KITTI files of different length: "data matrices must have the same shape"

[liangsongLee]

Hello, I used orbslam2 to run KITTI in mono mode. And I got the trajectory .txt file of keyframes in the form of TUM. Then I use --save_as_kitti to transform the .txt file to KITTI's form. Finally, I use evo_traj kitti KeyFrameTrajectory.txt --ref=ground_truth.txt -p --plot_mode=xz . I got a plot without align. However, I dont know how to align it. Please help me , thank you very much.

[MichaelGrupp]

See here: https://github.com/MichaelGrupp/evo/wiki/evo_traj#geometric-alignment

So you could try this:

 evo_traj kitti KeyFrameTrajectory.txt --ref=ground_truth.txt -p --plot_mode=xz --correct_scale --align

[liangsongLee]

Thank you, I tried this, but I got the error : data matrices must have the same shape

[MichaelGrupp]

Can you upload your data here?

[liangsongLee]

OK, here are the datas.
ground_truth.txt
KeyFrameTrajectory.txt

[liangsongLee]

And this is the trajectory file of sequence 09 of KITTI that I got from mono_kitti of ORBSLAM2 , which is in the form of TUM data before I saved it as form of kitti using your code here.
KeyFrameTrajectory_mono.txt

[MichaelGrupp]

The problem is that the kitti format doesn't have timestamps to do timestamp correspondence for alignment, so the only way to do it is that the number of poses must be exactly the same with this format. Formats with timestamps like tum don't have this problem.

But you can probably solve that. The KITTI dataset also has separate files that provide the timestamps.
From a similar issue #125 we wrote a script that can combine this timestamp file and a kitti poses file to a proper trajectory. You can download it here and use it to convert the ground truth to tum format:
https://github.com/MichaelGrupp/evo/blob/master/contrib/kitti_poses_and_timestamps_to_trajectory.py

[liangsongLee]

OK, got it. thank you Michael.