Awesome

ShadowSense

Unsupervised Domain Adaptation and Feature Fusion for Shadow-Agnostic Tree Crown Detection from RGB-Thermal Drone Imagery

This is the official code repository for the paper titled above, accepted into the main conference at WACV 2024!

Two ways to access the paper:

• CVF open access
• ArXiv pre-print version

Abstract: Accurate detection of individual tree crowns from remote sensing data poses a significant challenge due to the dense nature of forest canopy and the presence of diverse environmental variations, e.g., overlapping canopies, occlusions, and varying lighting conditions. Additionally, the lack of data for training robust models adds another limitation in effectively studying complex forest conditions. This paper presents a novel method for detecting shadowed tree crowns and provides a challenging dataset comprising roughly 50k paired RGB-thermal images to facilitate future research for illumination-invariant detection. The proposed method (ShadowSense) is entirely self-supervised, leveraging domain adversarial training without source domain annotations for feature extraction and foreground feature alignment for feature pyramid networks to adapt domain-invariant representations by focusing on visible foreground regions, respectively. It then fuses complementary information of both modalities to effectively improve upon the predictions of an RGB-trained detector and boost the overall accuracy. Extensive experiments demonstrate the superiority of the proposed method over both the baseline RGB-trained detector and state-of-the-art techniques that rely on unsupervised domain adaptation or early image fusion.

Running on your own machine

1. Clone and enter repository

   git clone https://github.com/rudrakshkapil/ShadowSense
   cd ShadowSense
   

2. Create a conda environment for this repo (Python 3.8.13 recommended version)

   conda create --name shadowsense python=3.8.13
   

3. Install PyTorch from here.

4. Install other required packages with pip

   pip install requirements.txt
   

RT-Trees Dataset

Download

The dataset can be download from this Google Drive link. Training, validation, and testing images for the Individual Tree Crown Detection task with RGB-thermal multi-modal drone imagery are provided. This dataset is primarily meant for self-supervised training, with ground truth annotations available for only the validation and testing sets - bounding boxes for tree crowns with difficult boxes marked as such in the xml file.

14 drone flights with a DJI H20T sensor were conducted from July to November 2022. In each, ~800 image pairs (RGB & thermal) were captured in total, and the images were geographically divided into 75:5:20 train:val:test sets using GPS. The original image pairs have been cropped to 2000x2000 px. Overlap was retained in training images but removed in the evaluation sets, hence the apparent size disparity. More information regarding RT-Trees can be found in the supplementary material of the paper.

Note:

1. Four zip files are provided, one for each of train/validation/test, and the fourth for a labellled subset of the training images, useful for comparison with supervised fine-tuning experiments.

2. Each split of the dataset also contains pre-computed masks for every RGB-thermal pair, obtained using watershed segmentation & morpohological operations as described in the paper and implemented in threshold.py.

Organization

The training script for the proposed self-supervised approach expects the data to be formatted in the following way

ShadowSense
|––– data
   |––– train
      +––– rgb
      +––– thermal
      +––– masks
   |––– test
      +––– rgb
      +––– thermal
      +––– masks
      +––– gt_annotations
   |––– val
      +––– rgb
      +––– thermal
      +––– masks
      +––– gt_annotations

Training

The training flow is programmed in train.py. Begin training with the following command.

python train.py

The evaluation metrics used are implemented in this great repo: Open-Source Visual Interface for Object Detection Metrics.

Citation

If you found this work useful for your own research, please consider citing the paper.

@InProceedings{Kapil_2024_WACV,
    author    = {Kapil, Rudraksh and Marvasti-Zadeh, Seyed Mojtaba and Erbilgin, Nadir and Ray, Nilanjan},
    title     = {ShadowSense: Unsupervised Domain Adaptation and Feature Fusion for Shadow-Agnostic Tree Crown Detection From RGB-Thermal Drone Imagery},
    booktitle = {Proceedings of the IEEE/CVF Winter Conference on Applications of Computer Vision (WACV)},
    month     = {January},
    year      = {2024},
    pages     = {8266-8276}
}