how to obtain trans.fif file from coregistration between meg and mri with mrilab

Hi,

In the chapter “Head model and forward computation” it says that one can obtain the “trans file” with mrilab if one uses a Neuromag system. But I don’t understand how to obtain the “trans.fif”-file with mrilab.

I coregister the MRI to the digitized points (Nas,LPA,RPA, Coils) from the MEG measurement and save the fiducial coordinates in a .txt file (which can be either stored in “head”, “MRI” or “voxel” coordinates) and the coregistered mri.fif file. But from these two files I don’t know how to create the trans.fif file and I don’t see any option in mrilab to create a trans.fif file. I know that I could use mne.gui.coregistration or men_analyze. But as I’ve already done the coregistration in mrilab I wouldn’t want to do everything again.

It would be great if someone could help me! :slight_smile:

  • MNE-Python version: 0.24.0
  • operating system: MacOS

Thanks,
Alex

If you have a neuromag system you can use the neuromag mrilab program to obtain the transformation, but it is not required. Unless you have a great deal of experience using mrilab, mne.gui.coregistration is likely to produce a more accurate transformation. For instructions, see “Defining the head↔MRI trans using the GUI” at Source alignment and coordinate frames — MNE 0.24.1 documentation .

Hope this helps,

Jon

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