A Transformer-Based Siamese Network for Change Detection

Wele Gedara Chaminda Bandara, and Vishal M. Patel

Presented at IGARSS-22, Kuala Lumpur, Malaysia.

Useful links:

• Paper (published): https://ieeexplore.ieee.org/document/9883686
• Paper (ArXiv): https://arxiv.org/abs/2201.01293
• Presentation (in YouTube): https://www.youtube.com/watch?v=SkiNoTrSmQM

• Change Detection with Denoising Diffusion Probabilistic Models: DDPM-CD
• Semi-supervised Change Detection: SemiCD
• Unsupervised Change Detection: Metric-CD

Python 3.8.0
pytorch 1.10.1
torchvision 0.11.2
einops  0.3.2

• Please see requirements.txt for all the other requirements.

Create a virtual conda environment named ChangeFormer with the following command:

conda create --name ChangeFormer --file requirements.txt
conda activate ChangeFormer

Clone this repo:

git clone https://github.com/wgcban/ChangeFormer.git
cd ChangeFormer

We have some samples from the LEVIR-CD dataset in the folder samples_LEVIR for a quick start.

Firstly, you can download our ChangeFormerV6 pretrained model——by Github-LEVIR-Pretrained.

Place it in checkpoints/ChangeFormer_LEVIR/.

Run a demo to get started as follows:

python demo_LEVIR.py

You can find the prediction results in samples/predict_LEVIR.

We have some samples from the DSIFN-CD dataset in the folder samples_DSIFN for a quick start.

Download our ChangeFormerV6 pretrained model——by Github. After downloaded the pretrained model, you can put it in checkpoints/ChangeFormer_DSIFN/.

Run the demo to get started as follows:

python demo_DSIFN.py

You can find the prediction results in samples/predict_DSIFN.

When we initialy train our ChangeFormer, we initialized some parameters of the network with a model pre-trained on the RGB segmentation (ADE 160k dataset) to get faster convergence.

You can download the pre-trained model Github-LEVIR-Pretrained.

wget https://www.dropbox.com/s/undtrlxiz7bkag5/pretrained_changeformer.pt

Then, update the path to the pre-trained model by updating the path argument in the run_ChangeFormer_LEVIR.sh. Here:

You can find the training script run_ChangeFormer_LEVIR.sh in the folder scripts. You can run the script file by sh scripts/run_ChangeFormer_LEVIR.sh in the command environment.

The detailed script file run_ChangeFormer_LEVIR.sh is as follows:

#!/usr/bin/env bash

#GPUs
gpus=0

#Set paths
checkpoint_root=/media/lidan/ssd2/ChangeFormer/checkpoints
vis_root=/media/lidan/ssd2/ChangeFormer/vis
data_name=LEVIR


img_size=256    
batch_size=16   
lr=0.0001         
max_epochs=200
embed_dim=256

net_G=ChangeFormerV6        #ChangeFormerV6 is the finalized verion

lr_policy=linear
optimizer=adamw                 #Choices: sgd (set lr to 0.01), adam, adamw
loss=ce                         #Choices: ce, fl (Focal Loss), miou
multi_scale_train=True
multi_scale_infer=False
shuffle_AB=False

#Initializing from pretrained weights
pretrain=/media/lidan/ssd2/ChangeFormer/pretrained_segformer/segformer.b2.512x512.ade.160k.pth

#Train and Validation splits
split=train         #train
split_val=test      #test, val
project_name=CD_${net_G}_${data_name}_b${batch_size}_lr${lr}_${optimizer}_${split}_${split_val}_${max_epochs}_${lr_policy}_${loss}_multi_train_${multi_scale_train}_multi_infer_${multi_scale_infer}_shuffle_AB_${shuffle_AB}_embed_dim_${embed_dim}

CUDA_VISIBLE_DEVICES=1 python main_cd.py --img_size ${img_size} --loss ${loss} --checkpoint_root ${checkpoint_root} --vis_root ${vis_root} --lr_policy ${lr_policy} --optimizer ${optimizer} --pretrain ${pretrain} --split ${split} --split_val ${split_val} --net_G ${net_G} --multi_scale_train ${multi_scale_train} --multi_scale_infer ${multi_scale_infer} --gpu_ids ${gpus} --max_epochs ${max_epochs} --project_name ${project_name} --batch_size ${batch_size} --shuffle_AB ${shuffle_AB} --data_name ${data_name}  --lr ${lr} --embed_dim ${embed_dim}

Follow the similar procedure mentioned for LEVIR-CD. Use run_ChangeFormer_DSIFN.sh in scripts folder to train on DSIFN-CD.

