How to get Ground truth and use it for comparison ??

[saqihussainkalan]

Hello ,
i am using Ros Noetic,on Ubuntu 20.04 LTS,

i have recorded the ros bag file which include the topics:

/tf, tracked_pose, ,imu, /map, /scan,

Now to generate the ground truth we need to have serialized state of a fully optimized trajectory file (optimized.pbstream) as per this documentation Auto generate ground truth using this command
cartographer_autogenerate_ground_truth -pose_graph_filename optimized.pbstream -output_filename relations.pbstream -min_covered_distance 100 -outlier_threshold_meters 0.15 -outlier_threshold_radians 0.02,

when i searched how to make this file , i found this Exploiting the map generated by Cartographer ROS
but i am not able to use this command to generate the .pbstream , because it needs the horizontal and verticle links connected to base link, where as in my case i use only one lidar which gives me /laser,

if you have any idea where i am going wrong please help