Abstract:Graph optimization-based SLAM is the main method under large-scale environment. The framework of this method is composed of two parts, front-end and back-end. Be a continuation paper of our previous one, the four main back-end optimization approaches, which include least square, stochastic gradient descent, relaxation, manifold optimization, and the correspondent literatures are introduced, and two map evaluation methods are presented, that is χ2 error based and MSE error based. The trends of graph optimization-based SLAM method are predicted.