You can find the evaluation script eval_ChangeFormer_LEVIR.sh in the folder scripts. You can run the script file by sh scripts/eval_ChangeFormer_LEVIR.sh in the command environment.

The detailed script file eval_ChangeFormer_LEVIR.sh is as follows:

#!/usr/bin/env bash

gpus=0

data_name=LEVIR
net_G=ChangeFormerV6 #This is the best version
split=test
vis_root=/media/lidan/ssd2/ChangeFormer/vis
project_name=CD_ChangeFormerV6_LEVIR_b16_lr0.0001_adamw_train_test_200_linear_ce_multi_train_True_multi_infer_False_shuffle_AB_False_embed_dim_256
checkpoints_root=/media/lidan/ssd2/ChangeFormer/checkpoints
checkpoint_name=best_ckpt.pt
img_size=256
embed_dim=256 #Make sure to change the embedding dim (best and default = 256)

CUDA_VISIBLE_DEVICES=0 python eval_cd.py --split ${split} --net_G ${net_G} --embed_dim ${embed_dim} --img_size ${img_size} --vis_root ${vis_root} --checkpoints_root ${checkpoints_root} --checkpoint_name ${checkpoint_name} --gpu_ids ${gpus} --project_name ${project_name} --data_name ${data_name}

Follow the same evaluation procedure mentioned for LEVIR-CD. You can find the evaluation script eval_ChangeFormer_DSFIN.sh in the folder scripts. You can run the script file by sh scripts/eval_ChangeFormer_DSIFN.sh in the command environment.

Change detection data set with pixel-level binary labels；
├─A
├─B
├─label
└─list

A: images of t1 phase;

B:images of t2 phase;

label: label maps;

list: contains train.txt, val.txt and test.txt, each file records the image names (XXX.png) in the change detection dataset.

You can download the processed LEVIR-CD and DSIFN-CD datasets by the DropBox through the following here:

• LEVIR-CD-256: click here to download
• DSIFN-CD-256: click here to download

Since the file sizes are large, I recommed to use command line and cosider downloading the zip file as follows (in linux):

To download LEVIR-CD dataset run following command in linux-terminal:

wget https://www.dropbox.com/s/18fb5jo0npu5evm/LEVIR-CD256.zip

To download DSIFN-CD dataset run following command in linux-terminal:

wget https://www.dropbox.com/s/18fb5jo0npu5evm/LEVIR-CD256.zip

For your reference, I have also attached the inks to original LEVIR-CD and DSIFN-CD here: LEVIR-CD and DSIFN-CD.

If you wish to use ChangeFormer for multi-class change detection, you will need to make a few modifications to the existing codebase, which is designed for binary change detection. There are many discussions in the issues section. The required modifications are (#93 (comment)):

1. run_ChangeFormer_cd.sh: n_class=8 and make it a hyperparameter to python main.py
2. models/networks.py: net = ChangeFormerV6(embed_dim=args.embed_dim, output_nc=args.n_class)
3. models/basic_model.py: Comment out: pred_vis = pred * 255, i.e., modifications to visualisation processing
4. models/trainer.py: Modify: ConfuseMatrixMeter(n_class=self.n_class)

Code is released for non-commercial and research purposes only. For commercial purposes, please contact the authors.

If you use this code for your research, please cite our paper:

@INPROCEEDINGS{9883686,
  author={Bandara, Wele Gedara Chaminda and Patel, Vishal M.},
  booktitle={IGARSS 2022 - 2022 IEEE International Geoscience and Remote Sensing Symposium}, 
  title={A Transformer-Based Siamese Network for Change Detection}, 
  year={2022},
  volume={},
  number={},
  pages={207-210},
  doi={10.1109/IGARSS46834.2022.9883686}}

Appreciate the work from the following repositories:

• https://github.com/justchenhao/BIT_CD (Our ChangeFormer is implemented on the code provided in this repository)