questions about rootba on visual odometry

[empty-spacebar]

Hello, thanks for open-sourcing your great work.

Here are my questions:

1, Why did you implement rootBA on Basalt rather than DSO, another famous work from TUM? Since rootBA is designed for solving large-scale BA, and DSO maintains a much larger BA.

2, Actually I implemented rootBA on a direct visual odometry, BUT it ended up with about 7% more CPU occupation, worse accuracy and robustness. HOWEVER basalt shows remarkable performance no matter on runtime or accuracy. Is it the answer of question 1?

3, Does Basalt's accuracy benefit from stereographic projection rather than rootBA?

4, "...to keep the number of optimiziation variables small, we parametrize the bearing vector in 3D space using a minimal representation, which is two-dimensional", says the paper of Basalt. But actually the optimiziation dimension is still three. Could you please make a further explanation?

[hitdshu]

Well, for question 4, actually, the bearing is parameterized via stereographic projection (which has 2 DOF). But there is a inverse depth for each landmark point. So the final optimization dimension is still three, with 2 being bearing and 1 being inverse depth.

Other problems are much harder to answer(at least for me...), there are so many factors affecting the accuracy. Such as the optical flow accuracy, the keyframe selection strategy, etc...