Incremental vs Batch FixedLagSmoother

[Joel Truher]

Hi everybody,

I'm making progress on using GTSAM in Java for the FRC 2d localization problem.

I've been using the BatchFixedLagSmoother, using factors for odometry, vision, and gyro, and it works fine in simulation.

This morning I tried swapping in the IncrementalFixedLagSmoother, because I imagined it would be a faster, drop-in replacement.  It did not work well at all.  It produces incorrect, uncertain estimates for awhile, and then aborts with IndeterminantLinearSystemException.  I can make it "work" by supplying the ground-truth pose as the initial value.

Does anyone have advice about the use of these two smoothers?  Is the incremental one supposed to be so sensitive to initial values?  Are there other limitations or best-practices I should be aware of?  Should I just use the batch one?

Thanks!

Joel