Hi all,
thank you a lot for your answer and sorry for the response delay, I first
wanted to try your suggestion before coming back to you.
@Alex: this is what I want to do: rescale the fsaverage BEM model using the
coreg GUI to fit the standard montage with electrodes constrained on a
sphere. But I do not know how to create the digitized points coordinates
for these electrode.
@Marina: your answer helped me going towards the right direction.
Nevertheless, I could not get it to work correctly.
I created the raw.info['dig'] structure as you suggested but when I use it
in the coregistration GUI, I get far too high fiducials errors:
"LPA: 137548.5mm, NAS: 0.0mm, RPA: 171781.1 mm"
I guess the fiducials positions I read in the standard montage are not in
the correct coordinate system or do not have the correct scaling.
Could you maybe share the code you are using to create the dig structure?
Do you get plausible results for the source reconstruction using this
technique?
Best,
Florian
---------- Message transf?r? ----------
From: "Saiz Al?a, Marina" <marina.saiz-alia15 at imperial.ac.uk>
To: "mne_analysis at nmr.mgh.harvard.edu" <mne_analysis at nmr.mgh.harvard.edu>
Cc:
Date: Fri, 16 Sep 2016 08:23:28 +0000
Subject: [Mne_analysis] 3. Trans file without digitized data (Florian
Aspart)
Hello Florian,I do source reconstruction with EEG 64 channels and using fsaverage
average brain from FreeSurfer too.I had the same problem. I was trying to get the trans file using mne coreg
but my EEG data did not have the dig points. So what I did is to use the
standard 10-20 electrode positions that I read using montage function, when
loading the data.I copied the positions of the EEG channels and the fiducial points into
the raw.info[?dig?] structure, saved the new raw file as .fif and then
when I loaded it in mne correg I would see the digitized points over the
fsaverage brain I previously selected.Let me know if you don?t know how to do it and I will try to help you but
basically you just need to copy the positions into this info structure.
Make sure LPA, RPA and nazion are ordered as dig structure requieres, just
in case. You can load mne sample data set and check how this raw.info[?dig?]
structure has to be.Hope it helps although if you need more help I can send you my code or try
to be more specific. I am not in the office now and I don?t exactly
remember how I did it. But it is basically what I am telling you now.Marina.
---------- Message transf?r? ----------
From: Alexandre Gramfort <alexandre.gramfort at telecom-paristech.fr>
To: Discussion and support forum for the users of MNE Software <
mne_analysis at nmr.mgh.harvard.edu>
Cc:
Date: Mon, 19 Sep 2016 13:32:03 +0200
Subject: Re: [Mne_analysis] Trans file without digitized data
hi Florian,use a standard montage with electrodes constrained on a sphere. If you want
to use a BEM model you need to rescale fsaverage. The coreg GUI in mne
-python
allows you to do this AFAIK.HTH
Alex
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