HomLib

C++ library for computing homographies with support in MATLAB and Python.

Solvers

This repository contains four solvers for computing homographies with simultaneous radial distortion correction and/or incorporating IMU data.

Authors (year)	Number of points	Minimal	Radial distortion coeff.	IMU data	General homography	Separarate intrinsic/extrinsic
Fitzgibbon (2001)	5		✔️		✔️
Kukelova et al. (2015)	5	✔️	✔️ (2)		✔️
Valtonen Örnhag et al. (2020)	4	✔️		✔️		✔️
Valtonen Örnhag et al. (2021)	3	✔️		✔️		✔️
	4	✔️	✔️	✔️		✔️

The solvers by Valtonen Örnhag et al. are original implementations, the other are re-implementations. If you use the code in your work, please cite the following articles:

@InProceedings {valtonen-ornhag-etal-2020-icpr,
    author    = {Valtonen~{\"O}rnhag, Marcus and Persson, Patrik and Wadenb{\"a}ck, M{\aa}rten and {\AA}str{\"o}m, Kalle and Heyden, Anders},
    title     = {Minimal Solvers for Indoor UAV Positioning},
    booktitle = {Proceedings of the 25th International Conference on Pattern Recognition (ICPR)},
    month     = {January},
    year      = {2021},
    pages     = {1136-1143}
}


@InProceedings{valtonen-ornhag-etal-2021-wacv,
    author    = {Valtonen~{\"O}rnhag, Marcus and Persson, Patrik and Wadenb{\"a}ck, M{\aa}rten and {\AA}str{\"o}m, Kalle and Heyden, Anders},
    title     = {Efficient Real-Time Radial Distortion Correction for UAVs},
    booktitle = {Proceedings of the IEEE/CVF Winter Conference on Applications of Computer Vision (WACV)},
    month     = {January},
    year      = {2021},
    pages     = {1751-1760}
}

Dependencies

The source code depends on Eigen 3 (older versions not compatible). Installation for Ubuntu/Debian:

    $ apt-get install libeigen3-dev

The source code has been compiled and tested on Ubuntu 18.04 (Bionic Beaver) with g++-7 to g++-9 as well as clang++-7 to clang++-9. Furthermore, it is tested on OSX with Xcode 10-12.

Using the solver in MATLAB

It is possible to MEX-compile the solver and use it in MATLAB. Check the compile_mex.m function in the MATLAB directory. You may have to change the path to Eigen, e.g. /usr/local/include/eigen3.

Using the solver in Python

The official python repository is python-homlib. A pre-alpha release is available at PyPi, and can be installed using

    $ pip install homlib

About the solvers

Many of the solvers were generated using the automatic generator proposed by Larsson et al. "Efficient Solvers for Minimal Problems by Syzygy-based Reduction" (CVPR 2017)