How to align map with ground truth position obtained from Gazebo?

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Hi does someone mind please explaining how to figure out where the robot is in a map without using amcl or any localization, and only using ground truth position published by Gazebo? Or is this not possible?

I know I can get perfect odom->baselink transformation, and have amcl publish map->odom transformation, but that still does not perfectly localize the robot.

Thank you for your help in advance!