There are actually even more. You can actually have 12 different variations depending on certain choices. Though the other sources of differences are minor.
This is actually a great source of frustration in the robotics state estimation community, as you have the influential University of Minnesota using JPL, and most other universities using Hamiltonian.
> But turns out, a hierarchical structure can NOT correctly represent some movement patterns in the real world, like branches on a tree moving or overhead cables.
Could you expand a bit on this? Do you mean that it might miss small fast moving objects due to losing fidelity at the coarse resolutions. Or is there actually some sort of movement that the hierarchical structure can't interpret.
https://arxiv.org/abs/1711.02508
This is actually a great source of frustration in the robotics state estimation community, as you have the influential University of Minnesota using JPL, and most other universities using Hamiltonian.