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

[Arnaud Delorme]

Dear Kirti,

you need to coregister your EGI montage with the head model. This usually involve simple rotation and stretching. You may do that from the EEGLAB graphic interface and then look at the automatically generated command line calls. Note that when you use the graphic interface, EEGLAB should recognize your montage and automatically fill in a basic transformation matrix.

For more information see

http://sccn.ucsd.edu/wiki/Chapter_06:_Data_Averaging#Plotting_ERP_data_as_a_series_of_3-D_maps

Best,

Arno

On 14 Aug 2013, at 16:48, Makoto Miyakoshi wrote:

> Dear Kirti,
> 
> Can you tell us which system generated the .data file?
> 
> Makoto
> 
> 
> 2013/8/13 Kirti Srivastava <kirti.sri1987 at gmail.com>
> can please any one tell me how i can open . DATA file into MATLAB. 
> 
> 
> On Tue, Aug 13, 2013 at 7:02 AM, Makoto Miyakoshi <mmiyakoshi at ucsd.edu> wrote:
> 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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> 
> 
> 
> -- 
> Makoto Miyakoshi
> Swartz Center for Computational Neuroscience
> Institute for Neural Computation, University of California San Diego

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