6.4 实践：g2o

一、g2o的安装

//安装依赖项
sudo apt-get install libqt4-dev qt4-qmake libqglviewer-dev libsuitesparse-dev libcxsparse3.1.4 libcholmod3.0.6
//去git hub下载源码后编译安装
cd g2o
mkdir build
cd build
cmake ..
make
sudo make install

二、P124页程序

注意构建图优化，设定g2o时，g2o版本与原作者不同可能导致报错，原因在于：
Block* solver_ptr = new Block ( linearSolver );
这里的构造函数BloclSolver更改了，下述博客中给出了较为详细的解释：
https://blog.csdn.net/robinhjwy/article/details/78084210
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在第六章的实验中，只需要把初始化部分函数更改为一下代码即可：

typedef g2o::BlockSolver< g2o::BlockSolverTraits<3,1> > Block;  // pose 维度为 6, landmark 维度为 3

//Block::LinearSolverType* linearSolver = new g2o::LinearSolverDense(); // 线性方程求解器
std::unique_ptr linearSolver ( new g2o::LinearSolverDense());

//Block* solver_ptr = new Block ( linearSolver );
//std::unique_ptr solver_ptr ( new Block ( linearSolver));
std::unique_ptr solver_ptr ( new Block ( std::move(linearSolver)));     // 矩阵块求解器

//g2o::OptimizationAlgorithmLevenberg* solver = new g2o::OptimizationAlgorithmLevenberg ( solver_ptr);
g2o::OptimizationAlgorithmLevenberg* solver = new g2o::OptimizationAlgorithmLevenberg ( std::move(solver_ptr));

g2o::SparseOptimizer optimizer;

optimizer.setAlgorithm ( solver );