[FieldTrip] CTF275 MEG channel position from FieldTrip to EEGLAB

[Zhi Li]

Hi,

I would like to use ICA and IClabel in EEGLAB to detect artefacts in my MEG
data. But no matter if I used *fieldtrip2eeglab* or *pop_fileio*, the
gradiometer
channel positions cannot be correctly extracted from the ctf275 .ds folder.
The channel positions in eeglab format *EEG* are all empty.

I tried to copy the channel information directly from the header of the
ctf275 data folder but the MEG channels cannot be projected on the 2-D map
appropriately. It seems like the channel position in the MEG data imported
by FieldTrip are the real locations of the MEG helmet and their unit is cm.
whereas the channel position in EEGLAB is based on the 10-10 system which
is already on the scalp. Hence the projected channels on the scalp are all
misplaced if I use the raw XYZ from the header of ctf275 data.

May I ask how I could transform the MEG channel position from FieldTrip to
EEGLAB appropriately, or is there any other solution? Many thanks.

Best regards,

Zhi Li
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.science.ru.nl/pipermail/fieldtrip/attachments/20220630/a4db19fa/attachment.htm>