how to deal with the ill-conditioned Hession matrix

[lfy-gogogo]

Thank you for sharing! I read your code, and I saw that you use GN or DL to solve the optimization problem. As I know, GN and DL method are not stable, we use LM in a general way. What extra work do you make to solve this problem to use GN or DL happily?

[liuhaomin]

Generally camera blocks are invertible, only some points without sufficient parallax have ill-conditioned Hessian. If the information garthered on a inverse depth is too small (less than the threshold epsdST), it will be treated as a fixed point and not be marginalized during Schur complement construction.

ICE-BA/Backend/BundleAdjustment/GlobalBundleAdjustorGN.cpp

Line 765 in b004bb5

} else if (KF.m_Axs[ix].m_Sadx.m_add.m_a > epsd) {