Fail to track local map!

[dapao-0808]

Hi! When I use my own device in IMU+Stereo mode, I always encounter the message 'Fail to track local map!' after running for a period of time! Then reset the map, but this phenomenon does not occur in stereo mode. What are the reasons for this phenomenon?

[boardd]

I am having the same issue! Did you solve it?

[dapao-0808]

My reason is due to excessive calibration errors between the camera and IMU

[boardd]

how did you make sure to calibrate it well?

[dapao-0808]

Kalibr tool can be used for calibration to ensure that the reprojection error is within 0.5 pixels, preferably between 0.1 and 0.2.

[boardd]

hmm I used kalibr, that doesn't seem to be my issue. Do you know how we should synchronize the camera images and imu timestamps? I am guessing they are not synchronized properly maybe.

[dapao-0808]

There are many factors that affect multi-sensor performance: 1. Whether the clock sources of the sensors are consistent; 2. The frequency of IMU should be at least twice as high as that of the camera, of course, the higher the better; 3. Some scenarios may have a significant impact on IMU, and it may be necessary to continue increasing the frequency of IMU or expanding its random walks and noise, etc. If you don't want to consider so much, you can try using a camera like D435i, which will save a lot of trouble