actor,
title={Actor-centric relation network},
author={Sun, Chen and Shrivastava, Abhinav and Vondrick, Carl and Murphy, Kevin and Sukthankar, Rahul and Schmid, Cordelia},
booktitle={Proceedings of the European Conference on Computer Vision (ECCV)},
title={Ava: A video dataset of spatio-temporally localized atomic visual actions},
author={Gu, Chunhui and Sun, Chen and Ross, David A and Vondrick, Carl and Pantofaru, Caroline and Li, Yeqing and Vijayanarasimhan, Sudheendra and Toderici, George and Ricco, Susanna and Sukthankar, Rahul and others},
booktitle={Proceedings of the IEEE Conference on Computer Vision and Pattern Recognition},
pages={6047--6056},
year={2018}
}
```
<!-- [ALGORITHM] -->
```BibTeX
@inproceedings{sun2018actor,
title={Actor-centric relation network},
author={Sun, Chen and Shrivastava, Abhinav and Vondrick, Carl and Murphy, Kevin and Sukthankar, Rahul and Schmid, Cordelia},
booktitle={Proceedings of the European Conference on Computer Vision (ECCV)},
Training Json Log:https://download.openmmlab.com/mmaction/detection/acrn/slowfast_acrn_kinetics_pretrained_r50_8x8x1_cosine_10e_ava_rgb/slowfast_acrn_kinetics_pretrained_r50_8x8x1_cosine_10e_ava_rgb.json
Training Log:https://download.openmmlab.com/mmaction/detection/acrn/slowfast_acrn_kinetics_pretrained_r50_8x8x1_cosine_10e_ava_rgb/slowfast_acrn_kinetics_pretrained_r50_8x8x1_cosine_10e_ava_rgb.log
Training Json Log:https://download.openmmlab.com/mmaction/detection/acrn/slowfast_acrn_kinetics_pretrained_r50_8x8x1_cosine_10e_ava22_rgb/slowfast_acrn_kinetics_pretrained_r50_8x8x1_cosine_10e_ava22_rgb.json
Training Log:https://download.openmmlab.com/mmaction/detection/acrn/slowfast_acrn_kinetics_pretrained_r50_8x8x1_cosine_10e_ava22_rgb/slowfast_acrn_kinetics_pretrained_r50_8x8x1_cosine_10e_ava22_rgb.log
[Ava: A video dataset of spatio-temporally localized atomic visual actions](https://openaccess.thecvf.com/content_cvpr_2018/html/Gu_AVA_A_Video_CVPR_2018_paper.html)
This paper introduces a video dataset of spatio-temporally localized Atomic Visual Actions (AVA). The AVA dataset densely annotates 80 atomic visual actions in 430 15-minute video clips, where actions are localized in space and time, resulting in 1.58M action labels with multiple labels per person occurring frequently. The key characteristics of our dataset are: (1) the definition of atomic visual actions, rather than composite actions; (2) precise spatio-temporal annotations with possibly multiple annotations for each person; (3) exhaustive annotation of these atomic actions over 15-minute video clips; (4) people temporally linked across consecutive segments; and (5) using movies to gather a varied set of action representations. This departs from existing datasets for spatio-temporal action recognition, which typically provide sparse annotations for composite actions in short video clips. We will release the dataset publicly.
AVA, with its realistic scene and action complexity, exposes the intrinsic difficulty of action recognition. To benchmark this, we present a novel approach for action localization that builds upon the current state-of-the-art methods, and demonstrates better performance on JHMDB and UCF101-24 categories. While setting a new state of the art on existing datasets, the overall results on AVA are low at 15.6% mAP, underscoring the need for developing new approaches for video understanding.
1. The **gpus** indicates the number of gpu we used to get the checkpoint.
According to the [Linear Scaling Rule](https://arxiv.org/abs/1706.02677), you may set the learning rate proportional to the batch size if you use different GPUs or videos per GPU,
e.g., lr=0.01 for 4 GPUs x 2 video/gpu and lr=0.08 for 16 GPUs x 4 video/gpu.
2.**Context** indicates that using both RoI feature and global pooled feature for classification, which leads to around 1% mAP improvement in general.
:::
For more details on data preparation, you can refer to AVA in [Data Preparation](/docs/data_preparation.md).
## Train
You can use the following command to train a model.
For more details and optional arguments infos, you can refer to **Training setting** part in [getting_started](/docs/getting_started.md#training-setting) .
