跟做高博的《一起做RGB-D SLAM》系列时，出现了挺多bug的（主要因为自己还是个小白），在此记录下解决过程。（ubuntu18.04，opencv3.4.9）

一起做RGB-D SLAM（6）：

1.Ubuntu18安装g2o

在ubuntu18.04下安装g2o还是挺容易的，先安装依赖：

sudo apt-get install qtcreator libeigen3-dev libsuitesparse-dev qtdeclarative5-dev qt5-qmake libqglviewer-dev-qt5

最后一个依赖也可以改为libqglviewer-dev-qt4，分别是基于QT5和4开发的，选择一个需要的就好。这个依赖关乎到g2o的viewer的安装，如果安不上的话，对照官方文档安装libqglviewer（下载解压后用QTcreator打开libQGLViewer-2.7.2/QGLViewer/QGLViewer.pro，构建全部）。

安好依赖后下载g2o安装包：github，然后cd到g2o的根目录下：

mkdir build
cd build
cmake ..
make
sudo make install

2.error: no matching function for call to ‘g2o::BlockSolver<g2o::BlockSolverTraits<6, 3> >::BlockSolver(SlamLinearSolver*&)’ SlamBlockSolver* blockSolver = new SlamBlockSolver( linearSolver );

这个错误是因为g2o新版本和旧版本在智能指针上不兼容导致的。参照关于关于高博3d2d程序报错的改动，把src/slamEnd.cpp（下图白框处内容）改为：

unique_ptr<SlamBlockSolver::LinearSolverType> linearSolver (new SlamLinearSolver());
unique_ptr<SlamBlockSolver> blockSolver (new SlamBlockSolver(move(linearSolver)));
g2o::OptimizationAlgorithmLevenberg* solver = new g2o::OptimizationAlgorithmLevenberg(move(blockSolver));

3.CMake Error: The current CMakeCache.txt directory /home/max/slam0.1/slam/build/CMakeCache.txt is different than the directory /home/max/slam0.1/slamt/build where CMakeCache.txt was created. This may result in binaries being created in the wrong place. If you are not sure, reedit the CMakeCache.txt

把build文件下的内容都删掉再重新cmake …就行。

4.error: ‘struct FRAME’ has no member named ‘frameID’ f.frameID = index;

在include/slamBase.h里（下图白框处）加上：

int frameID;

5.CMakeFiles/slamEnd.dir/slamEnd.cpp.o：在函数‘main’中：slamEnd.cpp:(.text+0xbf2)：对‘g2o::OptimizationAlgorithmLevenberg::OptimizationAlgorithmLevenberg(std::unique_ptr<g2o::Solver, std::default_deleteg2o::Solver >)’未定义的引用slamEnd.cpp:(.text+0xc17)：对‘g2o::SparseOptimizer::SparseOptimizer()’未定义的引用 slamEnd.cpp:(.text+0xc30)：对‘g2o::SparseOptimizer::setAlgorithm(g2o::OptimizationAlgorithm*)’未定义的引用slamEnd.cpp:(.text+0xc44)：对‘g2o::SparseOptimizer::setVerbose(bool)’未定义的引用 slamEnd.cpp:(.text+0xc59)：对‘g2o::VertexSE3::VertexSE3()’未定义的引用 slamEnd.cpp:(.text+0xf71)：对‘g2o::VertexSE3::VertexSE3()’未定义的引用 slamEnd.cpp:(.text+0xff3)：对‘g2o::EdgeSE3::EdgeSE3()’未定义的引用 slamEnd.cpp:(.text+0x11d1)：对‘g2o::OptimizableGraph::addEdge(g2o::OptimizableGraph::Edge*)’未定义的引用 slamEnd.cpp:(.text+0x12a6)：对‘g2o::OptimizableGraph::save(char const*, int) const’未定义的引用

src/CMakeLists.txt里添加的slamEnd二进制执行文件要链接一些g2o库，修改为：

ADD_EXECUTABLE( slamEnd slamEnd.cpp )
TARGET_LINK_LIBRARIES( slamEnd
    slambase
    ${ OpenCV_LIBS}
    ${ PCL_LIBRARIES} 
    g2o_core g2o_types_slam3d g2o_solver_csparse g2o_stuff g2o_csparse_extension ${ CSPARSE_LIBRARY})

ps：g2o的引用要写在src下的CMakeLists.txt里。