Including heading/yaw of dual antenna GPS

[lio94]

Currently I build a map for a while before getting GPS signal. When I get GPS signal, the map/cloud position is updated, but orientation stays the same than where the odom frame was originally initialized when no GPS was available. (I do not have 9DOF IMU, only 6DOF)

Do you have any suggestions how I could include the accurate heading information I have, so that when GPS information is received, the map would also become aligned relative to true north?

My end goal would be to have a georeferenced map of the environment, relative to a local cartesian frame.

[JokerJohn]

@lio94 First, you need to address the issue with the 6-axis IMU. Please refer to: LIO_SAM_6AXIS. Next, if you want to use a 6-DOF GPS constraint, you simply need to replace the GPS Factor with a Pose3 type Prior Factor in mapOptimization.cpp and assign it a relatively strong weight (noise model).