How to align GNSS with locally created LiDAR maps (DLIO / RTAB-Map) in Autoware?

[adityac-ymsli]

Hello Team,

I am working on Autoware localization using a LiDAR map that was created using third-party SLAM packages:

• DLIO (Odometry extraction from lidar and imu)
• RTAB-Map (Map creation from odom and lidar)

The LiDAR sensors used for mapping are (Either is available):

• Livox Mid 360
• Ouster OS1

The map generated by these tools is in a local Cartesian coordinate frame (starting at 0,0,0).
I am also using a GPS sensor that provides global position (latitude, longitude, altitude).

My confusion is:
Since GNSS provides pose in a global coordinate system and the LiDAR map is locally created, how does Autoware align the GPS pose with the LiDAR map?

Additionally:

1. Does Autoware require the LiDAR map to be georeferenced (e.g., UTM or MGRS)?
2. If the map is purely local (no global reference), how should the earth → map transform be defined?
3. Is there a recommended workflow for aligning SLAM-generated maps (DLIO / RTAB-Map) with GPS data?
4. Should GPS be used only for initial pose, or can it continuously correct drift in such a setup?

I would appreciate clarification on the proper coordinate transformation pipeline when combining GNSS with third-party SLAM-generated maps or if there is any other internal method supported for the same.

Thank you.