[Eeglablist] electrode locations shifted when using headplot on EGI's GSN-HydroCel-128.sfp

[Makoto Miyakoshi]

Dear Ingrid and Arno,

If you are using the template channel locations and not the digitized ones,
I don't why you got such a strange plot (actually I don't even know if your
plot is wrong).

The 3D plot head model should have undergone a revision recently. Let me
ask Arno if he knows anything about it.

Makoto


2013/8/7 Ingrid Nieuwenhuis <ingrid.nieuwenhuis at gmail.com>

> Hello everyone,
>
> I am trying to make a beautiful 3D topoplot on the head using headplot. I
> have 128 channel EGI data, GSN-HydroCel-128.sfp layout. When I plot the
> electrode positions they are not correct, see the picture here:
> https://www.dropbox.com/s/g4b1uvwlgof63cm/headplot_GSN-HydroCel-128.jpg.
> It looks as if the net is not pulled down enough: the electrodes that
> should be on the cheeks way under the eyes are located on the eye balls,
> and also the ear in the picture is not in the ear hole of the net. All the
> electrodes are too high up.
>
> I've created the spline file with the option 'sfp' for 'filetype' as I
> read that sfp data format is supported. I used the standard EGI electrode
> location file GSN-HydroCel-128.sfp, after removing the FidNz, FidT9, FidT10
> place holders. Does any one know why this happens, and how I can fix it?
>
> I'm new to EEGlab (normally use FieldTrip). I haven't used the GUI but
> used code:
>
> % step 1 create spline file
> elocs =
> readlocs('C:\Users\Ingrid\Documents\MATLAB\FieldTrip\template\electrode\GSN-HydroCel-128.sfp',
> 'filetype', 'sfp');
> splinefile = [cur_path_MLD, 'EEGLAB_splinefiles', filesep, 'EGI_128.spl'];
> headplot('setup', elocs, splinefile);
>
> % step 2 test the electrode locations
> splinefile = [cur_path_MLD, 'EEGLAB_splinefiles', filesep, 'EGI_128.spl'];
> figure;
> headplot(rand(128,1), splinefile)
>
> Thanks a lot!
> Ingrid
>
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-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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