[FieldTrip] Easycap M10 coregistration with head model – no fiducials

[Herring, J.D. (Jim)]

Dear Milan,

If you have not recorded the electrode positions yourself using, for example, a Polhemus or Localite system you will always end-up with a suboptimal alignment (fiducials, or not).

That being said, you can skip the step of automatic realignment in the tutorial and immediately use ft_electroderealign with cfg.method = 'interactive', to manually rotate, translate, and scale the electrode positions to make it fit as well as possible to your headmodel.

Best,

Jim
________________________________
From: fieldtrip-bounces at science.ru.nl [fieldtrip-bounces at science.ru.nl] on behalf of Milan Mitka [mitka3 at uniba.sk]
Sent: Wednesday, March 18, 2015 9:54 PM
To: fieldtrip at science.ru.nl
Subject: [FieldTrip] Easycap M10 coregistration with head model – no fiducials

Greetings,

I'm having difficulties with aligning easycap M10 electrodes with a head model. I'm following this tutorial: http://fieldtrip.fcdonders.nl/tutorial/headmodel_eeg#align_the_electrodes

The problem as I see it is that the file FieldTrip/template/electrode/easycap-M10.txt that I'm using istead of standard_1020.elc doesn't include fiducials and can therefore not be properly aligned with the head model automatically.

How can I properly align M10 electrodes defined in spherical coordinates or convert MNI cartesian coordinates to the head model coordinates which appear to use CTF, please?

Yours faithfully
Milan Mitka
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