STHN: Deep Homography Estimation for UAV Thermal Geo-localization with Satellite Imagery

This is the official repository for STHN: Deep Homography Estimation for UAV Thermal Geo-localization with Satellite Imagery.

Related works:

• STHN: Deep Homography Estimation for UAV Thermal Geo-localization with Satellite Imagery [Project]

@ARTICLE{xiao2024sthn,
  author={Xiao, Jiuhong and Zhang, Ning and Tortei, Daniel and Loianno, Giuseppe},
  journal={IEEE Robotics and Automation Letters}, 
  title={STHN: Deep Homography Estimation for UAV Thermal Geo-Localization With Satellite Imagery}, 
  year={2024},
  volume={9},
  number={10},
  pages={8754-8761},
  keywords={Estimation;Location awareness;Satellites;Satellite images;Autonomous aerial vehicles;Accuracy;Iterative methods;Deep learning for visual perception;aerial systems: applications;localization},
  doi={10.1109/LRA.2024.3448129}}

Developer: Jiuhong Xiao
Affiliation: NYU ARPL
Maintainer: Jiuhong Xiao (jx1190@nyu.edu)

Dataset

We extend the Boson-nighttime dataset from STGL with additional unpaired satellite images and our generated thermal images using TGM.

Dataset link (122 GB): Download

The datasets folder should be created in the root folder with the following structure. By default, the dataset uses $W_S=512$, while the larger suffix indicates $W_S=1536$.

STHN/datasets/
├── maps
│   └── satellite
|   |   └── 20201117_BingSatellite.png
├── satellite_0_satellite_0
│   └── train_database.h5
├── satellite_0_thermalmapping_135
│   ├── test_database.h5
│   ├── test_queries.h5
│   ├── train_database.h5
│   ├── train_queries.h5
│   ├── val_database.h5
│   └── val_queries.h5
├── satellite_0_thermalmapping_135_train
│   ├── extended_database.h5 -> ../satellite_0_satellite_0/train_database.h5
│   ├── extended_queries.h5
│   ├── test_database.h5 -> ../satellite_0_thermalmapping_135/test_database.h5
│   ├── test_queries.h5 -> ../satellite_0_thermalmapping_135/test_queries.h5
│   ├── train_database.h5 -> ../satellite_0_thermalmapping_135/train_database.h5
│   ├── train_queries.h5 -> ../satellite_0_thermalmapping_135/train_queries.h5
│   ├── val_database.h5 -> ../satellite_0_thermalmapping_135/val_database.h5
│   └── val_queries.h5 -> ../satellite_0_thermalmapping_135/val_queries.h5

Conda Environment Setup

Our repository requires a conda environment. Relevant packages are listed in env.yml. Run the following command to setup the conda environment.

conda env create -f env.yml

Training

You can find the training scripts and evaluation scripts in scripts folder. The scripts is for slurm system to submit sbatch job. If you want to run bash command, change the suffix from sbatch to sh and run with bash.

Coarse-level Alignment Training

To train the coarse-level alignment module, use one of the scripts in ./scripts/local for $W_S=512$ and ./scripts/local_larger for $W_S=1536$ with different $D_C$, for example:

./scripts/local_larger/train_local_sparse_512_extended_long.sbatch

After training, find your model folder in ./logs/local_he/$dataset_name-$datetime-$uuid
The $dataset_name-$datetime-$uuid is your coarse_model_folder_name.

Refinement Training (only for $W_S=1536$)

Before training, change the restore_ckpt argument using coarse_model_folder_name to load your trained coarse-level alignment module.

To train the refinement module, use one of the scripts in ./scripts/local_larger_2 per name, for example:

./scripts/local/train_local_sparse_512_extended_long_load_f_aug64_c.sbatch

After training, find your model folder in ./logs/local_he/$dataset_name-$datetime-$uuid
The $dataset_name-$datetime-$uuid is your refine_model_folder_name.

Evaluation

To evaluate one-stage and two-stage methods, use one of the following scripts:

./scripts/local/eval.sbatch
./scripts/local_larger/eval.sbatch
./scripts/local_larger_2/eval_local_sparse_512_extended.sbatch

Find the test results in ./test/local_he/$model_folder_name/.
⚠️ Please note that the MACE and CE tests are performed on resized images with dimensions of 256x256. To convert these metrics from pixels to meters, you need to multiply them by a scaling factor, denoted as $\alpha$. This can be expressed as $MACE(m) = \alpha \cdot MACE(pixel)$. Specifically, use $\alpha = 6$ when $W_S = 1536$, and $\alpha = 2$ when $W_S = 512$.

Image-matching Baselines

For training and evaluating the image-matching baselines (anyloc and STGL), please refer to scripts/global/ for training and evaluation.

Pretrained Models

Download pretrained TGM and STHN models for $W_S=1536$ and $D_C=512$ m: Download

Additional Details

Train/Val/Test split

Below is the visualization of the train-validation-test regions. The dataset includes thermal maps from six flights: three flights (conducted at 9 PM, 12 AM, and 2 AM) cover the upper region, and the other three flights (conducted at 10 PM, 1 AM, and 3 AM) cover the lower region. The lower region is further divided into training and validation subsets. The synthesized thermal images span a larger area (23,744m x 9,088m) but exclude the test region to assess generalization performance properly.

Architecture Details

The feature extractor consists of multiple residual blocks with multi-layer CNN and group normalization:

STHN/local_pipeline/extractor.py

Line 177 in 0ad04d7

class BasicEncoderQuarter(nn.Module):

The iterative updater is a multi-layer CNN with group normalization:

STHN/local_pipeline/update.py

Line 299 in eed553f

class GMA(nn.Module):

The TGM is using the Pix2Pix paradigm:

STHN/global_pipeline/model/network.py

Line 273 in eed553f

class pix2pix():

Direct Linear Transformation Details

The Direct Linear Transformation (DLT) is used to solve the homography transformation matrix (3x3) given four corresponding point pairs.

In practice, we use kornia's implementation:
https://kornia.readthedocs.io/en/stable/geometry.transform.html#kornia.geometry.transform.get_perspective_transform
For more details of formulas, you can refer to: https://en.wikipedia.org/wiki/Direct_linear_transformation.

Acknowledgement

Our implementation refers to the following repositories and appreciate their excellent work.

https://github.com/imdumpl78/IHN
https://github.com/AnyLoc/AnyLoc
https://github.com/gmberton/deep-visual-geo-localization-benchmark
https://github.com/fungtion/DANN
https://github.com/junyanz/pytorch-CycleGAN-and-pix2pix