ELASTIC

This repo contains the original PyTorch implementation of Elastic introduced in the following paper

ELASTIC: Improving CNNs with Dynamic Scaling Policies (CVPR 2019, Oral)

Huiyu Wang, Aniruddha Kembhavi, Ali Farhadi, Alan Yuille, and Mohammad Rastegari

It is compatible with PyTorch 1.0-stable, PyTorch 1.0-preview and PyTorch 0.4.1. All released models are exactly the models evaluated in the paper.

Contents

• ImageNet Classification
• MSCOCO Multi-label Classification
• PASCAL VOC Semantic Segmentation

ImageNet Classification

We prepare our data following https://github.com/pytorch/examples/tree/master/imagenet

Pretrained models available at

for a in resnext50 resnext50_elastic resnext101 resnext101_elastic dla60x dla60x_elastic dla102x se_resnext50_elastic densenet201 densenet201_elastic; do
   wget http://ai2-vision.s3.amazonaws.com/elastic/imagenet_models/"$a".pth.tar
done

Testing

python classify.py /path/to/imagenet/ --evaluate --resume /path/to/model.pth.tar

Training

python classify.py /path/to/imagenet/

Multi-processing distributed training in Docker (recommended):

We train all the models in docker containers: https://docs.nvidia.com/deeplearning/dgx/pytorch-release-notes/rel_18.07.html

You may need to follow instructions in the link above to install docker and nvidia-docker if you haven't done so.

After pulling the docker image, we run a docker container:

nvidia-docker run -it -e NVIDIA_VISIBLE_DEVICES=0,1 --ipc=host --rm -v /path/to/code:/path/to/code -v /path/to/imagenet:/path/to/imagenet nvcr.io/nvidia/pytorch:18.07-py3

Then run this training script inside the docker container.

python -m apex.parallel.multiproc docker_classify.py /path/to/imagenet

MSCOCO Multi-label Classification

We extract data into this structure and use python cocoapi to load data: https://github.com/cocodataset/cocoapi

/path/to/mscoco/annotations/instances_train2014.json
/path/to/mscoco/annotations/instances_val2014.json
/path/to/mscoco/train2014
/path/to/mscoco/val2014

Pretrained models available at

for a in resnext50 resnext50_elastic resnext101 resnext101_elastic dla60x dla60x_elastic densenet201 densenet201_elastic; do
   wget http://ai2-vision.s3.amazonaws.com/elastic/coco_models/coco_"$a".pth.tar
done

Testing

python multilabel_classify.py /path/to/mscoco --resume /path/to/model.pth.tar --evaluate

Finetuning or resume training

python multilabel_classify.py /path/to/mscoco --resume /path/to/model.pth.tar

PASCAL VOC Semantic Segmentation

We prepare PASCAL VOC data following https://github.com/chenxi116/DeepLabv3.pytorch

Pretrained models available at

for a in resnext50 resnext50_elastic resnext101 resnext101_elastic dla60x dla60x_elastic; do
   wget http://ai2-vision.s3.amazonaws.com/elastic/pascal_models/deeplab_"$a"_pascal_v3_original_epoch50.pth
done

Testing

Models should be put at data/deeplab_*.pth

CUDA_VISIBLE_DEVICES=0 python segment.py --exp original

Finetuning or resume training

All PASCAL VOC semantic segmentation models are trained on one GPU.

CUDA_VISIBLE_DEVICES=0 python segment.py --exp my_exp --train --resume /path/to/model.pth.tar

Note

Distributed training maintains batchnorm statistics on each GPU/worker/process without synchronization, which leads to different performances on different GPUs. At the end of each epoch, our distributed script reports averaged performance (top-1, top-5) by evaluating the whole validation set on all GPUs, and saves the model on the first GPU (throws away models on other GPUs). As a result, evaluating the saved model after training leads to slightly (<0.1%) different (could be either better or worse) numbers. In the paper, we reported the average performances for all models. Averaging batchnorm statistics before evaluation may lead to marginally better numbers.

Citation

Please consider citing this paper if you find this project useful in your research.

@article{wang2019elastic,
  title={ELASTIC: Improving CNNs with Dynamic Scaling Policies},
  author={Huiyu Wang, Aniruddha Kembhavi, Ali Farhadi, Alan Yuille, Mohammad Rastegari},
  journal={The IEEE Conference on Computer Vision and Pattern Recognition (CVPR)},
  year={2019}
}

Credits

• ImageNet training script is modified from https://github.com/pytorch/pytorch
• ImageNet distributed training script is modified from https://github.com/NVIDIA/apex
• Pascal segmentation code is modified from https://github.com/chenxi116/DeepLabv3.pytorch
• ResNext model is modified form https://github.com/last-one/tools
• DLA models are modified from https://github.com/ucbdrive/dla
• DenseNet model is modified from https://github.com/csrhddlam/pytorch-checkpoint