Ah, that makes more sense, all I had previously looked at was the motion_model-design.md.
The state that you linked looks great for tracked objects!
For ego localization, I suggested a 3DOF orientation for a couple reasons:
- We found pitch was useful in speed controls to determine if the car was on a hill or not.
- I am unfamiliar with the current ndt_matching, but most lidar localization implementations work better when you have roll and pitch, since small roll or pitch angles can drastically change the lidar scan which is used for matching. I think ndt_matching estimates Pose with full orientation anyway.
- Novatel SPAN devices (or most GPS-INS systems) provide a full 3DOF orientation, so we might as well use it.
One other difference I noticed is the autoware.auto tracker EKF does not estimate Z position. This is probably fine, the z value could just be passed through from detection. However, for ego localization, the Z position is definitely needed.