g2o - General Graph Optimization

g2o is an open-source C++ framework for optimizing graph-based nonlinear error functions. g2o has been designed to be easily extensible to a wide range of problems and a new problem typically can be specified in a few lines of code. The current implementation provides solutions to several variants of SLAM and BA.

A wide range of problems in robotics as well as in computer-vision involve the minimization of a non-linear error function that can be represented as a graph. Typical instances are simultaneous localization and mapping (SLAM) or bundle adjustment (BA). The overall goal in these problems is to find the configuration of parameters or state variables that maximally explain a set of measurements affected by Gaussian noise. g2o is an open-source C++ framework for such nonlinear least squares problems. g2o has been designed to be easily extensible to a wide range of problems and a new problem typically can be specified in a few lines of code. The current implementation provides solutions to several variants of SLAM and BA. g2o offers a performance comparable to implementations of state-of-the-art approaches for the specific problems (02/2011).

Papers Describing the Approach:

Rainer Kuemmerle, Giorgio Grisetti, Hauke Strasdat, Kurt Konolige, and Wolfram Burgard g2o: A General Framework for Graph Optimization IEEE International Conference on Robotics and Automation (ICRA), 2011 http://ais.informatik.uni-freiburg.de/publications/papers/kuemmerle11icra.pdf

License

g2o is licensed under the BSD License. However, some libraries are available under different license terms. See below.

The following parts are licensed under LGPL3+:

• csparse_extension

The following parts are licensed under GPL3+:

• g2o_viewer
• g2o_incremental
• slam2d_g2o (example for 2D SLAM with a QGLviewer GUI)

Please note that some features of CHOLMOD (which may be used by g2o, see libsuitesparse below) are licensed under the GPL. To avoid that your binary has to be licensed under the GPL, you may have to re-compile CHOLMOD without including its GPL features. The CHOLMOD library distributed with, for example, Ubuntu or Debian includes the GPL features. The supernodal factorization is considered by g2o, if it is available.

Within the folder EXTERNAL we include software not written by us to guarantee easy compilation.

• csparse: LPGL2.1 (see EXTERNAL/csparse/License.txt) csparse is compiled if it is not provided by the system.
• ceres: BSD (see EXTERNAL/ceres/LICENSE) Headers to perform Automatic Differentiation
• freeglut: X Consortium (Copyright (c) 1999-2000 Pawel W. Olszta) We use a stripped down version for drawing text in OpenGL.

See the doc folder for the full text of the licenses.

g2o is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the licenses for more details.

Requirements

g2o requires cmake and Eigen3 to build. The other requirements are optional.

• cmake http://www.cmake.org/
• Eigen3 http://eigen.tuxfamily.org
• suitesparse http://www.cise.ufl.edu/research/sparse/SuiteSparse/
• Qt5 http://qt-project.org
• libQGLViewer http://www.libqglviewer.com/

On Ubuntu / Debian these dependencies are resolved by installing the following packages. - cmake - libeigen3-dev - libsuitesparse-dev - Qt4: libqt4-dev, qt4-qmake, libqglviewer-dev (Or libqglviewer-qt4-dev in modern distributions) - Qt5: libqt5-dev, qt5-qmake, libqglviewer-dev

Mac OS X

If using Homebrew, then

brew install homebrew/science/g2o

will install g2o together with its required dependencies. In this case no manual compilation is necessary.

Compilation

Our primary development platform is Linux. Experimental support for Mac OS X, Android and Windows (MinGW or MSVC). We recommend a so-called out of source build which can be achieved by the following command sequence.

• mkdir build
• cd build
• cmake ../
• make

The binaries will be placed in bin and the libraries in lib which are both located in the top-level folder. If you are compiling on Windows, please download Eigen3 and extract it. Within cmake-gui set the variable G2O_EIGEN3_INCLUDE to that directory.

Cross-Compiling for Android

• mkdir build
• cd build
• cmake -DCMAKE_TOOLCHAIN_FILE=../script/android.toolchain.cmake -DANDROID_NDK=<YOUR_PATH_TO_ANDROID_NDK_r10d+> -DCMAKE_BUILD_TYPE=Release -DANDROID_ABI="armeabi-v7a with NEON" -DEIGEN3_INCLUDE_DIR="<YOUR_PATH_TO_EIGEN>" -DEIGEN3_VERSION_OK=ON .. && cmake --build .

Acknowledgments

We thank the following contributors for providing patches:

• Simon J. Julier: patches to achieve compatibility with Mac OS X and others.
• Michael A. Eriksen for submitting patches to compile with MSVC.
• Mark Pupilli for submitting patches to compile with MSVC.

Contact information

Rainer Kuemmerle kuemmerl@informatik.uni-freiburg.de
Giorgio Grisetti grisetti@dis.uniroma1.it
Hauke Strasdat strasdat@gmail.com
Kurt Konolige konolige@willowgarage.com
Wolfram Burgard burgard@informatik.uni-freiburg.de