Motion data units for developing human connectome project

I’m working on an analysis of the third release of dHCP data and I was wondering if anyone knows if the rotation values provided in the motion tsv files are in radians or degrees? I haven’t been able to find a concrete answer in any of the documentation. Thank you so much!

1 Like

Hey! Have you found an answer to that question? I am facing the same issue here :slight_smile: Would like to compute framewise displacement using the MovementRegressors.txt files

Hi! Based on our motion analysis, we think the original data is in radians. Hope this helps!

Ah that probably explains why I get weird framewise-displacement values when using the following formula?:

motion_diff = np.diff(motion, axis=0, prepend=0)
fd = np.sum(np.abs(motion_diff[:, 0:3]) + 50 * np.abs(motion_diff[:, 3:]), axis=1)
mean_fd = np.mean(fd)

Took the formula from this repo

Did you by any chance already calculcate FD and tell me how to do this when the rotational parameters are in radians and not in degrees?

Hm, but in the official wiki it says the parameters are in degrees?

Estimates of motion parameters are saved into two different files: Movement_Regressors.txt and Movement_Regressors_dt.txt. The first file (Movement_Regressors.txt) contains 12 variables. The first six variables are the motion parameters estimates from a rigid-body transformation to the SBRef image acquired at the start of each fMRI scan.

  • trans_x (mm)
  • trans_y (mm)
  • trans_z (mm)
  • rot_x (deg)
  • rot_y (deg)
  • rot_z (deg)