Confused by Ceres Jacobian Explanation about manif HOT 2 CLOSED

Hi @willat343,

Sorry for the ceres-related doc page, it isn't great, the notation isn't methodical and it should be revamped.

The tldr is that manif analytic jacobians aren't compatible with ceres.

Altho I'm not familiar with ceres 2.+, a quick look seems to indicate that nothing change from 1.x in the sense that ceres expects Jacobians to be expressed with respect to the underlying representation vector (AmbientSize) while manif express them w.r.t a perturbation on the tangent space (TangentSize).
If I re-use the notation from the ceres-related doc page,

J_w^e = J_{x+w}^e x J_w^{x+w}
(ResidualSize,TangentSize) = (ResidualSize,AmbientSize) x (AmbientSize,TangentSize)

This notation is bad as it suggests that all Jacobians are w.r.t the tangent space which is not the case as you can see from the matrix dimensions.

This being said, manif supports ceres autodiff. If you're looking for analytic Jacobians to be used with ceres, you could consider using Sophus.

You may be interested in having a look at the following issues for further reading: ceres-solver/ceres-solver#387 & ceres-solver/ceres-solver#615.

from manif.

Thank you for your explanation @artivis, and for those links, that actually does help a bit. Happy to close this for now.

from manif.