CAO Shaozu

Hi @dean1314. It seems that the std of Doppler shift is not provided by Novatel. You may infer one from the ADR (Accumulated Doppler Range) value.

Hi, @GSORF. Thanks for your efforts on this issue. I will leave this issue open in case someone has the same problem. I just want to add that another solution...

Hi, @amirmoeini. From section IV.B.(3) of [vins-mono paper](https://ieeexplore.ieee.org/document/8421746), you may find that the first three residuals are also related to Ba and Bg.

When calculate \hat{\alpha}, \hat{\beta} and \hat{\gamma} in equation 27, Ba and Bg are used. Notice that those states may change during optimization, we must apply corrections to \hat{\alpha}, \hat{\beta} and...

> Please note that the numerical values of \hat{\alpha}, \hat{\beta} and \hat{\gamma} are used in the first three rows, and there fore they do not affect the optimization problem in...

Hi, actually velocity has been initialized in the initialization phase, and the pre-integration term (i.e. alpha in the paper) is not the position.

Hi, the initialization will work fine even the initial speed is not 0. The variable `delta_v` in pre-integration is not exactly the velocity, instead it's a pre-integration constraint shown in...

I think the IMU excitation during the initialization may not enough. Actually such near-planar motion is really a challenging case for VINS-Mono.

You can try with [VINS-Fusion](https://github.com/HKUST-Aerial-Robotics/VINS-Fusion).

Seems you are using fisheye camera but did not provide any mask image for that.