### Train Custom Classes From Ava Dataset
You can train custom classes from ava. Ava suffers from class imbalance. There are more then 100,000 samples for classes like `stand`/`listen to (a person)`/`talk to (e.g., self, a person, a group)`/`watch (a person)`, whereas half of all classes has less than 500 samples. In most cases, training custom classes with fewer samples only will lead to better results.
Three steps to train custom classes:
- Step 1: Select custom classes from original classes, named `custom_classes`. Class `0` should not be selected since it is reserved for further usage (to identify whether a proposal is positive or negative, not implemented yet) and will be added automatically.
- Step 2: Set `num_classes`. In order to be compatible with current codes, Please make sure `num_classes == len(custom_classes) + 1`.
- The new class `0` corresponds to original class `0`. The new class `i`(i > 0) corresponds to original class `custom_classes[i-1]`.
- There are three `num_classes` in ava config, `model -> roi_head -> bbox_head -> num_classes`, `data -> train -> num_classes` and `data -> val -> num_classes`.
- If `num_classes <= 5`, input arg `topk` of `BBoxHeadAVA` should be modified. The default value of `topk` is `(3, 5)`, and all elements of `topk` must be smaller than `num_classes`.
- Step 3: Make sure all custom classes are in `label_file`. It is worth mentioning that there are two label files, `ava_action_list_v2.1_for_activitynet_2018.pbtxt`(contains 60 classes, 20 classes are missing) and `ava_action_list_v2.1.pbtxt`(contains all 80 classes).
Take `slowonly_kinetics_pretrained_r50_4x16x1_20e_ava_rgb` as an example, training custom classes with AP in range `(0.1, 0.3)`, aka `[3, 6, 10, 27, 29, 38, 41, 48, 51, 53, 54, 59, 61, 64, 70, 72]`. Please note that, the previously mentioned AP is calculated by original ckpt, which is trained by all 80 classes. The results are listed as follows.
For more details and optional arguments infos, you can refer to **Test a dataset** part in [getting_started](/docs/getting_started.md#test-a-dataset) .
## Citation
<!-- [DATASET] -->
```BibTeX
@inproceedings{gu2018ava,
title={Ava: A video dataset of spatio-temporally localized atomic visual actions},
author={Gu, Chunhui and Sun, Chen and Ross, David A and Vondrick, Carl and Pantofaru, Caroline and Li, Yeqing and Vijayanarasimhan, Sudheendra and Toderici, George and Ricco, Susanna and Sukthankar, Rahul and others},
booktitle={Proceedings of the IEEE Conference on Computer Vision and Pattern Recognition},
pages={6047--6056},
year={2018}
}
```
```BibTeX
@article{duan2020omni,
title={Omni-sourced Webly-supervised Learning for Video Recognition},
author={Duan, Haodong and Zhao, Yue and Xiong, Yuanjun and Liu, Wentao and Lin, Dahua},
title={Ava: A video dataset of spatio-temporally localized atomic visual actions},
author={Gu, Chunhui and Sun, Chen and Ross, David A and Vondrick, Carl and Pantofaru, Caroline and Li, Yeqing and Vijayanarasimhan, Sudheendra and Toderici, George and Ricco, Susanna and Sukthankar, Rahul and others},
booktitle={Proceedings of the IEEE Conference on Computer Vision and Pattern Recognition},
pages={6047--6056},
year={2018}
}
```
<!-- [ALGORITHM] -->
```BibTeX
@article{duan2020omni,
title={Omni-sourced Webly-supervised Learning for Video Recognition},
author={Duan, Haodong and Zhao, Yue and Xiong, Yuanjun and Liu, Wentao and Lin, Dahua},
journal={arXiv preprint arXiv:2003.13042},
year={2020}
}
```
<!-- [ALGORITHM] -->
```BibTeX
@inproceedings{feichtenhofer2019slowfast,
title={Slowfast networks for video recognition},
author={Feichtenhofer, Christoph and Fan, Haoqi and Malik, Jitendra and He, Kaiming},
booktitle={Proceedings of the IEEE international conference on computer vision},
用户可以训练 AVA 数据集中的自定义类别。AVA 中不同类别的样本量很不平衡：其中有超过 100000 样本的类别： `stand`/`listen to (a person)`/`talk to (e.g., self, a person, a group)`/`watch (a person)`，也有样本较少的类别（半数类别不足 500 样本）。大多数情况下，仅使用样本较少的类别进行训练将在这些类别上得到更好精度。
