IMU factors upgrade & request for feedback

[Dellaert, Frank]

All

if you’re using GTSAM’s IMU factors, you might want to please pull the latest develop and/or pip install gtsam-develop again: all IMU factors have gotten better, by switching to the slightly more expensive but better-behaved SE_2(3) Logmap error. In addition, you could opt to

• use the new GalileanFactor, which handsomely outperforms the older IMU factors.
• Set GTSAM_NAVSTATE_EXPMAP to ON. This also changes the factor graph optimization to use SE_2(3) Expmap; mileage may vary, but worth checking out for possible faster convergence.

More information and reports in https://github.com/borglab/gtsam/pull/2774

If you are experimenting with this, please let me us know (in reply) what your findings are. And please post issues on the GTSAM repo if you find problems. I would like to release GTSAM 4.3 as soon as possible and this is one of the key changes that landed in the past few weeks. 

One of the of the other things that landed was better behavior of pose graph optimization and the FAST-Sync initializer, and our GPU support. Also interested in your findings with those!

Happy Optimizing!

Frank