fpsample

fpsample

Python efficient farthest point sampling (FPS) library, 100x faster than numpy implementation.

fpsample is coupled with numpy and built upon Rust pyo3 bindings. This library aims at achieving the best performance for FPS in single-threaded CPU environment.

🎉 PyTorch version with native multithreading, batch ops, Autograd and CUDA supports is in pytorch_fpsample. 🎉

Installation

Install from PyPI

numpy>=1.16.0 is required. Install fpsample using pip:

pip install -U fpsample

NOTE: Only 64 bit package provided.

If you encounter any installation errors, please make an issue and try to compile from source.

Build from source

The library is built using maturin. Therefore, rust and cargo are required for compiling.

pip install -r requirements.txt

C++ compiler must support C++14. For example, gcc>=8 or clang>=5.

Build the library and install using:

maturin develop --release

Compile options

For macos users, if the compilation fails to link libstdc++, try to pass FORCE_CXXSTDLIB=c++ as an environment variable.

For users that want larger maximum dimension support (currently set to 8), modify build_info.rs and compile.

Direct porting of QuickFPS

See src/bucket_fps/c_warpper.cpp and src/bucket_fps/_ext/ for details.

Usage

import fpsample
import numpy as np

# Generate random point cloud
pc = np.random.rand(4096, 3)
## sample 1024 points

# Vanilla FPS
fps_samples_idx = fpsample.fps_sampling(pc, 1024)

# FPS + NPDU
fps_npdu_samples_idx = fpsample.fps_npdu_sampling(pc, 1024)
## or specify the windows size
fps_npdu_samples_idx = fpsample.fps_npdu_sampling(pc, 1024, k=64)

# FPS + NPDU + KDTree
fps_npdu_kdtree_samples_idx = fpsample.fps_npdu_kdtree_sampling(pc, 1024)
## or specify the windows size
fps_npdu_kdtree_samples_idx = fpsample.fps_npdu_kdtree_sampling(pc, 1024, k=64)

# KDTree-based FPS
kdtree_fps_samples_idx = fpsample.bucket_fps_kdtree_sampling(pc, 1024)

# Bucket-based FPS or QuickFPS
kdline_fps_samples_idx = fpsample.bucket_fps_kdline_sampling(pc, 1024, h=3)

• FPS: Vanilla farthest point sampling. Implemented in Rust. Achieve the same performance as numpy.
• FPS + NPDU: Farthest point sampling with nearest-point-distance-updating (NPDU) heuristic strategy. 5x~10x faster than vanilla FPS. Require dimensional locality and give sub-optimal answers.
• FPS + NPDU + KDTree: Farthest point sampling with NPDU heuristic strategy and KDTree. 3x~8x faster than vanilla FPS. Slightly slower than FPS + NPDU. But DOES NOT require dimensional locality.
• KDTree-based FPS: A farthest point sampling algorithm based on KDTree. About 40~50x faster than vanilla FPS.
• Bucket-based FPS or QuickFPS: A bucket-based farthest point sampling algorithm. About 80~100x faster than vanilla FPS. Require an additional hyperparameter for the height of the KDTree. In practice, h=3 or h=5 is recommended for small data, h=7 is recommended for medium data, and h=9 for extremely large data.

NOTE: In most cases, Bucket-based FPS is the best choice, with proper hyperparameter setting.

Determinism

For deterministic results, fix the first sampled point index by passing the start_idx parameter.

kdline_fps_samples_idx = fpsample.bucket_fps_kdline_sampling(pc, 1024, h=3, start_idx=0)

OR set the random seed before calling the function.

np.random.seed(42)

Performance

Setup:

• CPU: Intel(R) Core(TM) i9-10940X CPU @ 3.30GHz
• RAM: 128 GiB
• SYSTEM: Ubuntu 22.04.3 LTS

Run benchmark:

pytest bench/ --benchmark-columns=mean,stddev --benchmark-sort=mean

Results:

---------------- benchmark '1024 of 4096': 7 tests -----------------
Name (time in ms)                   Mean            StdDev
--------------------------------------------------------------------
test_bucket_fps_kdline_4k_h5      1.9469 (1.0)      0.0354 (1.54)
test_bucket_fps_kdline_4k_h3      2.0028 (1.03)     0.0750 (3.27)
test_fps_npdu_4k                  3.3361 (1.71)     0.0229 (1.0)
test_bucket_fps_kdline_4k_h7      3.6899 (1.90)     0.0548 (2.39)
test_bucket_fps_kdtree_4k         6.5072 (3.34)     0.4018 (17.52)
test_fps_npdu_kdtree_4k          12.3689 (6.35)     0.0380 (1.66)
test_vanilla_fps_4k              14.1073 (7.25)     0.4171 (18.20)
--------------------------------------------------------------------

----------------- benchmark '4096 of 50000': 7 tests -----------------
Name (time in ms)                     Mean            StdDev
----------------------------------------------------------------------
test_bucket_fps_kdline_50k_h7      25.7244 (1.0)      0.5605 (1.0)
test_bucket_fps_kdline_50k_h5      30.0820 (1.17)     0.5973 (1.07)
test_bucket_fps_kdline_50k_h3      59.9939 (2.33)     1.0208 (1.82)
test_bucket_fps_kdtree_50k         98.2151 (3.82)     5.1610 (9.21)
test_fps_npdu_50k                 129.3240 (5.03)     0.5638 (1.01)
test_fps_npdu_kdtree_50k          287.4457 (11.17)    8.5040 (15.17)
test_vanilla_fps_50k              794.4958 (30.88)    5.2105 (9.30)
----------------------------------------------------------------------

------------------- benchmark '50000 of 100000': 7 tests -------------------
Name (time in ms)                         Mean              StdDev
----------------------------------------------------------------------------
test_bucket_fps_kdline_100k_h7        247.6833 (1.0)        4.8640 (6.85)
test_bucket_fps_kdline_100k_h5        393.8612 (1.59)       3.8099 (5.37)
test_bucket_fps_kdtree_100k           419.4466 (1.69)       8.5836 (12.09)
test_bucket_fps_kdline_100k_h9        437.0670 (1.76)       2.8537 (4.02)
test_fps_npdu_100k                  2,990.6574 (12.07)      0.7101 (1.0)
test_fps_npdu_kdtree_100k           4,236.8786 (17.11)      3.3208 (4.68)
test_vanilla_fps_100k              20,131.7747 (81.28)    155.4407 (218.91)
----------------------------------------------------------------------------

Reference

The nearest-point-distance-updating (NPDU) heuristic strategy is proposed in the following paper:

@INPROCEEDINGS{9919246,
  author={Li, Jingtao and Zhou, Jian and Xiong, Yan and Chen, Xing and Chakrabarti, Chaitali},
  booktitle={2022 IEEE Workshop on Signal Processing Systems (SiPS)},
  title={An Adjustable Farthest Point Sampling Method for Approximately-sorted Point Cloud Data},
  year={2022},
  volume={},
  number={},
  pages={1-6},
  doi={10.1109/SiPS55645.2022.9919246}
}

Bucket-based farthest point sampling (QuickFPS) is proposed in the following paper. The implementation is based on the author's Repo. To port the implementation to other C++ program, check this for details.

@article{han2023quickfps,
  title={QuickFPS: Architecture and Algorithm Co-Design for Farthest Point Sampling in Large-Scale Point Clouds},
  author={Han, Meng and Wang, Liang and Xiao, Limin and Zhang, Hao and Zhang, Chenhao and Xu, Xiangrong and Zhu, Jianfeng},
  journal={IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems},
  year={2023},
  publisher={IEEE}
}

Thanks to the authors for their great work.