高翔的g2o_ba_example在ubuntu18环境下报错

关于高翔的g2o_ba_example在ubuntu18环境下报错的问题，我是用的opencv4，g2o版本也比较新，所以源码存在问题，修改方法是

第一部分报错地方修改

// 使用Cholmod中的线性方程求解器

g2o::BlockSolver_6_3::LinearSolverType* linearSolver = new g2o::LinearSolverCholmod<g2o::BlockSolver_6_3::PoseMatrixType> ();

// 6*3 的参数

//g2o::BlockSolver_6_3* block_solver = new g2o::BlockSolver_6_3( linearSolver );

g2o::BlockSolver_6_3* block_solver = new g2o::BlockSolver_6_3( unique_ptr<g2o::BlockSolver_6_3::LinearSolverType>(linearSolver) ); //矩阵块求解器

// L-M 下降

//g2o::OptimizationAlgorithmLevenberg* algorithm = new g2o::OptimizationAlgorithmLevenberg( block_solver );

g2o::OptimizationAlgorithmLevenberg* algorithm = new g2o::OptimizationAlgorithmLevenberg( unique_ptr<g2o::BlockSolver_6_3>(block_solver)); //迭代算法

第二部分报错地方修改

cv::Ptr<cv::FeatureDetector> detector = cv::ORB::create();

cv::Ptr<cv::DescriptorE