1. 结束构图，停止接收新数据
ros2 service call /finish_trajectory cartographer_ros_msgs/srv/FinishTrajectory "{trajectory_id: 0}"
其中服务类型可以tab出来，服务的格式可以使用如下命令查看
ros2 interface show cartographer_ros_msgs/srv/FinishTrajectory.srv
2. 序列化保存其当前状态
ros2 service call /write_state cartographer_ros_msgs/srv/WriteState "{filename: '/home/develop/bags/mymap.pbstream'}"
3. 将pbstream转换为pgm和yaml
在cartographer_pbstream_to_ros_map文件目录下执行：
./cartographer_pbstream_to_ros_map -map_filestem=${HOME}/bags/mymap -pbstream_filename=${HOME}/bags/mymap.pbstream -resolution=0.05
这样地图已经保存成功了。