a little confused about the gravity vector

[maoyuyuyuyuyu]

hi I just tried the example dataset to run the Camera IMU calibration。 In the dataset ，the datas showed at the beginning： timestamp, omega_x, omega_y, omega_z, alpha_x, alpha_y, alpha_z 1402065930415759104,-0.0055850536063818549,-0.0027925268031909274,0.017453292519943295,9.733100125,-0.62108783333333339,-0.46581587499999999 1402065930420759040,-0.0013962634015954637,-0.0020943951023931952,0.024434609527920613,9.7249279166666671,-0.67829329166666663,-0.4494714583333333 1402065930425758976,-0.0048869219055841231,-0.00069813170079773186,0.02652900463031381,9.7984777916666665,-0.83356525000000004,-0.44129924999999998 the value of alpha_x is very closed to the value of gravity acceleration. According to this, I first assume that the X-axis represents the direction of the gravity in the coordinate of Imu. The first Question is , for this Kalibr , is that important to fix the X-axis to the direction of Gravity?

And the results report show that: Gravity vector in target coords: [m/s^2] [-0.06523734 8.78297289 -4.36159995] Is the target coordinate represents the world coordinate? And is that means that Y-axis represents the direction of the gravity in the world coordinate of Kalibr?

Thanks !!

[hhmaizi]

I guess it means your chessboard's Y direction is not aligned with gravity. this vector is your chessboard's direction.

[chunibyo-wly]

Hello, do you fix this yet? What should I suppose to get (gravity vector in target coords) when I put an april tag in this orientation

axis Y is up axis X is right axis Z is to person

I think the gravity vector.y is supposed to be around -9.8, am I right?

thanks for your reply.