This repository contains the code of our paper "Informative Path Planning for Active Learning in Aerial Semantic Mapping". We propose a new approach for using unmanned aerial vehicles (UAVs) to autonomously collect useful data for active learning. The paper can be found here.
Semantic segmentation of aerial imagery is an important tool for mapping and earth observation. However, supervised deep learning models for segmentation rely on large amounts of high-quality labelled data, which is labour-intensive and time-consuming to generate. To address this, we propose a new approach for using unmanned aerial vehicles (UAVs) to autonomously collect useful data for model training. We exploit a Bayesian approach to estimate model uncertainty in semantic segmentation. During a mission, the semantic predictions and model uncertainty are used as input for terrain mapping. A key aspect of our pipeline is to link the mapped model uncertainty to a robotic planning objective based on active learning. This enables us to adaptively guide a UAV to gather the most informative terrain images to be labelled by a human for model training. Our experimental evaluation on real-world data shows the benefit of using our informative planning approach in comparison to static coverage paths in terms of maximising model performance and reducing labelling efforts.
If you found this work useful for your own research, feel free to cite it.
@inproceedings{ruckin2022informative,
title={Informative Path Planning for Active Learning in Aerial Semantic Mapping},
author={R{\"u}ckin, Julius and Jin, Liren and Magistri, Federico and Stachniss, Cyrill and Popovi{\'c}, Marija},
booktitle={2022 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)},
year={2022},
organization={IEEE}
}
Our planning strategy for active learning in UAV-based terrain mapping. During a mission, we estimate model uncertainty in semantic segmentation (top-right) and fuse it in a global terrain map (bottom-right). Based on the map, our approach guides a UAV to collect most useful (most uncertain) training images for labelling (left). Orange arrows indicate candidate paths and red shows the chosen path. In this way, our pipeline reduces the number of images that must be labelled by a human.
Overview of our proposed approach. We start with a pretrained network for probabilistic semantic segmentation, deployed on a UAV. During a mission, the network processes RGB images to predict pixel-wise semantic labels and model uncertainties, which are projected onto the ground to build global maps capturing these variables. Based on the estimated model uncertainty, the current UAV position, and the current map state, our algorithm plans paths for the UAV to collect the most uncertain (most informative) training data for improving the network performance. After the mission, the collected images are labelled by an annotator and used for network retraining. By guiding the UAV to collect informative training data, our pipeline reduces the labelling effort.
- Clone repo and initialize submodules:
git clone git@github.com:dmar-bonn/ipp-al.git
cd ipp-al
git submodule update --init
pip3 install -r requirements.txt
- Download and unpack the Potsdam orthomosaic here.
- Create a train-validation-test image split as described in the paper.
- Pretrain a Bayesian-ERFNet model on cityscapes and save the checkpoint erfnet_cityscapes.ckpt.
- Empty the training_set/images and training_set/anno folder of the Potsdam dataset folder.
- Adapt the path_to_orthomosaic and path_to_anno attributes in your config/config.yaml file to the potsdam_orthomosaic.zip RGB and Labels absolute directory paths respectively.
- Adapt the path_to_dataset in your bayesian_erfnet/agri_semantics/config/potsdam.yaml file to the absolute Potsdam dataset directory path.
- Adapt the path_to_checkpoint in your config/config.yaml to the absolute erfnet_cityscapes.ckpt path.
- To run the active learning pipeline, set the proper python path:
export PYTHONPATH=$(pwd):$(pwd)/bayesian_erfnet/
python3 main.py
The active learning pipeline executes the number of missions specified in config/config.yaml. All config files are saved to the disk. During a mission, the collected train data is saved to the disk. After each mission, the map, the planned path, and the evaluation metrics of the retrained model are saved to the disk.
In general, we follow the Python PEP 8 style guidelines. Please install black to format your python code properly. To run the black code formatter, use the following command:
black -l 120 path/to/python/module/or/package/
To optimize and clean up your imports, feel free to have a look at this solution for PyCharm.
Julius Rückin, jrueckin@uni-bonn.de, Ph.D. student at PhenoRob - University of Bonn
We would like to thank Matteo Sodano and Tiziano Guadagnino for help with our experiments and proofreading. We would like to thank Jan Weyler for providing a PyTorch Lightning implementation of ERFNet.
This work was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy - EXC 2070 – 390732324. Authors are with the Cluster of Excellence PhenoRob, Institute of Geodesy and Geoinformation, University of Bonn.