Awesome
ikd-Tree
ikd-Tree is an incremental k-d tree designed for robotic applications. The ikd-Tree incrementally updates a k-d tree with new coming points only, leading to much lower computation time than existing static k-d trees. Besides point-wise operations, the ikd-Tree supports several features such as box-wise operations and down-sampling that are practically useful in robotic applications.
What does ikd-Tree support?
-
Build a balanced k-d tree -
Build()
-
Dynamically insert points to or delete points from the k-d tree -
Add_Points() / Delete_Points()
-
Delete points inside given axis-aligned bounding boxes -
Delete_Point_Boxes()
-
K Nearest Neighbor Search with range limitation -
Nearest_Search()
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Acquire points inside a given axis-aligned bounding box on the k-d tree -
Box_Search()
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Acquire points inside a ball with given radius on the k-d tree -
Radius_Search()
User Manual
- Browse the User Manual for using our ikd-Tree.
Developers
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Yixi CAI 蔡逸熙: Data structure design and implementation
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Wei XU 徐威: Incorporation into LiDAR-inertial odometry package FAST_LIO2 (TRO, 2022)
Related paper
If you are using any code of this repo in your research, please cite at least one of the articles as following:
- ikd-Tree
@article{cai2021ikd,
title={ikd-Tree: An Incremental KD Tree for Robotic Applications},
author={Cai, Yixi and Xu, Wei and Zhang, Fu},
journal={arXiv preprint arXiv:2102.10808},
year={2021}
}
- FAST-LIO2
@article{xu2022fast,
title={Fast-lio2: Fast direct lidar-inertial odometry},
author={Xu, Wei and Cai, Yixi and He, Dongjiao and Lin, Jiarong and Zhang, Fu},
journal={IEEE Transactions on Robotics},
year={2022},
publisher={IEEE}
}
Build & Run demo
1. How to build this project
cd ~/catkin_ws/src
git clone git@github.com:hku-mars/ikd-Tree.git
cd ikd-Tree/build
cmake ..
make -j 9
2. Run our examples
Note: To run Example 2 & 3, please download the PCD file (HKU_demo_pointcloud) into${Your own directory}/ikd-Tree/materials
cd ${Your own directory}/ikd-Tree/build
# Example 1. Check the speed of ikd-Tree
./ikd_tree_demo
# Example 2. Searching-points-by-box examples
./ikd_Tree_Search_demo
# Example 3. An aysnc. exmaple for readers' better understanding of the principle of ikd-Tree
./ikd_tree_async_demo
Example 2: ikd_tree_Search_demo
Box Search Result | Radius Search Result |
---|---|
Points returned from the two search methods are shown in red.
Example 3: ikd_tree_Async_demo
Original Map:
<img src="materials/imgs/HKU_campus.png" style="zoom:50%;" />Box Delete Results:
Points removed from ikd-Tree(red) | Map after box delete |
---|---|
This example is to demonstrate the asynchronous phenomenon in ikd-Tree. The points are deleted by attaching 'deleted' on the tree nodes (map shown in the ) instead of being removed from the ikd-Tree immediately. They are removed from the tree when rebuilding process is performed. Please refer to our paper for more details about delete and rebuilding.
Acknowledgments
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Thanks Marcus Davi for helps in templating the ikd-Tree for more general applications.
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Thanks Hyungtae Lim 임형태 for providing application examples on point clouds.
License
The source code of ikd-Tree is released under GPLv2 license. For commercial use, please contact Mr. Yixi CAI (yixicai@connect.hku.hk) or Dr. Fu ZHANG (fuzhang@hku.hk).