CamOdoCal

Introduction

This C++ library supports the following tasks:

1. Intrinsic calibration of a generic camera.
2. Extrinsic self-calibration of a multi-camera rig for which odometry data is provided.
3. Extrinsic infrastructure-based calibration of a multi-camera rig for which a map generated from task 2 is provided.

The intrinsic calibration process computes the parameters for one of the following three camera models:

• Pinhole camera model
• Unified projection model (C. Mei, and P. Rives, Single View Point Omnidirectional Camera Calibration from Planar Grids, ICRA 2007)
• Equidistant fish-eye model (J. Kannala, and S. Brandt, A Generic Camera Model and Calibration Method for Conventional, Wide-Angle, and Fish-Eye Lenses, PAMI 2006)

By default, the unified projection model is used since this model approximates a wide range of cameras from normal cameras to catadioptric cameras. Note that in our equidistant fish-eye model, we use 8 parameters: k2, k3, k4, k5, mu, mv, u0, v0. k1 is set to 1.

Typically for a set of 4 cameras with 500 frames each, the extrinsic self-calibration takes 2 hours. In contrast, the extrinsic infrastructure-based calibration runs in near real-time, and is strongly recommended if you are calibrating multiple rigs in the same area.

The landing page of the library is located at http://people.inf.ethz.ch/hengli/camodocal/

The workings of the library are described in the three papers:

    Lionel Heng, Bo Li, and Marc Pollefeys,
    CamOdoCal: Automatic Intrinsic and Extrinsic Calibration of a Rig with Multiple Generic Cameras and Odometry,
    In Proc. IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2013.

    Lionel Heng, Mathias Bürki, Gim Hee Lee, Paul Furgale, Roland Siegwart, and Marc Pollefeys,
    Infrastructure-Based Calibration of a Multi-Camera Rig,
    In Proc. IEEE International Conference on Robotics and Automation (ICRA), 2014.
    
    Lionel Heng, Paul Furgale, and Marc Pollefeys,
    Leveraging Image-based Localization for Infrastructure-based Calibration of a Multi-camera Rig,
    Journal of Field Robotics (JFR), 2015.

If you use this library in an academic publication, please cite at least one of the following papers depending on what you use the library for.

Acknowledgements

The primary author, Lionel Heng, is funded by the DSO Postgraduate Scholarship. This work is supported in part by the European Community's Seventh Framework Programme (FP7/2007-2013) under grant #269916 (V-Charge).

The CamOdoCal library includes third-party code from the following sources:

    1. M. Rufli, D. Scaramuzza, and R. Siegwart,
       Automatic Detection of Checkerboards on Blurred and Distorted Images,
       In Proc. IEEE/RSJ International Conference on Intelligent Robots and Systems, 2008.

    2. Sameer Agarwal, Keir Mierle, and Others,
       Ceres Solver.
       https://code.google.com/p/ceres-solver/
    
    3. D. Galvez-Lopez, and J. Tardos,
       Bags of Binary Words for Fast Place Recognition in Image Sequences,
       IEEE Transactions on Robotics, 28(5):1188-1197, October 2012.

    4. L. Kneip, D. Scaramuzza, and R. Siegwart,
       A Novel Parametrization of the Perspective-Three-Point Problem for a
       Direct Computation of Absolute Camera Position and Orientation,
       In Proc. IEEE Conference on Computer Vision and Pattern Recognition, 2011.

    5. pugixml
       http://pugixml.org/

Parts of the CamOdoCal library are based on the following papers:

• Robust pose graph optimization

    G.H. Lee, F. Fraundorfer, and Marc Pollefeys,
    Robust Pose-Graph Loop-Closures with Expectation-Maximization,
    In Proc. IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2013.
  

Build Instructions for Ubuntu

Required dependencies

• BLAS (Ubuntu package: libblas-dev)
• Boost >= 1.4.0 (Ubuntu package: libboost-all-dev)
• CUDA >= 4.2
• Eigen3 (Ubuntu package: libeigen3-dev)
• glog
• OpenCV >= 2.4.6
• SuiteSparse >= 4.2.1

Optional dependencies

• GTest
• OpenMP

1. Before you compile the repository code, you need to install the required dependencies, and install the optional dependencies if required. Download the SuiteSparse libraries from this [link] 1 and do not use the Ubuntu package since the SuiteSparseQR library is missing in the Ubuntu package and is required for covariance evaluation.

2. Build the code.

    mkdir build
    cd build
    cmake -DCMAKE_BUILD_TYPE=Release ..
   

3. If you wish to generate Eclipse project files, run:

    cmake -DCMAKE_BUILD_TYPE=Release -G"Eclipse CDT4 - Unix Makefiles" ..
   

Examples

Go to the build folder where the executables corresponding to the examples are located in. To see all allowed options for each executable, use the --help option which shows a description of all available options.

1. Intrinsic calibration ([src/examples/intrinsic_calib.cc] 2)

    bin/intrinsic_calib -i ../data/images/ -p img --camera-model mei
   

   The camera-model parameter takes one of the following three values: pinhole, mei, and kannala-brandt.

2. Stereo calibration ([src/examples/stereo_calib.cc] 3)

    bin/stereo_calib -i ../data/images/ --prefix-l left --prefix-r right --camera-model mei
   

   The camera-model parameter takes one of the following three values: pinhole, mei, and kannala-brandt.

3. Extrinsic calibration ([src/examples/extrinsic_calib.cc] 4)

   Note 1: Extrinsic calibration requires the use of a vocabulary tree. The vocabulary data corresponding to 64-bit SURF descriptors can be found in data/vocabulary/surf64.yml.gz. This file has to be located in the directory from which you run the executable.

   Note 2: If you wish to use the chessboard data in the final bundle adjustment step to ensure that lines are straight in rectified pinhole images, please copy all [camera_name]_chessboard_data.dat files generated by the intrinsic calibration to the working data folder. The extrinsic calibration will locate these files, and if these files are present, use the chessboard data stored in these files in the final bundle adjustment.

4. Infrastructure-based calibration

   Please visit InfrasCal for more details.